lguest.c
/*P:100
* This is the Launcher code, a simple program which lays out the "physical"
* memory for the new Guest by mapping the kernel image and the virtual
* devices, then opens /dev/lguest to tell the kernel about the Guest and
* control it.
:*/
#define _LARGEFILE64_SOURCE
#define _GNU_SOURCE
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <err.h>
#include <stdint.h>
#include <stdlib.h>
#include <elf.h>
#include <sys/mman.h>
#include <sys/param.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <sys/eventfd.h>
#include <fcntl.h>
#include <stdbool.h>
#include <errno.h>
#include <ctype.h>
#include <sys/socket.h>
#include <sys/ioctl.h>
#include <sys/time.h>
#include <time.h>
#include <netinet/in.h>
#include <net/if.h>
#include <linux/sockios.h>
#include <linux/if_tun.h>
#include <sys/uio.h>
#include <termios.h>
#include <getopt.h>
#include <assert.h>
#include <sched.h>
#include <limits.h>
#include <stddef.h>
#include <signal.h>
#include <pwd.h>
#include <grp.h>
#include <sys/user.h>
#include <linux/pci_regs.h>
#ifndef VIRTIO_F_ANY_LAYOUT
#define VIRTIO_F_ANY_LAYOUT 27
#endif
/*L:110
* We can ignore the 43 include files we need for this program, but I do want
* to draw attention to the use of kernel-style types.
*
* As Linus said, "C is a Spartan language, and so should your naming be." I
* like these abbreviations, so we define them here. Note that u64 is always
* unsigned long long, which works on all Linux systems: this means that we can
* use %llu in printf for any u64.
*/
typedef unsigned long long u64;
typedef uint32_t u32;
typedef uint16_t u16;
typedef uint8_t u8;
/*:*/
#define VIRTIO_CONFIG_NO_LEGACY
#define VIRTIO_PCI_NO_LEGACY
#define VIRTIO_BLK_NO_LEGACY
#define VIRTIO_NET_NO_LEGACY
/* Use in-kernel ones, which defines VIRTIO_F_VERSION_1 */
#include "../../include/uapi/linux/virtio_config.h"
#include "../../include/uapi/linux/virtio_net.h"
#include "../../include/uapi/linux/virtio_blk.h"
#include "../../include/uapi/linux/virtio_console.h"
#include "../../include/uapi/linux/virtio_rng.h"
#include <linux/virtio_ring.h>
#include "../../include/uapi/linux/virtio_pci.h"
#include <asm/bootparam.h>
#include "../../include/linux/lguest_launcher.h"
#define BRIDGE_PFX "bridge:"
#ifndef SIOCBRADDIF
#define SIOCBRADDIF 0x89a2 /* add interface to bridge */
#endif
/* We can have up to 256 pages for devices. */
#define DEVICE_PAGES 256
/* This will occupy 3 pages: it must be a power of 2. */
#define VIRTQUEUE_NUM 256
/*L:120
* verbose is both a global flag and a macro. The C preprocessor allows
* this, and although I wouldn't recommend it, it works quite nicely here.
*/
static bool verbose;
#define verbose(args...) \
do { if (verbose) printf(args); } while(0)
/*:*/
/* The pointer to the start of guest memory. */
static void *guest_base;
/* The maximum guest physical address allowed, and maximum possible. */
static unsigned long guest_limit, guest_max, guest_mmio;
/* The /dev/lguest file descriptor. */
static int lguest_fd;
/* a per-cpu variable indicating whose vcpu is currently running */
static unsigned int __thread cpu_id;
/* 5 bit device number in the PCI_CONFIG_ADDR => 32 only */
#define MAX_PCI_DEVICES 32
/* This is our list of devices. */
struct device_list {
/* Counter to assign interrupt numbers. */
unsigned int next_irq;
/* Counter to print out convenient device numbers. */
unsigned int device_num;
/* PCI devices. */
struct device *pci[MAX_PCI_DEVICES];
};
/* The list of Guest devices, based on command line arguments. */
static struct device_list devices;
/*
* Just like struct virtio_pci_cfg_cap in uapi/linux/virtio_pci.h,
* but uses a u32 explicitly for the data.
*/
struct virtio_pci_cfg_cap_u32 {
struct virtio_pci_cap cap;
u32 pci_cfg_data; /* Data for BAR access. */
};
struct virtio_pci_mmio {
struct virtio_pci_common_cfg cfg;
u16 notify;
u8 isr;
u8 padding;
/* Device-specific configuration follows this. */
};
/* This is the layout (little-endian) of the PCI config space. */
struct pci_config {
u16 vendor_id, device_id;
u16 command, status;
u8 revid, prog_if, subclass, class;
u8 cacheline_size, lat_timer, header_type, bist;
u32 bar[6];
u32 cardbus_cis_ptr;
u16 subsystem_vendor_id, subsystem_device_id;
u32 expansion_rom_addr;
u8 capabilities, reserved1[3];
u32 reserved2;
u8 irq_line, irq_pin, min_grant, max_latency;
/* Now, this is the linked capability list. */
struct virtio_pci_cap common;
struct virtio_pci_notify_cap notify;
struct virtio_pci_cap isr;
struct virtio_pci_cap device;
struct virtio_pci_cfg_cap_u32 cfg_access;
};
/* The device structure describes a single device. */
struct device {
/* The name of this device, for --verbose. */
const char *name;
/* Any queues attached to this device */
struct virtqueue *vq;
/* Is it operational */
bool running;
/* Has it written FEATURES_OK but not re-checked it? */
bool wrote_features_ok;
/* PCI configuration */
union {
struct pci_config config;
u32 config_words[sizeof(struct pci_config) / sizeof(u32)];
};
/* Features we offer, and those accepted. */
u64 features, features_accepted;
/* Device-specific config hangs off the end of this. */
struct virtio_pci_mmio *mmio;
/* PCI MMIO resources (all in BAR0) */
size_t mmio_size;
u32 mmio_addr;
/* Device-specific data. */
void *priv;
};
/* The virtqueue structure describes a queue attached to a device. */
struct virtqueue {
struct virtqueue *next;
/* Which device owns me. */
struct device *dev;
/* Name for printing errors. */
const char *name;
/* The actual ring of buffers. */
struct vring vring;
/* The information about this virtqueue (we only use queue_size on) */
struct virtio_pci_common_cfg pci_config;
/* Last available index we saw. */
u16 last_avail_idx;
/* How many are used since we sent last irq? */
unsigned int pending_used;
/* Eventfd where Guest notifications arrive. */
int eventfd;
/* Function for the thread which is servicing this virtqueue. */
void (*service)(struct virtqueue *vq);
pid_t thread;
};
/* Remember the arguments to the program so we can "reboot" */
static char **main_args;
/* The original tty settings to restore on exit. */
static struct termios orig_term;
/*
* We have to be careful with barriers: our devices are all run in separate
* threads and so we need to make sure that changes visible to the Guest happen
* in precise order.
*/
#define wmb() __asm__ __volatile__("" : : : "memory")
#define rmb() __asm__ __volatile__("lock; addl $0,0(%%esp)" : : : "memory")
#define mb() __asm__ __volatile__("lock; addl $0,0(%%esp)" : : : "memory")
/* Wrapper for the last available index. Makes it easier to change. */
#define lg_last_avail(vq) ((vq)->last_avail_idx)
/*
* The virtio configuration space is defined to be little-endian. x86 is
* little-endian too, but it's nice to be explicit so we have these helpers.
*/
#define cpu_to_le16(v16) (v16)
#define cpu_to_le32(v32) (v32)
#define cpu_to_le64(v64) (v64)
#define le16_to_cpu(v16) (v16)
#define le32_to_cpu(v32) (v32)
#define le64_to_cpu(v64) (v64)
/*
* A real device would ignore weird/non-compliant driver behaviour. We
* stop and flag it, to help debugging Linux problems.
*/
#define bad_driver(d, fmt, ...) \
errx(1, "%s: bad driver: " fmt, (d)->name, ## __VA_ARGS__)
#define bad_driver_vq(vq, fmt, ...) \
errx(1, "%s vq %s: bad driver: " fmt, (vq)->dev->name, \
vq->name, ## __VA_ARGS__)
/* Is this iovec empty? */
static bool iov_empty(const struct iovec iov[], unsigned int num_iov)
{
unsigned int i;
for (i = 0; i < num_iov; i++)
if (iov[i].iov_len)
return false;
return true;
}
/* Take len bytes from the front of this iovec. */
static void iov_consume(struct device *d,
struct iovec iov[], unsigned num_iov,
void *dest, unsigned len)
{
unsigned int i;
for (i = 0; i < num_iov; i++) {
unsigned int used;
used = iov[i].iov_len < len ? iov[i].iov_len : len;
if (dest) {
memcpy(dest, iov[i].iov_base, used);
dest += used;
}
iov[i].iov_base += used;
iov[i].iov_len -= used;
len -= used;
}
if (len != 0)
bad_driver(d, "iovec too short!");
}
/*L:100
* The Launcher code itself takes us out into userspace, that scary place where
* pointers run wild and free! Unfortunately, like most userspace programs,
* it's quite boring (which is why everyone likes to hack on the kernel!).
* Perhaps if you make up an Lguest Drinking Game at this point, it will get
* you through this section. Or, maybe not.
*
* The Launcher sets up a big chunk of memory to be the Guest's "physical"
* memory and stores it in "guest_base". In other words, Guest physical ==
* Launcher virtual with an offset.
*
* This can be tough to get your head around, but usually it just means that we
* use these trivial conversion functions when the Guest gives us its
* "physical" addresses:
*/
static void *from_guest_phys(unsigned long addr)
{
return guest_base + addr;
}
static unsigned long to_guest_phys(const void *addr)
{
return (addr - guest_base);
}
/*L:130
* Loading the Kernel.
*
* We start with couple of simple helper routines. open_or_die() avoids
* error-checking code cluttering the callers:
*/
static int open_or_die(const char *name, int flags)
{
int fd = open(name, flags);
if (fd < 0)
err(1, "Failed to open %s", name);
return fd;
}
/* map_zeroed_pages() takes a number of pages. */
static void *map_zeroed_pages(unsigned int num)
{
int fd = open_or_die("/dev/zero", O_RDONLY);
void *addr;
/*
* We use a private mapping (ie. if we write to the page, it will be
* copied). We allocate an extra two pages PROT_NONE to act as guard
* pages against read/write attempts that exceed allocated space.
*/
addr = mmap(NULL, getpagesize() * (num+2),
PROT_NONE, MAP_PRIVATE, fd, 0);
if (addr == MAP_FAILED)
err(1, "Mmapping %u pages of /dev/zero", num);
if (mprotect(addr + getpagesize(), getpagesize() * num,
PROT_READ|PROT_WRITE) == -1)
err(1, "mprotect rw %u pages failed", num);
/*
* One neat mmap feature is that you can close the fd, and it
* stays mapped.
*/
close(fd);
/* Return address after PROT_NONE page */
return addr + getpagesize();
}
/* Get some bytes which won't be mapped into the guest. */
static unsigned long get_mmio_region(size_t size)
{
unsigned long addr = guest_mmio;
size_t i;
if (!size)
return addr;
/* Size has to be a power of 2 (and multiple of 16) */
for (i = 1; i < size; i <<= 1);
guest_mmio += i;
return addr;
}
/*
* This routine is used to load the kernel or initrd. It tries mmap, but if
* that fails (Plan 9's kernel file isn't nicely aligned on page boundaries),
* it falls back to reading the memory in.
*/
static void map_at(int fd, void *addr, unsigned long offset, unsigned long len)
{
ssize_t r;
/*
* We map writable even though for some segments are marked read-only.
* The kernel really wants to be writable: it patches its own
* instructions.
*
* MAP_PRIVATE means that the page won't be copied until a write is
* done to it. This allows us to share untouched memory between
* Guests.
*/
if (mmap(addr, len, PROT_READ|PROT_WRITE,
MAP_FIXED|MAP_PRIVATE, fd, offset) != MAP_FAILED)
return;
/* pread does a seek and a read in one shot: saves a few lines. */
r = pread(fd, addr, len, offset);
if (r != len)
err(1, "Reading offset %lu len %lu gave %zi", offset, len, r);
}
/*
* This routine takes an open vmlinux image, which is in ELF, and maps it into
* the Guest memory. ELF = Embedded Linking Format, which is the format used
* by all modern binaries on Linux including the kernel.
*
* The ELF headers give *two* addresses: a physical address, and a virtual
* address. We use the physical address; the Guest will map itself to the
* virtual address.
*
* We return the starting address.
*/
static unsigned long map_elf(int elf_fd, const Elf32_Ehdr *ehdr)
{
Elf32_Phdr phdr[ehdr->e_phnum];
unsigned int i;
/*
* Sanity checks on the main ELF header: an x86 executable with a
* reasonable number of correctly-sized program headers.
*/
if (ehdr->e_type != ET_EXEC
|| ehdr->e_machine != EM_386
|| ehdr->e_phentsize != sizeof(Elf32_Phdr)
|| ehdr->e_phnum < 1 || ehdr->e_phnum > 65536U/sizeof(Elf32_Phdr))
errx(1, "Malformed elf header");
/*
* An ELF executable contains an ELF header and a number of "program"
* headers which indicate which parts ("segments") of the program to
* load where.
*/
/* We read in all the program headers at once: */
if (lseek(elf_fd, ehdr->e_phoff, SEEK_SET) < 0)
err(1, "Seeking to program headers");
if (read(elf_fd, phdr, sizeof(phdr)) != sizeof(phdr))
err(1, "Reading program headers");
/*
* Try all the headers: there are usually only three. A read-only one,
* a read-write one, and a "note" section which we don't load.
*/
for (i = 0; i < ehdr->e_phnum; i++) {
/* If this isn't a loadable segment, we ignore it */
if (phdr[i].p_type != PT_LOAD)
continue;
verbose("Section %i: size %i addr %p\n",
i, phdr[i].p_memsz, (void *)phdr[i].p_paddr);
/* We map this section of the file at its physical address. */
map_at(elf_fd, from_guest_phys(phdr[i].p_paddr),
phdr[i].p_offset, phdr[i].p_filesz);
}
/* The entry point is given in the ELF header. */
return ehdr->e_entry;
}
/*L:150
* A bzImage, unlike an ELF file, is not meant to be loaded. You're supposed
* to jump into it and it will unpack itself. We used to have to perform some
* hairy magic because the unpacking code scared me.
*
* Fortunately, Jeremy Fitzhardinge convinced me it wasn't that hard and wrote
* a small patch to jump over the tricky bits in the Guest, so now we just read
* the funky header so we know where in the file to load, and away we go!
*/
static unsigned long load_bzimage(int fd)
{
struct boot_params boot;
int r;
/* Modern bzImages get loaded at 1M. */
void *p = from_guest_phys(0x100000);
/*
* Go back to the start of the file and read the header. It should be
* a Linux boot header (see Documentation/x86/boot.txt)
*/
lseek(fd, 0, SEEK_SET);
read(fd, &boot, sizeof(boot));
/* Inside the setup_hdr, we expect the magic "HdrS" */
if (memcmp(&boot.hdr.header, "HdrS", 4) != 0)
errx(1, "This doesn't look like a bzImage to me");
/* Skip over the extra sectors of the header. */
lseek(fd, (boot.hdr.setup_sects+1) * 512, SEEK_SET);
/* Now read everything into memory. in nice big chunks. */
while ((r = read(fd, p, 65536)) > 0)
p += r;
/* Finally, code32_start tells us where to enter the kernel. */
return boot.hdr.code32_start;
}
/*L:140
* Loading the kernel is easy when it's a "vmlinux", but most kernels
* come wrapped up in the self-decompressing "bzImage" format. With a little
* work, we can load those, too.
*/
static unsigned long load_kernel(int fd)
{
Elf32_Ehdr hdr;
/* Read in the first few bytes. */
if (read(fd, &hdr, sizeof(hdr)) != sizeof(hdr))
err(1, "Reading kernel");
/* If it's an ELF file, it starts with "\177ELF" */
if (memcmp(hdr.e_ident, ELFMAG, SELFMAG) == 0)
return map_elf(fd, &hdr);
/* Otherwise we assume it's a bzImage, and try to load it. */
return load_bzimage(fd);
}
/*
* This is a trivial little helper to align pages. Andi Kleen hated it because
* it calls getpagesize() twice: "it's dumb code."
*
* Kernel guys get really het up about optimization, even when it's not
* necessary. I leave this code as a reaction against that.
*/
static inline unsigned long page_align(unsigned long addr)
{
/* Add upwards and truncate downwards. */
return ((addr + getpagesize()-1) & ~(getpagesize()-1));
}
/*L:180
* An "initial ram disk" is a disk image loaded into memory along with the
* kernel which the kernel can use to boot from without needing any drivers.
* Most distributions now use this as standard: the initrd contains the code to
* load the appropriate driver modules for the current machine.
*
* Importantly, James Morris works for RedHat, and Fedora uses initrds for its
* kernels. He sent me this (and tells me when I break it).
*/
static unsigned long load_initrd(const char *name, unsigned long mem)
{
int ifd;
struct stat st;
unsigned long len;
ifd = open_or_die(name, O_RDONLY);
/* fstat() is needed to get the file size. */
if (fstat(ifd, &st) < 0)
err(1, "fstat() on initrd '%s'", name);
/*
* We map the initrd at the top of memory, but mmap wants it to be
* page-aligned, so we round the size up for that.
*/
len = page_align(st.st_size);
map_at(ifd, from_guest_phys(mem - len), 0, st.st_size);
/*
* Once a file is mapped, you can close the file descriptor. It's a
* little odd, but quite useful.
*/
close(ifd);
verbose("mapped initrd %s size=%lu @ %p\n", name, len, (void*)mem-len);
/* We return the initrd size. */
return len;
}
/*:*/
/*
* Simple routine to roll all the commandline arguments together with spaces
* between them.
*/
static void concat(char *dst, char *args[])
{
unsigned int i, len = 0;
for (i = 0; args[i]; i++) {
if (i) {
strcat(dst+len, " ");
len++;
}
strcpy(dst+len, args[i]);
len += strlen(args[i]);
}
/* In case it's empty. */
dst[len] = '\0';
}
/*L:185
* This is where we actually tell the kernel to initialize the Guest. We
* saw the arguments it expects when we looked at initialize() in lguest_user.c:
* the base of Guest "physical" memory, the top physical page to allow and the
* entry point for the Guest.
*/
static void tell_kernel(unsigned long start)
{
unsigned long args[] = { LHREQ_INITIALIZE,
(unsigned long)guest_base,
guest_limit / getpagesize(), start,
(guest_mmio+getpagesize()-1) / getpagesize() };
verbose("Guest: %p - %p (%#lx, MMIO %#lx)\n",
guest_base, guest_base + guest_limit,
guest_limit, guest_mmio);
lguest_fd = open_or_die("/dev/lguest", O_RDWR);
if (write(lguest_fd, args, sizeof(args)) < 0)
err(1, "Writing to /dev/lguest");
}
/*:*/
/*L:200
* Device Handling.
*
* When the Guest gives us a buffer, it sends an array of addresses and sizes.
* We need to make sure it's not trying to reach into the Launcher itself, so
* we have a convenient routine which checks it and exits with an error message
* if something funny is going on:
*/
static void *_check_pointer(struct device *d,
unsigned long addr, unsigned int size,
unsigned int line)
{
/*
* Check if the requested address and size exceeds the allocated memory,
* or addr + size wraps around.
*/
if ((addr + size) > guest_limit || (addr + size) < addr)
bad_driver(d, "%s:%i: Invalid address %#lx",
__FILE__, line, addr);
/*
* We return a pointer for the caller's convenience, now we know it's
* safe to use.
*/
return from_guest_phys(addr);
}
/* A macro which transparently hands the line number to the real function. */
#define check_pointer(d,addr,size) _check_pointer(d, addr, size, __LINE__)
/*
* Each buffer in the virtqueues is actually a chain of descriptors. This
* function returns the next descriptor in the chain, or vq->vring.num if we're
* at the end.
*/
static unsigned next_desc(struct device *d, struct vring_desc *desc,
unsigned int i, unsigned int max)
{
unsigned int next;
/* If this descriptor says it doesn't chain, we're done. */
if (!(desc[i].flags & VRING_DESC_F_NEXT))
return max;
/* Check they're not leading us off end of descriptors. */
next = desc[i].next;
/* Make sure compiler knows to grab that: we don't want it changing! */
wmb();
if (next >= max)
bad_driver(d, "Desc next is %u", next);
return next;
}
/*
* This actually sends the interrupt for this virtqueue, if we've used a
* buffer.
*/
static void trigger_irq(struct virtqueue *vq)
{
unsigned long buf[] = { LHREQ_IRQ, vq->dev->config.irq_line };
/* Don't inform them if nothing used. */
if (!vq->pending_used)
return;
vq->pending_used = 0;
/*
* 2.4.7.1:
*
* If the VIRTIO_F_EVENT_IDX feature bit is not negotiated:
* The driver MUST set flags to 0 or 1.
*/
if (vq->vring.avail->flags > 1)
bad_driver_vq(vq, "avail->flags = %u\n", vq->vring.avail->flags);
/*
* 2.4.7.2:
*
* If the VIRTIO_F_EVENT_IDX feature bit is not negotiated:
*
* - The device MUST ignore the used_event value.
* - After the device writes a descriptor index into the used ring:
* - If flags is 1, the device SHOULD NOT send an interrupt.
* - If flags is 0, the device MUST send an interrupt.
*/
if (vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT) {
return;
}
/*
* 4.1.4.5.1:
*
* If MSI-X capability is disabled, the device MUST set the Queue
* Interrupt bit in ISR status before sending a virtqueue notification
* to the driver.
*/
vq->dev->mmio->isr = 0x1;
/* Send the Guest an interrupt tell them we used something up. */
if (write(lguest_fd, buf, sizeof(buf)) != 0)
err(1, "Triggering irq %i", vq->dev->config.irq_line);
}
/*
* This looks in the virtqueue for the first available buffer, and converts
* it to an iovec for convenient access. Since descriptors consist of some
* number of output then some number of input descriptors, it's actually two
* iovecs, but we pack them into one and note how many of each there were.
*
* This function waits if necessary, and returns the descriptor number found.
*/
static unsigned wait_for_vq_desc(struct virtqueue *vq,
struct iovec iov[],
unsigned int *out_num, unsigned int *in_num)
{
unsigned int i, head, max;
struct vring_desc *desc;
u16 last_avail = lg_last_avail(vq);
/*
* 2.4.7.1:
*
* The driver MUST handle spurious interrupts from the device.
*
* That's why this is a while loop.
*/
/* There's nothing available? */
while (last_avail == vq->vring.avail->idx) {
u64 event;
/*
* Since we're about to sleep, now is a good time to tell the
* Guest about what we've used up to now.
*/
trigger_irq(vq);
/* OK, now we need to know about added descriptors. */
vq->vring.used->flags &= ~VRING_USED_F_NO_NOTIFY;
/*
* They could have slipped one in as we were doing that: make
* sure it's written, then check again.
*/
mb();
if (last_avail != vq->vring.avail->idx) {
vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY;
break;
}
/* Nothing new? Wait for eventfd to tell us they refilled. */
if (read(vq->eventfd, &event, sizeof(event)) != sizeof(event))
errx(1, "Event read failed?");
/* We don't need to be notified again. */
vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY;
}
/* Check it isn't doing very strange things with descriptor numbers. */
if ((u16)(vq->vring.avail->idx - last_avail) > vq->vring.num)
bad_driver_vq(vq, "Guest moved used index from %u to %u",
last_avail, vq->vring.avail->idx);
/*
* Make sure we read the descriptor number *after* we read the ring
* update; don't let the cpu or compiler change the order.
*/
rmb();
/*
* Grab the next descriptor number they're advertising, and increment
* the index we've seen.
*/
head = vq->vring.avail->ring[last_avail % vq->vring.num];
lg_last_avail(vq)++;
/* If their number is silly, that's a fatal mistake. */
if (head >= vq->vring.num)
bad_driver_vq(vq, "Guest says index %u is available", head);
/* When we start there are none of either input nor output. */
*out_num = *in_num = 0;
max = vq->vring.num;
desc = vq->vring.desc;
i = head;
/*
* We have to read the descriptor after we read the descriptor number,
* but there's a data dependency there so the CPU shouldn't reorder
* that: no rmb() required.
*/
do {
/*
* If this is an indirect entry, then this buffer contains a
* descriptor table which we handle as if it's any normal
* descriptor chain.
*/
if (desc[i].flags & VRING_DESC_F_INDIRECT) {
/* 2.4.5.3.1:
*
* The driver MUST NOT set the VIRTQ_DESC_F_INDIRECT
* flag unless the VIRTIO_F_INDIRECT_DESC feature was
* negotiated.
*/
if (!(vq->dev->features_accepted &
(1<<VIRTIO_RING_F_INDIRECT_DESC)))
bad_driver_vq(vq, "vq indirect not negotiated");
/*
* 2.4.5.3.1:
*
* The driver MUST NOT set the VIRTQ_DESC_F_INDIRECT
* flag within an indirect descriptor (ie. only one
* table per descriptor).
*/
if (desc != vq->vring.desc)
bad_driver_vq(vq, "Indirect within indirect");
/*
* Proposed update VIRTIO-134 spells this out:
*
* A driver MUST NOT set both VIRTQ_DESC_F_INDIRECT
* and VIRTQ_DESC_F_NEXT in flags.
*/
if (desc[i].flags & VRING_DESC_F_NEXT)
bad_driver_vq(vq, "indirect and next together");
if (desc[i].len % sizeof(struct vring_desc))
bad_driver_vq(vq,
"Invalid size for indirect table");
/*
* 2.4.5.3.2:
*
* The device MUST ignore the write-only flag
* (flags&VIRTQ_DESC_F_WRITE) in the descriptor that
* refers to an indirect table.
*
* We ignore it here: :)
*/
max = desc[i].len / sizeof(struct vring_desc);
desc = check_pointer(vq->dev, desc[i].addr, desc[i].len);
i = 0;
/* 2.4.5.3.1:
*
* A driver MUST NOT create a descriptor chain longer
* than the Queue Size of the device.
*/
if (max > vq->pci_config.queue_size)
bad_driver_vq(vq,
"indirect has too many entries");
}
/* Grab the first descriptor, and check it's OK. */
iov[*out_num + *in_num].iov_len = desc[i].len;
iov[*out_num + *in_num].iov_base
= check_pointer(vq->dev, desc[i].addr, desc[i].len);
/* If this is an input descriptor, increment that count. */
if (desc[i].flags & VRING_DESC_F_WRITE)
(*in_num)++;
else {
/*
* If it's an output descriptor, they're all supposed
* to come before any input descriptors.
*/
if (*in_num)
bad_driver_vq(vq,
"Descriptor has out after in");
(*out_num)++;
}
/* If we've got too many, that implies a descriptor loop. */
if (*out_num + *in_num > max)
bad_driver_vq(vq, "Looped descriptor");
} while ((i = next_desc(vq->dev, desc, i, max)) != max);
return head;
}
/*
* After we've used one of their buffers, we tell the Guest about it. Sometime
* later we'll want to send them an interrupt using trigger_irq(); note that
* wait_for_vq_desc() does that for us if it has to wait.
*/
static void add_used(struct virtqueue *vq, unsigned int head, int len)
{
struct vring_used_elem *used;
/*
* The virtqueue contains a ring of used buffers. Get a pointer to the
* next entry in that used ring.
*/
used = &vq->vring.used->ring[vq->vring.used->idx % vq->vring.num];
used->id = head;
used->len = len;
/* Make sure buffer is written before we update index. */
wmb();
vq->vring.used->idx++;
vq->pending_used++;
}
/* And here's the combo meal deal. Supersize me! */
static void add_used_and_trigger(struct virtqueue *vq, unsigned head, int len)
{
add_used(vq, head, len);
trigger_irq(vq);
}
/*
* The Console
*
* We associate some data with the console for our exit hack.
*/
struct console_abort {
/* How many times have they hit ^C? */
int count;
/* When did they start? */
struct timeval start;
};
/* This is the routine which handles console input (ie. stdin). */
static void console_input(struct virtqueue *vq)
{
int len;
unsigned int head, in_num, out_num;
struct console_abort *abort = vq->dev->priv;
struct iovec iov[vq->vring.num];
/* Make sure there's a descriptor available. */
head = wait_for_vq_desc(vq, iov, &out_num, &in_num);
if (out_num)
bad_driver_vq(vq, "Output buffers in console in queue?");
/* Read into it. This is where we usually wait. */
len = readv(STDIN_FILENO, iov, in_num);
if (len <= 0) {
/* Ran out of input? */
warnx("Failed to get console input, ignoring console.");
/*
* For simplicity, dying threads kill the whole Launcher. So
* just nap here.
*/
for (;;)
pause();
}
/* Tell the Guest we used a buffer. */
add_used_and_trigger(vq, head, len);
/*
* Three ^C within one second? Exit.
*
* This is such a hack, but works surprisingly well. Each ^C has to
* be in a buffer by itself, so they can't be too fast. But we check
* that we get three within about a second, so they can't be too
* slow.
*/
if (len != 1 || ((char *)iov[0].iov_base)[0] != 3) {
abort->count = 0;
return;
}
abort->count++;
if (abort->count == 1)
gettimeofday(&abort->start, NULL);
else if (abort->count == 3) {
struct timeval now;
gettimeofday(&now, NULL);
/* Kill all Launcher processes with SIGINT, like normal ^C */
if (now.tv_sec <= abort->start.tv_sec+1)
kill(0, SIGINT);
abort->count = 0;
}
}
/* This is the routine which handles console output (ie. stdout). */
static void console_output(struct virtqueue *vq)
{
unsigned int head, out, in;
struct iovec iov[vq->vring.num];
/* We usually wait in here, for the Guest to give us something. */
head = wait_for_vq_desc(vq, iov, &out, &in);
if (in)
bad_driver_vq(vq, "Input buffers in console output queue?");
/* writev can return a partial write, so we loop here. */
while (!iov_empty(iov, out)) {
int len = writev(STDOUT_FILENO, iov, out);
if (len <= 0) {
warn("Write to stdout gave %i (%d)", len, errno);
break;
}
iov_consume(vq->dev, iov, out, NULL, len);
}
/*
* We're finished with that buffer: if we're going to sleep,
* wait_for_vq_desc() will prod the Guest with an interrupt.
*/
add_used(vq, head, 0);
}
/*
* The Network
*
* Handling output for network is also simple: we get all the output buffers
* and write them to /dev/net/tun.
*/
struct net_info {
int tunfd;
};
static void net_output(struct virtqueue *vq)
{
struct net_info *net_info = vq->dev->priv;
unsigned int head, out, in;
struct iovec iov[vq->vring.num];
/* We usually wait in here for the Guest to give us a packet. */
head = wait_for_vq_desc(vq, iov, &out, &in);
if (in)
bad_driver_vq(vq, "Input buffers in net output queue?");
/*
* Send the whole thing through to /dev/net/tun. It expects the exact
* same format: what a coincidence!
*/
if (writev(net_info->tunfd, iov, out) < 0)
warnx("Write to tun failed (%d)?", errno);
/*
* Done with that one; wait_for_vq_desc() will send the interrupt if
* all packets are processed.
*/
add_used(vq, head, 0);
}
/*
* Handling network input is a bit trickier, because I've tried to optimize it.
*
* First we have a helper routine which tells is if from this file descriptor
* (ie. the /dev/net/tun device) will block:
*/
static bool will_block(int fd)
{
fd_set fdset;
struct timeval zero = { 0, 0 };
FD_ZERO(&fdset);
FD_SET(fd, &fdset);
return select(fd+1, &fdset, NULL, NULL, &zero) != 1;
}
/*
* This handles packets coming in from the tun device to our Guest. Like all
* service routines, it gets called again as soon as it returns, so you don't
* see a while(1) loop here.
*/
static void net_input(struct virtqueue *vq)
{
int len;
unsigned int head, out, in;
struct iovec iov[vq->vring.num];
struct net_info *net_info = vq->dev->priv;
/*
* Get a descriptor to write an incoming packet into. This will also
* send an interrupt if they're out of descriptors.
*/
head = wait_for_vq_desc(vq, iov, &out, &in);
if (out)
bad_driver_vq(vq, "Output buffers in net input queue?");
/*
* If it looks like we'll block reading from the tun device, send them
* an interrupt.
*/
if (vq->pending_used && will_block(net_info->tunfd))
trigger_irq(vq);
/*
* Read in the packet. This is where we normally wait (when there's no
* incoming network traffic).
*/
len = readv(net_info->tunfd, iov, in);
if (len <= 0)
warn("Failed to read from tun (%d).", errno);
/*
* Mark that packet buffer as used, but don't interrupt here. We want
* to wait until we've done as much work as we can.
*/
add_used(vq, head, len);
}
/*:*/
/* This is the helper to create threads: run the service routine in a loop. */
static int do_thread(void *_vq)
{
struct virtqueue *vq = _vq;
for (;;)
vq->service(vq);
return 0;
}
/*
* When a child dies, we kill our entire process group with SIGTERM. This
* also has the side effect that the shell restores the console for us!
*/
static void kill_launcher(int signal)
{
kill(0, SIGTERM);
}
static void reset_vq_pci_config(struct virtqueue *vq)
{
vq->pci_config.queue_size = VIRTQUEUE_NUM;
vq->pci_config.queue_enable = 0;
}
static void reset_device(struct device *dev)
{
struct virtqueue *vq;
verbose("Resetting device %s\n", dev->name);
/* Clear any features they've acked. */
dev->features_accepted = 0;
/* We're going to be explicitly killing threads, so ignore them. */
signal(SIGCHLD, SIG_IGN);
/*
* 4.1.4.3.1:
*
* The device MUST present a 0 in queue_enable on reset.
*
* This means we set it here, and reset the saved ones in every vq.
*/
dev->mmio->cfg.queue_enable = 0;
/* Get rid of the virtqueue threads */
for (vq = dev->vq; vq; vq = vq->next) {
vq->last_avail_idx = 0;
reset_vq_pci_config(vq);
if (vq->thread != (pid_t)-1) {
kill(vq->thread, SIGTERM);
waitpid(vq->thread, NULL, 0);
vq->thread = (pid_t)-1;
}
}
dev->running = false;
dev->wrote_features_ok = false;
/* Now we care if threads die. */
signal(SIGCHLD, (void *)kill_launcher);
}
static void cleanup_devices(void)
{
unsigned int i;
for (i = 1; i < MAX_PCI_DEVICES; i++) {
struct device *d = devices.pci[i];
if (!d)
continue;
reset_device(d);
}
/* If we saved off the original terminal settings, restore them now. */
if (orig_term.c_lflag & (ISIG|ICANON|ECHO))
tcsetattr(STDIN_FILENO, TCSANOW, &orig_term);
}
/*L:217
* We do PCI. This is mainly done to let us test the kernel virtio PCI
* code.
*/
/* Linux expects a PCI host bridge: ours is a dummy, and first on the bus. */
static struct device pci_host_bridge;
static void init_pci_host_bridge(void)
{
pci_host_bridge.name = "PCI Host Bridge";
pci_host_bridge.config.class = 0x06; /* bridge */
pci_host_bridge.config.subclass = 0; /* host bridge */
devices.pci[0] = &pci_host_bridge;
}
/* The IO ports used to read the PCI config space. */
#define PCI_CONFIG_ADDR 0xCF8
#define PCI_CONFIG_DATA 0xCFC
/*
* Not really portable, but does help readability: this is what the Guest
* writes to the PCI_CONFIG_ADDR IO port.
*/
union pci_config_addr {
struct {
unsigned mbz: 2;
unsigned offset: 6;
unsigned funcnum: 3;
unsigned devnum: 5;
unsigned busnum: 8;
unsigned reserved: 7;
unsigned enabled : 1;
} bits;
u32 val;
};
/*
* We cache what they wrote to the address port, so we know what they're
* talking about when they access the data port.
*/
static union pci_config_addr pci_config_addr;
static struct device *find_pci_device(unsigned int index)
{
return devices.pci[index];
}
/* PCI can do 1, 2 and 4 byte reads; we handle that here. */
static void ioread(u16 off, u32 v, u32 mask, u32 *val)
{
assert(off < 4);
assert(mask == 0xFF || mask == 0xFFFF || mask == 0xFFFFFFFF);
*val = (v >> (off * 8)) & mask;
}
/* PCI can do 1, 2 and 4 byte writes; we handle that here. */
static void iowrite(u16 off, u32 v, u32 mask, u32 *dst)
{
assert(off < 4);
assert(mask == 0xFF || mask == 0xFFFF || mask == 0xFFFFFFFF);
*dst &= ~(mask << (off * 8));
*dst |= (v & mask) << (off * 8);
}
/*
* Where PCI_CONFIG_DATA accesses depends on the previous write to
* PCI_CONFIG_ADDR.
*/
static struct device *dev_and_reg(u32 *reg)
{
if (!pci_config_addr.bits.enabled)
return NULL;
if (pci_config_addr.bits.funcnum != 0)
return NULL;
if (pci_config_addr.bits.busnum != 0)
return NULL;
if (pci_config_addr.bits.offset * 4 >= sizeof(struct pci_config))
return NULL;
*reg = pci_config_addr.bits.offset;
return find_pci_device(pci_config_addr.bits.devnum);
}
/*
* We can get invalid combinations of values while they're writing, so we
* only fault if they try to write with some invalid bar/offset/length.
*/
static bool valid_bar_access(struct device *d,
struct virtio_pci_cfg_cap_u32 *cfg_access)
{
/* We only have 1 bar (BAR0) */
if (cfg_access->cap.bar != 0)
return false;
/* Check it's within BAR0. */
if (cfg_access->cap.offset >= d->mmio_size
|| cfg_access->cap.offset + cfg_access->cap.length > d->mmio_size)
return false;
/* Check length is 1, 2 or 4. */
if (cfg_access->cap.length != 1
&& cfg_access->cap.length != 2
&& cfg_access->cap.length != 4)
return false;
/*
* 4.1.4.7.2:
*
* The driver MUST NOT write a cap.offset which is not a multiple of
* cap.length (ie. all accesses MUST be aligned).
*/
if (cfg_access->cap.offset % cfg_access->cap.length != 0)
return false;
/* Return pointer into word in BAR0. */
return true;
}
/* Is this accessing the PCI config address port?. */
static bool is_pci_addr_port(u16 port)
{
return port >= PCI_CONFIG_ADDR && port < PCI_CONFIG_ADDR + 4;
}
static bool pci_addr_iowrite(u16 port, u32 mask, u32 val)
{
iowrite(port - PCI_CONFIG_ADDR, val, mask,
&pci_config_addr.val);
verbose("PCI%s: %#x/%x: bus %u dev %u func %u reg %u\n",
pci_config_addr.bits.enabled ? "" : " DISABLED",
val, mask,
pci_config_addr.bits.busnum,
pci_config_addr.bits.devnum,
pci_config_addr.bits.funcnum,
pci_config_addr.bits.offset);
return true;
}
static void pci_addr_ioread(u16 port, u32 mask, u32 *val)
{
ioread(port - PCI_CONFIG_ADDR, pci_config_addr.val, mask, val);
}
/* Is this accessing the PCI config data port?. */
static bool is_pci_data_port(u16 port)
{
return port >= PCI_CONFIG_DATA && port < PCI_CONFIG_DATA + 4;
}
static void emulate_mmio_write(struct device *d, u32 off, u32 val, u32 mask);
static bool pci_data_iowrite(u16 port, u32 mask, u32 val)
{
u32 reg, portoff;
struct device *d = dev_and_reg(®);
/* Complain if they don't belong to a device. */
if (!d)
return false;
/* They can do 1 byte writes, etc. */
portoff = port - PCI_CONFIG_DATA;
/*
* PCI uses a weird way to determine the BAR size: the OS
* writes all 1's, and sees which ones stick.
*/
if (&d->config_words[reg] == &d->config.bar[0]) {
int i;
iowrite(portoff, val, mask, &d->config.bar[0]);
for (i = 0; (1 << i) < d->mmio_size; i++)
d->config.bar[0] &= ~(1 << i);
return true;
} else if ((&d->config_words[reg] > &d->config.bar[0]
&& &d->config_words[reg] <= &d->config.bar[6])
|| &d->config_words[reg] == &d->config.expansion_rom_addr) {
/* Allow writing to any other BAR, or expansion ROM */
iowrite(portoff, val, mask, &d->config_words[reg]);
return true;
/* We let them overide latency timer and cacheline size */
} else if (&d->config_words[reg] == (void *)&d->config.cacheline_size) {
/* Only let them change the first two fields. */
if (mask == 0xFFFFFFFF)
mask = 0xFFFF;
iowrite(portoff, val, mask, &d->config_words[reg]);
return true;
} else if (&d->config_words[reg] == (void *)&d->config.command
&& mask == 0xFFFF) {
/* Ignore command writes. */
return true;
} else if (&d->config_words[reg]
== (void *)&d->config.cfg_access.cap.bar
|| &d->config_words[reg]
== &d->config.cfg_access.cap.length
|| &d->config_words[reg]
== &d->config.cfg_access.cap.offset) {
/*
* The VIRTIO_PCI_CAP_PCI_CFG capability
* provides a backdoor to access the MMIO
* regions without mapping them. Weird, but
* useful.
*/
iowrite(portoff, val, mask, &d->config_words[reg]);
return true;
} else if (&d->config_words[reg] == &d->config.cfg_access.pci_cfg_data) {
u32 write_mask;
/*
* 4.1.4.7.1:
*
* Upon detecting driver write access to pci_cfg_data, the
* device MUST execute a write access at offset cap.offset at
* BAR selected by cap.bar using the first cap.length bytes
* from pci_cfg_data.
*/
/* Must be bar 0 */
if (!valid_bar_access(d, &d->config.cfg_access))
return false;
iowrite(portoff, val, mask, &d->config.cfg_access.pci_cfg_data);
/*
* Now emulate a write. The mask we use is set by
* len, *not* this write!
*/
write_mask = (1ULL<<(8*d->config.cfg_access.cap.length)) - 1;
verbose("Window writing %#x/%#x to bar %u, offset %u len %u\n",
d->config.cfg_access.pci_cfg_data, write_mask,
d->config.cfg_access.cap.bar,
d->config.cfg_access.cap.offset,
d->config.cfg_access.cap.length);
emulate_mmio_write(d, d->config.cfg_access.cap.offset,
d->config.cfg_access.pci_cfg_data,
write_mask);
return true;
}
/*
* 4.1.4.1:
*
* The driver MUST NOT write into any field of the capability
* structure, with the exception of those with cap_type
* VIRTIO_PCI_CAP_PCI_CFG...
*/
return false;
}
static u32 emulate_mmio_read(struct device *d, u32 off, u32 mask);
static void pci_data_ioread(u16 port, u32 mask, u32 *val)
{
u32 reg;
struct device *d = dev_and_reg(®);
if (!d)
return;
/* Read through the PCI MMIO access window is special */
if (&d->config_words[reg] == &d->config.cfg_access.pci_cfg_data) {
u32 read_mask;
/*
* 4.1.4.7.1:
*
* Upon detecting driver read access to pci_cfg_data, the
* device MUST execute a read access of length cap.length at
* offset cap.offset at BAR selected by cap.bar and store the
* first cap.length bytes in pci_cfg_data.
*/
/* Must be bar 0 */
if (!valid_bar_access(d, &d->config.cfg_access))
bad_driver(d,
"Invalid cfg_access to bar%u, offset %u len %u",
d->config.cfg_access.cap.bar,
d->config.cfg_access.cap.offset,
d->config.cfg_access.cap.length);
/*
* Read into the window. The mask we use is set by
* len, *not* this read!
*/
read_mask = (1ULL<<(8*d->config.cfg_access.cap.length))-1;
d->config.cfg_access.pci_cfg_data
= emulate_mmio_read(d,
d->config.cfg_access.cap.offset,
read_mask);
verbose("Window read %#x/%#x from bar %u, offset %u len %u\n",
d->config.cfg_access.pci_cfg_data, read_mask,
d->config.cfg_access.cap.bar,
d->config.cfg_access.cap.offset,
d->config.cfg_access.cap.length);
}
ioread(port - PCI_CONFIG_DATA, d->config_words[reg], mask, val);
}
/*L:216
* This is where we emulate a handful of Guest instructions. It's ugly
* and we used to do it in the kernel but it grew over time.
*/
/*
* We use the ptrace syscall's pt_regs struct to talk about registers
* to lguest: these macros convert the names to the offsets.
*/
#define getreg(name) getreg_off(offsetof(struct user_regs_struct, name))
#define setreg(name, val) \
setreg_off(offsetof(struct user_regs_struct, name), (val))
static u32 getreg_off(size_t offset)
{
u32 r;
unsigned long args[] = { LHREQ_GETREG, offset };
if (pwrite(lguest_fd, args, sizeof(args), cpu_id) < 0)
err(1, "Getting register %u", offset);
if (pread(lguest_fd, &r, sizeof(r), cpu_id) != sizeof(r))
err(1, "Reading register %u", offset);
return r;
}
static void setreg_off(size_t offset, u32 val)
{
unsigned long args[] = { LHREQ_SETREG, offset, val };
if (pwrite(lguest_fd, args, sizeof(args), cpu_id) < 0)
err(1, "Setting register %u", offset);
}
/* Get register by instruction encoding */
static u32 getreg_num(unsigned regnum, u32 mask)
{
/* 8 bit ops use regnums 4-7 for high parts of word */
if (mask == 0xFF && (regnum & 0x4))
return getreg_num(regnum & 0x3, 0xFFFF) >> 8;
switch (regnum) {
case 0: return getreg(eax) & mask;
case 1: return getreg(ecx) & mask;
case 2: return getreg(edx) & mask;
case 3: return getreg(ebx) & mask;
case 4: return getreg(esp) & mask;
case 5: return getreg(ebp) & mask;
case 6: return getreg(esi) & mask;
case 7: return getreg(edi) & mask;
}
abort();
}
/* Set register by instruction encoding */
static void setreg_num(unsigned regnum, u32 val, u32 mask)
{
/* Don't try to set bits out of range */
assert(~(val & ~mask));
/* 8 bit ops use regnums 4-7 for high parts of word */
if (mask == 0xFF && (regnum & 0x4)) {
/* Construct the 16 bits we want. */
val = (val << 8) | getreg_num(regnum & 0x3, 0xFF);
setreg_num(regnum & 0x3, val, 0xFFFF);
return;
}
switch (regnum) {
case 0: setreg(eax, val | (getreg(eax) & ~mask)); return;
case 1: setreg(ecx, val | (getreg(ecx) & ~mask)); return;
case 2: setreg(edx, val | (getreg(edx) & ~mask)); return;
case 3: setreg(ebx, val | (getreg(ebx) & ~mask)); return;
case 4: setreg(esp, val | (getreg(esp) & ~mask)); return;
case 5: setreg(ebp, val | (getreg(ebp) & ~mask)); return;
case 6: setreg(esi, val | (getreg(esi) & ~mask)); return;
case 7: setreg(edi, val | (getreg(edi) & ~mask)); return;
}
abort();
}
/* Get bytes of displacement appended to instruction, from r/m encoding */
static u32 insn_displacement_len(u8 mod_reg_rm)
{
/* Switch on the mod bits */
switch (mod_reg_rm >> 6) {
case 0:
/* If mod == 0, and r/m == 101, 16-bit displacement follows */
if ((mod_reg_rm & 0x7) == 0x5)
return 2;
/* Normally, mod == 0 means no literal displacement */
return 0;
case 1:
/* One byte displacement */
return 1;
case 2:
/* Four byte displacement */
return 4;
case 3:
/* Register mode */
return 0;
}
abort();
}
static void emulate_insn(const u8 insn[])
{
unsigned long args[] = { LHREQ_TRAP, 13 };
unsigned int insnlen = 0, in = 0, small_operand = 0, byte_access;
unsigned int eax, port, mask;
/*
* Default is to return all-ones on IO port reads, which traditionally
* means "there's nothing there".
*/
u32 val = 0xFFFFFFFF;
/*
* This must be the Guest kernel trying to do something, not userspace!
* The bottom two bits of the CS segment register are the privilege
* level.
*/
if ((getreg(xcs) & 3) != 0x1)
goto no_emulate;
/* Decoding x86 instructions is icky. */
/*
* Around 2.6.33, the kernel started using an emulation for the
* cmpxchg8b instruction in early boot on many configurations. This
* code isn't paravirtualized, and it tries to disable interrupts.
* Ignore it, which will Mostly Work.
*/
if (insn[insnlen] == 0xfa) {
/* "cli", or Clear Interrupt Enable instruction. Skip it. */
insnlen = 1;
goto skip_insn;
}
/*
* 0x66 is an "operand prefix". It means a 16, not 32 bit in/out.
*/
if (insn[insnlen] == 0x66) {
small_operand = 1;
/* The instruction is 1 byte so far, read the next byte. */
insnlen = 1;
}
/* If the lower bit isn't set, it's a single byte access */
byte_access = !(insn[insnlen] & 1);
/*
* Now we can ignore the lower bit and decode the 4 opcodes
* we need to emulate.
*/
switch (insn[insnlen] & 0xFE) {
case 0xE4: /* in <next byte>,%al */
port = insn[insnlen+1];
insnlen += 2;
in = 1;
break;
case 0xEC: /* in (%dx),%al */
port = getreg(edx) & 0xFFFF;
insnlen += 1;
in = 1;
break;
case 0xE6: /* out %al,<next byte> */
port = insn[insnlen+1];
insnlen += 2;
break;
case 0xEE: /* out %al,(%dx) */
port = getreg(edx) & 0xFFFF;
insnlen += 1;
break;
default:
/* OK, we don't know what this is, can't emulate. */
goto no_emulate;
}
/* Set a mask of the 1, 2 or 4 bytes, depending on size of IO */
if (byte_access)
mask = 0xFF;
else if (small_operand)
mask = 0xFFFF;
else
mask = 0xFFFFFFFF;
/*
* If it was an "IN" instruction, they expect the result to be read
* into %eax, so we change %eax.
*/
eax = getreg(eax);
if (in) {
/* This is the PS/2 keyboard status; 1 means ready for output */
if (port == 0x64)
val = 1;
else if (is_pci_addr_port(port))
pci_addr_ioread(port, mask, &val);
else if (is_pci_data_port(port))
pci_data_ioread(port, mask, &val);
/* Clear the bits we're about to read */
eax &= ~mask;
/* Copy bits in from val. */
eax |= val & mask;
/* Now update the register. */
setreg(eax, eax);
} else {
if (is_pci_addr_port(port)) {
if (!pci_addr_iowrite(port, mask, eax))
goto bad_io;
} else if (is_pci_data_port(port)) {
if (!pci_data_iowrite(port, mask, eax))
goto bad_io;
}
/* There are many other ports, eg. CMOS clock, serial
* and parallel ports, so we ignore them all. */
}
verbose("IO %s of %x to %u: %#08x\n",
in ? "IN" : "OUT", mask, port, eax);
skip_insn:
/* Finally, we've "done" the instruction, so move past it. */
setreg(eip, getreg(eip) + insnlen);
return;
bad_io:
warnx("Attempt to %s port %u (%#x mask)",
in ? "read from" : "write to", port, mask);
no_emulate:
/* Inject trap into Guest. */
if (write(lguest_fd, args, sizeof(args)) < 0)
err(1, "Reinjecting trap 13 for fault at %#x", getreg(eip));
}
static struct device *find_mmio_region(unsigned long paddr, u32 *off)
{
unsigned int i;
for (i = 1; i < MAX_PCI_DEVICES; i++) {
struct device *d = devices.pci[i];
if (!d)
continue;
if (paddr < d->mmio_addr)
continue;
if (paddr >= d->mmio_addr + d->mmio_size)
continue;
*off = paddr - d->mmio_addr;
return d;
}
return NULL;
}
/* FIXME: Use vq array. */
static struct virtqueue *vq_by_num(struct device *d, u32 num)
{
struct virtqueue *vq = d->vq;
while (num-- && vq)
vq = vq->next;
return vq;
}
static void save_vq_config(const struct virtio_pci_common_cfg *cfg,
struct virtqueue *vq)
{
vq->pci_config = *cfg;
}
static void restore_vq_config(struct virtio_pci_common_cfg *cfg,
struct virtqueue *vq)
{
/* Only restore the per-vq part */
size_t off = offsetof(struct virtio_pci_common_cfg, queue_size);
memcpy((void *)cfg + off, (void *)&vq->pci_config + off,
sizeof(*cfg) - off);
}
/*
* 4.1.4.3.2:
*
* The driver MUST configure the other virtqueue fields before
* enabling the virtqueue with queue_enable.
*
* When they enable the virtqueue, we check that their setup is valid.
*/
static void check_virtqueue(struct device *d, struct virtqueue *vq)
{
/* Because lguest is 32 bit, all the descriptor high bits must be 0 */
if (vq->pci_config.queue_desc_hi
|| vq->pci_config.queue_avail_hi
|| vq->pci_config.queue_used_hi)
bad_driver_vq(vq, "invalid 64-bit queue address");
/*
* 2.4.1:
*
* The driver MUST ensure that the physical address of the first byte
* of each virtqueue part is a multiple of the specified alignment
* value in the above table.
*/
if (vq->pci_config.queue_desc_lo % 16
|| vq->pci_config.queue_avail_lo % 2
|| vq->pci_config.queue_used_lo % 4)
bad_driver_vq(vq, "invalid alignment in queue addresses");
/* Initialize the virtqueue and check they're all in range. */
vq->vring.num = vq->pci_config.queue_size;
vq->vring.desc = check_pointer(vq->dev,
vq->pci_config.queue_desc_lo,
sizeof(*vq->vring.desc) * vq->vring.num);
vq->vring.avail = check_pointer(vq->dev,
vq->pci_config.queue_avail_lo,
sizeof(*vq->vring.avail)
+ (sizeof(vq->vring.avail->ring[0])
* vq->vring.num));
vq->vring.used = check_pointer(vq->dev,
vq->pci_config.queue_used_lo,
sizeof(*vq->vring.used)
+ (sizeof(vq->vring.used->ring[0])
* vq->vring.num));
/*
* 2.4.9.1:
*
* The driver MUST initialize flags in the used ring to 0
* when allocating the used ring.
*/
if (vq->vring.used->flags != 0)
bad_driver_vq(vq, "invalid initial used.flags %#x",
vq->vring.used->flags);
}
static void start_virtqueue(struct virtqueue *vq)
{
/*
* Create stack for thread. Since the stack grows upwards, we point
* the stack pointer to the end of this region.
*/
char *stack = malloc(32768);
/* Create a zero-initialized eventfd. */
vq->eventfd = eventfd(0, 0);
if (vq->eventfd < 0)
err(1, "Creating eventfd");
/*
* CLONE_VM: because it has to access the Guest memory, and SIGCHLD so
* we get a signal if it dies.
*/
vq->thread = clone(do_thread, stack + 32768, CLONE_VM | SIGCHLD, vq);
if (vq->thread == (pid_t)-1)
err(1, "Creating clone");
}
static void start_virtqueues(struct device *d)
{
struct virtqueue *vq;
for (vq = d->vq; vq; vq = vq->next) {
if (vq->pci_config.queue_enable)
start_virtqueue(vq);
}
}
static void emulate_mmio_write(struct device *d, u32 off, u32 val, u32 mask)
{
struct virtqueue *vq;
switch (off) {
case offsetof(struct virtio_pci_mmio, cfg.device_feature_select):
/*
* 4.1.4.3.1:
*
* The device MUST present the feature bits it is offering in
* device_feature, starting at bit device_feature_select ∗ 32
* for any device_feature_select written by the driver
*/
if (val == 0)
d->mmio->cfg.device_feature = d->features;
else if (val == 1)
d->mmio->cfg.device_feature = (d->features >> 32);
else
d->mmio->cfg.device_feature = 0;
goto feature_write_through32;
case offsetof(struct virtio_pci_mmio, cfg.guest_feature_select):
if (val > 1)
bad_driver(d, "Unexpected driver select %u", val);
goto feature_write_through32;
case offsetof(struct virtio_pci_mmio, cfg.guest_feature):
if (d->mmio->cfg.guest_feature_select == 0) {
d->features_accepted &= ~((u64)0xFFFFFFFF);
d->features_accepted |= val;
} else {
assert(d->mmio->cfg.guest_feature_select == 1);
d->features_accepted &= 0xFFFFFFFF;
d->features_accepted |= ((u64)val) << 32;
}
/*
* 2.2.1:
*
* The driver MUST NOT accept a feature which the device did
* not offer
*/
if (d->features_accepted & ~d->features)
bad_driver(d, "over-accepted features %#llx of %#llx",
d->features_accepted, d->features);
goto feature_write_through32;
case offsetof(struct virtio_pci_mmio, cfg.device_status): {
u8 prev;
verbose("%s: device status -> %#x\n", d->name, val);
/*
* 4.1.4.3.1:
*
* The device MUST reset when 0 is written to device_status,
* and present a 0 in device_status once that is done.
*/
if (val == 0) {
reset_device(d);
goto write_through8;
}
/* 2.1.1: The driver MUST NOT clear a device status bit. */
if (d->mmio->cfg.device_status & ~val)
bad_driver(d, "unset of device status bit %#x -> %#x",
d->mmio->cfg.device_status, val);
/*
* 2.1.2:
*
* The device MUST NOT consume buffers or notify the driver
* before DRIVER_OK.
*/
if (val & VIRTIO_CONFIG_S_DRIVER_OK
&& !(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER_OK))
start_virtqueues(d);
/*
* 3.1.1:
*
* The driver MUST follow this sequence to initialize a device:
* - Reset the device.
* - Set the ACKNOWLEDGE status bit: the guest OS has
* notice the device.
* - Set the DRIVER status bit: the guest OS knows how
* to drive the device.
* - Read device feature bits, and write the subset
* of feature bits understood by the OS and driver
* to the device. During this step the driver MAY
* read (but MUST NOT write) the device-specific
* configuration fields to check that it can
* support the device before accepting it.
* - Set the FEATURES_OK status bit. The driver
* MUST not accept new feature bits after this
* step.
* - Re-read device status to ensure the FEATURES_OK
* bit is still set: otherwise, the device does
* not support our subset of features and the
* device is unusable.
* - Perform device-specific setup, including
* discovery of virtqueues for the device,
* optional per-bus setup, reading and possibly
* writing the device’s virtio configuration
* space, and population of virtqueues.
* - Set the DRIVER_OK status bit. At this point the
* device is “live”.
*/
prev = 0;
switch (val & ~d->mmio->cfg.device_status) {
case VIRTIO_CONFIG_S_DRIVER_OK:
prev |= VIRTIO_CONFIG_S_FEATURES_OK; /* fall thru */
case VIRTIO_CONFIG_S_FEATURES_OK:
prev |= VIRTIO_CONFIG_S_DRIVER; /* fall thru */
case VIRTIO_CONFIG_S_DRIVER:
prev |= VIRTIO_CONFIG_S_ACKNOWLEDGE; /* fall thru */
case VIRTIO_CONFIG_S_ACKNOWLEDGE:
break;
default:
bad_driver(d, "unknown device status bit %#x -> %#x",
d->mmio->cfg.device_status, val);
}
if (d->mmio->cfg.device_status != prev)
bad_driver(d, "unexpected status transition %#x -> %#x",
d->mmio->cfg.device_status, val);
/* If they just wrote FEATURES_OK, we make sure they read */
switch (val & ~d->mmio->cfg.device_status) {
case VIRTIO_CONFIG_S_FEATURES_OK:
d->wrote_features_ok = true;
break;
case VIRTIO_CONFIG_S_DRIVER_OK:
if (d->wrote_features_ok)
bad_driver(d, "did not re-read FEATURES_OK");
break;
}
goto write_through8;
}
case offsetof(struct virtio_pci_mmio, cfg.queue_select):
vq = vq_by_num(d, val);
/*
* 4.1.4.3.1:
*
* The device MUST present a 0 in queue_size if the virtqueue
* corresponding to the current queue_select is unavailable.
*/
if (!vq) {
d->mmio->cfg.queue_size = 0;
goto write_through16;
}
/* Save registers for old vq, if it was a valid vq */
if (d->mmio->cfg.queue_size)
save_vq_config(&d->mmio->cfg,
vq_by_num(d, d->mmio->cfg.queue_select));
/* Restore the registers for the queue they asked for */
restore_vq_config(&d->mmio->cfg, vq);
goto write_through16;
case offsetof(struct virtio_pci_mmio, cfg.queue_size):
/*
* 4.1.4.3.2:
*
* The driver MUST NOT write a value which is not a power of 2
* to queue_size.
*/
if (val & (val-1))
bad_driver(d, "invalid queue size %u", val);
if (d->mmio->cfg.queue_enable)
bad_driver(d, "changing queue size on live device");
goto write_through16;
case offsetof(struct virtio_pci_mmio, cfg.queue_msix_vector):
bad_driver(d, "attempt to set MSIX vector to %u", val);
case offsetof(struct virtio_pci_mmio, cfg.queue_enable): {
struct virtqueue *vq = vq_by_num(d, d->mmio->cfg.queue_select);
/*
* 4.1.4.3.2:
*
* The driver MUST NOT write a 0 to queue_enable.
*/
if (val != 1)
bad_driver(d, "setting queue_enable to %u", val);
/*
* 3.1.1:
*
* 7. Perform device-specific setup, including discovery of
* virtqueues for the device, optional per-bus setup,
* reading and possibly writing the device’s virtio
* configuration space, and population of virtqueues.
* 8. Set the DRIVER_OK status bit.
*
* All our devices require all virtqueues to be enabled, so
* they should have done that before setting DRIVER_OK.
*/
if (d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER_OK)
bad_driver(d, "enabling vq after DRIVER_OK");
d->mmio->cfg.queue_enable = val;
save_vq_config(&d->mmio->cfg, vq);
check_virtqueue(d, vq);
goto write_through16;
}
case offsetof(struct virtio_pci_mmio, cfg.queue_notify_off):
bad_driver(d, "attempt to write to queue_notify_off");
case offsetof(struct virtio_pci_mmio, cfg.queue_desc_lo):
case offsetof(struct virtio_pci_mmio, cfg.queue_desc_hi):
case offsetof(struct virtio_pci_mmio, cfg.queue_avail_lo):
case offsetof(struct virtio_pci_mmio, cfg.queue_avail_hi):
case offsetof(struct virtio_pci_mmio, cfg.queue_used_lo):
case offsetof(struct virtio_pci_mmio, cfg.queue_used_hi):
/*
* 4.1.4.3.2:
*
* The driver MUST configure the other virtqueue fields before
* enabling the virtqueue with queue_enable.
*/
if (d->mmio->cfg.queue_enable)
bad_driver(d, "changing queue on live device");
/*
* 3.1.1:
*
* The driver MUST follow this sequence to initialize a device:
*...
* 5. Set the FEATURES_OK status bit. The driver MUST not
* accept new feature bits after this step.
*/
if (!(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_FEATURES_OK))
bad_driver(d, "setting up vq before FEATURES_OK");
/*
* 6. Re-read device status to ensure the FEATURES_OK bit is
* still set...
*/
if (d->wrote_features_ok)
bad_driver(d, "didn't re-read FEATURES_OK before setup");
goto write_through32;
case offsetof(struct virtio_pci_mmio, notify):
vq = vq_by_num(d, val);
if (!vq)
bad_driver(d, "Invalid vq notification on %u", val);
/* Notify the process handling this vq by adding 1 to eventfd */
write(vq->eventfd, "\1\0\0\0\0\0\0\0", 8);
goto write_through16;
case offsetof(struct virtio_pci_mmio, isr):
bad_driver(d, "Unexpected write to isr");
/* Weird corner case: write to emerg_wr of console */
case sizeof(struct virtio_pci_mmio)
+ offsetof(struct virtio_console_config, emerg_wr):
if (strcmp(d->name, "console") == 0) {
char c = val;
write(STDOUT_FILENO, &c, 1);
goto write_through32;
}
/* Fall through... */
default:
/*
* 4.1.4.3.2:
*
* The driver MUST NOT write to device_feature, num_queues,
* config_generation or queue_notify_off.
*/
bad_driver(d, "Unexpected write to offset %u", off);
}
feature_write_through32:
/*
* 3.1.1:
*
* The driver MUST follow this sequence to initialize a device:
*...
* - Set the DRIVER status bit: the guest OS knows how
* to drive the device.
* - Read device feature bits, and write the subset
* of feature bits understood by the OS and driver
* to the device.
*...
* - Set the FEATURES_OK status bit. The driver MUST not
* accept new feature bits after this step.
*/
if (!(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER))
bad_driver(d, "feature write before VIRTIO_CONFIG_S_DRIVER");
if (d->mmio->cfg.device_status & VIRTIO_CONFIG_S_FEATURES_OK)
bad_driver(d, "feature write after VIRTIO_CONFIG_S_FEATURES_OK");
/*
* 4.1.3.1:
*
* The driver MUST access each field using the “natural” access
* method, i.e. 32-bit accesses for 32-bit fields, 16-bit accesses for
* 16-bit fields and 8-bit accesses for 8-bit fields.
*/
write_through32:
if (mask != 0xFFFFFFFF) {
bad_driver(d, "non-32-bit write to offset %u (%#x)",
off, getreg(eip));
return;
}
memcpy((char *)d->mmio + off, &val, 4);
return;
write_through16:
if (mask != 0xFFFF)
bad_driver(d, "non-16-bit write to offset %u (%#x)",
off, getreg(eip));
memcpy((char *)d->mmio + off, &val, 2);
return;
write_through8:
if (mask != 0xFF)
bad_driver(d, "non-8-bit write to offset %u (%#x)",
off, getreg(eip));
memcpy((char *)d->mmio + off, &val, 1);
return;
}
static u32 emulate_mmio_read(struct device *d, u32 off, u32 mask)
{
u8 isr;
u32 val = 0;
switch (off) {
case offsetof(struct virtio_pci_mmio, cfg.device_feature_select):
case offsetof(struct virtio_pci_mmio, cfg.device_feature):
case offsetof(struct virtio_pci_mmio, cfg.guest_feature_select):
case offsetof(struct virtio_pci_mmio, cfg.guest_feature):
/*
* 3.1.1:
*
* The driver MUST follow this sequence to initialize a device:
*...
* - Set the DRIVER status bit: the guest OS knows how
* to drive the device.
* - Read device feature bits, and write the subset
* of feature bits understood by the OS and driver
* to the device.
*/
if (!(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER))
bad_driver(d,
"feature read before VIRTIO_CONFIG_S_DRIVER");
goto read_through32;
case offsetof(struct virtio_pci_mmio, cfg.msix_config):
bad_driver(d, "read of msix_config");
case offsetof(struct virtio_pci_mmio, cfg.num_queues):
goto read_through16;
case offsetof(struct virtio_pci_mmio, cfg.device_status):
/* As they did read, any write of FEATURES_OK is now fine. */
d->wrote_features_ok = false;
goto read_through8;
case offsetof(struct virtio_pci_mmio, cfg.config_generation):
/*
* 4.1.4.3.1:
*
* The device MUST present a changed config_generation after
* the driver has read a device-specific configuration value
* which has changed since any part of the device-specific
* configuration was last read.
*
* This is simple: none of our devices change config, so this
* is always 0.
*/
goto read_through8;
case offsetof(struct virtio_pci_mmio, notify):
/*
* 3.1.1:
*
* The driver MUST NOT notify the device before setting
* DRIVER_OK.
*/
if (!(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER_OK))
bad_driver(d, "notify before VIRTIO_CONFIG_S_DRIVER_OK");
goto read_through16;
case offsetof(struct virtio_pci_mmio, isr):
if (mask != 0xFF)
bad_driver(d, "non-8-bit read from offset %u (%#x)",
off, getreg(eip));
isr = d->mmio->isr;
/*
* 4.1.4.5.1:
*
* The device MUST reset ISR status to 0 on driver read.
*/
d->mmio->isr = 0;
return isr;
case offsetof(struct virtio_pci_mmio, padding):
bad_driver(d, "read from padding (%#x)", getreg(eip));
default:
/* Read from device config space, beware unaligned overflow */
if (off > d->mmio_size - 4)
bad_driver(d, "read past end (%#x)", getreg(eip));
/*
* 3.1.1:
* The driver MUST follow this sequence to initialize a device:
*...
* 3. Set the DRIVER status bit: the guest OS knows how to
* drive the device.
* 4. Read device feature bits, and write the subset of
* feature bits understood by the OS and driver to the
* device. During this step the driver MAY read (but MUST NOT
* write) the device-specific configuration fields to check
* that it can support the device before accepting it.
*/
if (!(d->mmio->cfg.device_status & VIRTIO_CONFIG_S_DRIVER))
bad_driver(d,
"config read before VIRTIO_CONFIG_S_DRIVER");
if (mask == 0xFFFFFFFF)
goto read_through32;
else if (mask == 0xFFFF)
goto read_through16;
else
goto read_through8;
}
/*
* 4.1.3.1:
*
* The driver MUST access each field using the “natural” access
* method, i.e. 32-bit accesses for 32-bit fields, 16-bit accesses for
* 16-bit fields and 8-bit accesses for 8-bit fields.
*/
read_through32:
if (mask != 0xFFFFFFFF)
bad_driver(d, "non-32-bit read to offset %u (%#x)",
off, getreg(eip));
memcpy(&val, (char *)d->mmio + off, 4);
return val;
read_through16:
if (mask != 0xFFFF)
bad_driver(d, "non-16-bit read to offset %u (%#x)",
off, getreg(eip));
memcpy(&val, (char *)d->mmio + off, 2);
return val;
read_through8:
if (mask != 0xFF)
bad_driver(d, "non-8-bit read to offset %u (%#x)",
off, getreg(eip));
memcpy(&val, (char *)d->mmio + off, 1);
return val;
}
static void emulate_mmio(unsigned long paddr, const u8 *insn)
{
u32 val, off, mask = 0xFFFFFFFF, insnlen = 0;
struct device *d = find_mmio_region(paddr, &off);
unsigned long args[] = { LHREQ_TRAP, 14 };
if (!d) {
warnx("MMIO touching %#08lx (not a device)", paddr);
goto reinject;
}
/* Prefix makes it a 16 bit op */
if (insn[0] == 0x66) {
mask = 0xFFFF;
insnlen++;
}
/* iowrite */
if (insn[insnlen] == 0x89) {
/* Next byte is r/m byte: bits 3-5 are register. */
val = getreg_num((insn[insnlen+1] >> 3) & 0x7, mask);
emulate_mmio_write(d, off, val, mask);
insnlen += 2 + insn_displacement_len(insn[insnlen+1]);
} else if (insn[insnlen] == 0x8b) { /* ioread */
/* Next byte is r/m byte: bits 3-5 are register. */
val = emulate_mmio_read(d, off, mask);
setreg_num((insn[insnlen+1] >> 3) & 0x7, val, mask);
insnlen += 2 + insn_displacement_len(insn[insnlen+1]);
} else if (insn[0] == 0x88) { /* 8-bit iowrite */
mask = 0xff;
/* Next byte is r/m byte: bits 3-5 are register. */
val = getreg_num((insn[1] >> 3) & 0x7, mask);
emulate_mmio_write(d, off, val, mask);
insnlen = 2 + insn_displacement_len(insn[1]);
} else if (insn[0] == 0x8a) { /* 8-bit ioread */
mask = 0xff;
val = emulate_mmio_read(d, off, mask);
setreg_num((insn[1] >> 3) & 0x7, val, mask);
insnlen = 2 + insn_displacement_len(insn[1]);
} else {
warnx("Unknown MMIO instruction touching %#08lx:"
" %02x %02x %02x %02x at %u",
paddr, insn[0], insn[1], insn[2], insn[3], getreg(eip));
reinject:
/* Inject trap into Guest. */
if (write(lguest_fd, args, sizeof(args)) < 0)
err(1, "Reinjecting trap 14 for fault at %#x",
getreg(eip));
return;
}
/* Finally, we've "done" the instruction, so move past it. */
setreg(eip, getreg(eip) + insnlen);
}
/*L:190
* Device Setup
*
* All devices need a descriptor so the Guest knows it exists, and a "struct
* device" so the Launcher can keep track of it. We have common helper
* routines to allocate and manage them.
*/
static void add_pci_virtqueue(struct device *dev,
void (*service)(struct virtqueue *),
const char *name)
{
struct virtqueue **i, *vq = malloc(sizeof(*vq));
/* Initialize the virtqueue */
vq->next = NULL;
vq->last_avail_idx = 0;
vq->dev = dev;
vq->name = name;
/*
* This is the routine the service thread will run, and its Process ID
* once it's running.
*/
vq->service = service;
vq->thread = (pid_t)-1;
/* Initialize the configuration. */
reset_vq_pci_config(vq);
vq->pci_config.queue_notify_off = 0;
/* Add one to the number of queues */
vq->dev->mmio->cfg.num_queues++;
/*
* Add to tail of list, so dev->vq is first vq, dev->vq->next is
* second.
*/
for (i = &dev->vq; *i; i = &(*i)->next);
*i = vq;
}
/* The Guest accesses the feature bits via the PCI common config MMIO region */
static void add_pci_feature(struct device *dev, unsigned bit)
{
dev->features |= (1ULL << bit);
}
/* For devices with no config. */
static void no_device_config(struct device *dev)
{
dev->mmio_addr = get_mmio_region(dev->mmio_size);
dev->config.bar[0] = dev->mmio_addr;
/* Bottom 4 bits must be zero */
assert(~(dev->config.bar[0] & 0xF));
}
/* This puts the device config into BAR0 */
static void set_device_config(struct device *dev, const void *conf, size_t len)
{
/* Set up BAR 0 */
dev->mmio_size += len;
dev->mmio = realloc(dev->mmio, dev->mmio_size);
memcpy(dev->mmio + 1, conf, len);
/*
* 4.1.4.6:
*
* The device MUST present at least one VIRTIO_PCI_CAP_DEVICE_CFG
* capability for any device type which has a device-specific
* configuration.
*/
/* Hook up device cfg */
dev->config.cfg_access.cap.cap_next
= offsetof(struct pci_config, device);
/*
* 4.1.4.6.1:
*
* The offset for the device-specific configuration MUST be 4-byte
* aligned.
*/
assert(dev->config.cfg_access.cap.cap_next % 4 == 0);
/* Fix up device cfg field length. */
dev->config.device.length = len;
/* The rest is the same as the no-config case */
no_device_config(dev);
}
static void init_cap(struct virtio_pci_cap *cap, size_t caplen, int type,
size_t bar_offset, size_t bar_bytes, u8 next)
{
cap->cap_vndr = PCI_CAP_ID_VNDR;
cap->cap_next = next;
cap->cap_len = caplen;
cap->cfg_type = type;
cap->bar = 0;
memset(cap->padding, 0, sizeof(cap->padding));
cap->offset = bar_offset;
cap->length = bar_bytes;
}
/*
* This sets up the pci_config structure, as defined in the virtio 1.0
* standard (and PCI standard).
*/
static void init_pci_config(struct pci_config *pci, u16 type,
u8 class, u8 subclass)
{
size_t bar_offset, bar_len;
/*
* 4.1.4.4.1:
*
* The device MUST either present notify_off_multiplier as an even
* power of 2, or present notify_off_multiplier as 0.
*
* 2.1.2:
*
* The device MUST initialize device status to 0 upon reset.
*/
memset(pci, 0, sizeof(*pci));
/* 4.1.2.1: Devices MUST have the PCI Vendor ID 0x1AF4 */
pci->vendor_id = 0x1AF4;
/* 4.1.2.1: ... PCI Device ID calculated by adding 0x1040 ... */
pci->device_id = 0x1040 + type;
/*
* PCI have specific codes for different types of devices.
* Linux doesn't care, but it's a good clue for people looking
* at the device.
*/
pci->class = class;
pci->subclass = subclass;
/*
* 4.1.2.1:
*
* Non-transitional devices SHOULD have a PCI Revision ID of 1 or
* higher
*/
pci->revid = 1;
/*
* 4.1.2.1:
*
* Non-transitional devices SHOULD have a PCI Subsystem Device ID of
* 0x40 or higher.
*/
pci->subsystem_device_id = 0x40;
/* We use our dummy interrupt controller, and irq_line is the irq */
pci->irq_line = devices.next_irq++;
pci->irq_pin = 0;
/* Support for extended capabilities. */
pci->status = (1 << 4);
/* Link them in. */
/*
* 4.1.4.3.1:
*
* The device MUST present at least one common configuration
* capability.
*/
pci->capabilities = offsetof(struct pci_config, common);
/* 4.1.4.3.1 ... offset MUST be 4-byte aligned. */
assert(pci->capabilities % 4 == 0);
bar_offset = offsetof(struct virtio_pci_mmio, cfg);
bar_len = sizeof(((struct virtio_pci_mmio *)0)->cfg);
init_cap(&pci->common, sizeof(pci->common), VIRTIO_PCI_CAP_COMMON_CFG,
bar_offset, bar_len,
offsetof(struct pci_config, notify));
/*
* 4.1.4.4.1:
*
* The device MUST present at least one notification capability.
*/
bar_offset += bar_len;
bar_len = sizeof(((struct virtio_pci_mmio *)0)->notify);
/*
* 4.1.4.4.1:
*
* The cap.offset MUST be 2-byte aligned.
*/
assert(pci->common.cap_next % 2 == 0);
/* FIXME: Use a non-zero notify_off, for per-queue notification? */
/*
* 4.1.4.4.1:
*
* The value cap.length presented by the device MUST be at least 2 and
* MUST be large enough to support queue notification offsets for all
* supported queues in all possible configurations.
*/
assert(bar_len >= 2);
init_cap(&pci->notify.cap, sizeof(pci->notify),
VIRTIO_PCI_CAP_NOTIFY_CFG,
bar_offset, bar_len,
offsetof(struct pci_config, isr));
bar_offset += bar_len;
bar_len = sizeof(((struct virtio_pci_mmio *)0)->isr);
/*
* 4.1.4.5.1:
*
* The device MUST present at least one VIRTIO_PCI_CAP_ISR_CFG
* capability.
*/
init_cap(&pci->isr, sizeof(pci->isr),
VIRTIO_PCI_CAP_ISR_CFG,
bar_offset, bar_len,
offsetof(struct pci_config, cfg_access));
/*
* 4.1.4.7.1:
*
* The device MUST present at least one VIRTIO_PCI_CAP_PCI_CFG
* capability.
*/
/* This doesn't have any presence in the BAR */
init_cap(&pci->cfg_access.cap, sizeof(pci->cfg_access),
VIRTIO_PCI_CAP_PCI_CFG,
0, 0, 0);
bar_offset += bar_len + sizeof(((struct virtio_pci_mmio *)0)->padding);
assert(bar_offset == sizeof(struct virtio_pci_mmio));
/*
* This gets sewn in and length set in set_device_config().
* Some devices don't have a device configuration interface, so
* we never expose this if we don't call set_device_config().
*/
init_cap(&pci->device, sizeof(pci->device), VIRTIO_PCI_CAP_DEVICE_CFG,
bar_offset, 0, 0);
}
/*
* This routine does all the creation and setup of a new device, but we don't
* actually place the MMIO region until we know the size (if any) of the
* device-specific config. And we don't actually start the service threads
* until later.
*
* See what I mean about userspace being boring?
*/
static struct device *new_pci_device(const char *name, u16 type,
u8 class, u8 subclass)
{
struct device *dev = malloc(sizeof(*dev));
/* Now we populate the fields one at a time. */
dev->name = name;
dev->vq = NULL;
dev->running = false;
dev->wrote_features_ok = false;
dev->mmio_size = sizeof(struct virtio_pci_mmio);
dev->mmio = calloc(1, dev->mmio_size);
dev->features = (u64)1 << VIRTIO_F_VERSION_1;
dev->features_accepted = 0;
if (devices.device_num + 1 >= MAX_PCI_DEVICES)
errx(1, "Can only handle 31 PCI devices");
init_pci_config(&dev->config, type, class, subclass);
assert(!devices.pci[devices.device_num+1]);
devices.pci[++devices.device_num] = dev;
return dev;
}
/*
* Our first setup routine is the console. It's a fairly simple device, but
* UNIX tty handling makes it uglier than it could be.
*/
static void setup_console(void)
{
struct device *dev;
struct virtio_console_config conf;
/* If we can save the initial standard input settings... */
if (tcgetattr(STDIN_FILENO, &orig_term) == 0) {
struct termios term = orig_term;
/*
* Then we turn off echo, line buffering and ^C etc: We want a
* raw input stream to the Guest.
*/
term.c_lflag &= ~(ISIG|ICANON|ECHO);
tcsetattr(STDIN_FILENO, TCSANOW, &term);
}
dev = new_pci_device("console", VIRTIO_ID_CONSOLE, 0x07, 0x00);
/* We store the console state in dev->priv, and initialize it. */
dev->priv = malloc(sizeof(struct console_abort));
((struct console_abort *)dev->priv)->count = 0;
/*
* The console needs two virtqueues: the input then the output. When
* they put something the input queue, we make sure we're listening to
* stdin. When they put something in the output queue, we write it to
* stdout.
*/
add_pci_virtqueue(dev, console_input, "input");
add_pci_virtqueue(dev, console_output, "output");
/* We need a configuration area for the emerg_wr early writes. */
add_pci_feature(dev, VIRTIO_CONSOLE_F_EMERG_WRITE);
set_device_config(dev, &conf, sizeof(conf));
verbose("device %u: console\n", devices.device_num);
}
/*:*/
/*M:010
* Inter-guest networking is an interesting area. Simplest is to have a
* --sharenet=<name> option which opens or creates a named pipe. This can be
* used to send packets to another guest in a 1:1 manner.
*
* More sophisticated is to use one of the tools developed for project like UML
* to do networking.
*
* Faster is to do virtio bonding in kernel. Doing this 1:1 would be
* completely generic ("here's my vring, attach to your vring") and would work
* for any traffic. Of course, namespace and permissions issues need to be
* dealt with. A more sophisticated "multi-channel" virtio_net.c could hide
* multiple inter-guest channels behind one interface, although it would
* require some manner of hotplugging new virtio channels.
*
* Finally, we could use a virtio network switch in the kernel, ie. vhost.
:*/
static u32 str2ip(const char *ipaddr)
{
unsigned int b[4];
if (sscanf(ipaddr, "%u.%u.%u.%u", &b[0], &b[1], &b[2], &b[3]) != 4)
errx(1, "Failed to parse IP address '%s'", ipaddr);
return (b[0] << 24) | (b[1] << 16) | (b[2] << 8) | b[3];
}
static void str2mac(const char *macaddr, unsigned char mac[6])
{
unsigned int m[6];
if (sscanf(macaddr, "%02x:%02x:%02x:%02x:%02x:%02x",
&m[0], &m[1], &m[2], &m[3], &m[4], &m[5]) != 6)
errx(1, "Failed to parse mac address '%s'", macaddr);
mac[0] = m[0];
mac[1] = m[1];
mac[2] = m[2];
mac[3] = m[3];
mac[4] = m[4];
mac[5] = m[5];
}
/*
* This code is "adapted" from libbridge: it attaches the Host end of the
* network device to the bridge device specified by the command line.
*
* This is yet another James Morris contribution (I'm an IP-level guy, so I
* dislike bridging), and I just try not to break it.
*/
static void add_to_bridge(int fd, const char *if_name, const char *br_name)
{
int ifidx;
struct ifreq ifr;
if (!*br_name)
errx(1, "must specify bridge name");
ifidx = if_nametoindex(if_name);
if (!ifidx)
errx(1, "interface %s does not exist!", if_name);
strncpy(ifr.ifr_name, br_name, IFNAMSIZ);
ifr.ifr_name[IFNAMSIZ-1] = '\0';
ifr.ifr_ifindex = ifidx;
if (ioctl(fd, SIOCBRADDIF, &ifr) < 0)
err(1, "can't add %s to bridge %s", if_name, br_name);
}
/*
* This sets up the Host end of the network device with an IP address, brings
* it up so packets will flow, the copies the MAC address into the hwaddr
* pointer.
*/
static void configure_device(int fd, const char *tapif, u32 ipaddr)
{
struct ifreq ifr;
struct sockaddr_in sin;
memset(&ifr, 0, sizeof(ifr));
strcpy(ifr.ifr_name, tapif);
/* Don't read these incantations. Just cut & paste them like I did! */
sin.sin_family = AF_INET;
sin.sin_addr.s_addr = htonl(ipaddr);
memcpy(&ifr.ifr_addr, &sin, sizeof(sin));
if (ioctl(fd, SIOCSIFADDR, &ifr) != 0)
err(1, "Setting %s interface address", tapif);
ifr.ifr_flags = IFF_UP;
if (ioctl(fd, SIOCSIFFLAGS, &ifr) != 0)
err(1, "Bringing interface %s up", tapif);
}
static int get_tun_device(char tapif[IFNAMSIZ])
{
struct ifreq ifr;
int vnet_hdr_sz;
int netfd;
/* Start with this zeroed. Messy but sure. */
memset(&ifr, 0, sizeof(ifr));
/*
* We open the /dev/net/tun device and tell it we want a tap device. A
* tap device is like a tun device, only somehow different. To tell
* the truth, I completely blundered my way through this code, but it
* works now!
*/
netfd = open_or_die("/dev/net/tun", O_RDWR);
ifr.ifr_flags = IFF_TAP | IFF_NO_PI | IFF_VNET_HDR;
strcpy(ifr.ifr_name, "tap%d");
if (ioctl(netfd, TUNSETIFF, &ifr) != 0)
err(1, "configuring /dev/net/tun");
if (ioctl(netfd, TUNSETOFFLOAD,
TUN_F_CSUM|TUN_F_TSO4|TUN_F_TSO6|TUN_F_TSO_ECN) != 0)
err(1, "Could not set features for tun device");
/*
* We don't need checksums calculated for packets coming in this
* device: trust us!
*/
ioctl(netfd, TUNSETNOCSUM, 1);
/*
* In virtio before 1.0 (aka legacy virtio), we added a 16-bit
* field at the end of the network header iff
* VIRTIO_NET_F_MRG_RXBUF was negotiated. For virtio 1.0,
* that became the norm, but we need to tell the tun device
* about our expanded header (which is called
* virtio_net_hdr_mrg_rxbuf in the legacy system).
*/
vnet_hdr_sz = sizeof(struct virtio_net_hdr_v1);
if (ioctl(netfd, TUNSETVNETHDRSZ, &vnet_hdr_sz) != 0)
err(1, "Setting tun header size to %u", vnet_hdr_sz);
memcpy(tapif, ifr.ifr_name, IFNAMSIZ);
return netfd;
}
/*L:195
* Our network is a Host<->Guest network. This can either use bridging or
* routing, but the principle is the same: it uses the "tun" device to inject
* packets into the Host as if they came in from a normal network card. We
* just shunt packets between the Guest and the tun device.
*/
static void setup_tun_net(char *arg)
{
struct device *dev;
struct net_info *net_info = malloc(sizeof(*net_info));
int ipfd;
u32 ip = INADDR_ANY;
bool bridging = false;
char tapif[IFNAMSIZ], *p;
struct virtio_net_config conf;
net_info->tunfd = get_tun_device(tapif);
/* First we create a new network device. */
dev = new_pci_device("net", VIRTIO_ID_NET, 0x02, 0x00);
dev->priv = net_info;
/* Network devices need a recv and a send queue, just like console. */
add_pci_virtqueue(dev, net_input, "rx");
add_pci_virtqueue(dev, net_output, "tx");
/*
* We need a socket to perform the magic network ioctls to bring up the
* tap interface, connect to the bridge etc. Any socket will do!
*/
ipfd = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP);
if (ipfd < 0)
err(1, "opening IP socket");
/* If the command line was --tunnet=bridge:<name> do bridging. */
if (!strncmp(BRIDGE_PFX, arg, strlen(BRIDGE_PFX))) {
arg += strlen(BRIDGE_PFX);
bridging = true;
}
/* A mac address may follow the bridge name or IP address */
p = strchr(arg, ':');
if (p) {
str2mac(p+1, conf.mac);
add_pci_feature(dev, VIRTIO_NET_F_MAC);
*p = '\0';
}
/* arg is now either an IP address or a bridge name */
if (bridging)
add_to_bridge(ipfd, tapif, arg);
else
ip = str2ip(arg);
/* Set up the tun device. */
configure_device(ipfd, tapif, ip);
/* Expect Guest to handle everything except UFO */
add_pci_feature(dev, VIRTIO_NET_F_CSUM);
add_pci_feature(dev, VIRTIO_NET_F_GUEST_CSUM);
add_pci_feature(dev, VIRTIO_NET_F_GUEST_TSO4);
add_pci_feature(dev, VIRTIO_NET_F_GUEST_TSO6);
add_pci_feature(dev, VIRTIO_NET_F_GUEST_ECN);
add_pci_feature(dev, VIRTIO_NET_F_HOST_TSO4);
add_pci_feature(dev, VIRTIO_NET_F_HOST_TSO6);
add_pci_feature(dev, VIRTIO_NET_F_HOST_ECN);
/* We handle indirect ring entries */
add_pci_feature(dev, VIRTIO_RING_F_INDIRECT_DESC);
set_device_config(dev, &conf, sizeof(conf));
/* We don't need the socket any more; setup is done. */
close(ipfd);
if (bridging)
verbose("device %u: tun %s attached to bridge: %s\n",
devices.device_num, tapif, arg);
else
verbose("device %u: tun %s: %s\n",
devices.device_num, tapif, arg);
}
/*:*/
/* This hangs off device->priv. */
struct vblk_info {
/* The size of the file. */
off64_t len;
/* The file descriptor for the file. */
int fd;
};
/*L:210
* The Disk
*
* The disk only has one virtqueue, so it only has one thread. It is really
* simple: the Guest asks for a block number and we read or write that position
* in the file.
*
* Before we serviced each virtqueue in a separate thread, that was unacceptably
* slow: the Guest waits until the read is finished before running anything
* else, even if it could have been doing useful work.
*
* We could have used async I/O, except it's reputed to suck so hard that
* characters actually go missing from your code when you try to use it.
*/
static void blk_request(struct virtqueue *vq)
{
struct vblk_info *vblk = vq->dev->priv;
unsigned int head, out_num, in_num, wlen;
int ret, i;
u8 *in;
struct virtio_blk_outhdr out;
struct iovec iov[vq->vring.num];
off64_t off;
/*
* Get the next request, where we normally wait. It triggers the
* interrupt to acknowledge previously serviced requests (if any).
*/
head = wait_for_vq_desc(vq, iov, &out_num, &in_num);
/* Copy the output header from the front of the iov (adjusts iov) */
iov_consume(vq->dev, iov, out_num, &out, sizeof(out));
/* Find and trim end of iov input array, for our status byte. */
in = NULL;
for (i = out_num + in_num - 1; i >= out_num; i--) {
if (iov[i].iov_len > 0) {
in = iov[i].iov_base + iov[i].iov_len - 1;
iov[i].iov_len--;
break;
}
}
if (!in)
bad_driver_vq(vq, "Bad virtblk cmd with no room for status");
/*
* For historical reasons, block operations are expressed in 512 byte
* "sectors".
*/
off = out.sector * 512;
if (out.type & VIRTIO_BLK_T_OUT) {
/*
* Write
*
* Move to the right location in the block file. This can fail
* if they try to write past end.
*/
if (lseek64(vblk->fd, off, SEEK_SET) != off)
err(1, "Bad seek to sector %llu", out.sector);
ret = writev(vblk->fd, iov, out_num);
verbose("WRITE to sector %llu: %i\n", out.sector, ret);
/*
* Grr... Now we know how long the descriptor they sent was, we
* make sure they didn't try to write over the end of the block
* file (possibly extending it).
*/
if (ret > 0 && off + ret > vblk->len) {
/* Trim it back to the correct length */
ftruncate64(vblk->fd, vblk->len);
/* Die, bad Guest, die. */
bad_driver_vq(vq, "Write past end %llu+%u", off, ret);
}
wlen = sizeof(*in);
*in = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR);
} else if (out.type & VIRTIO_BLK_T_FLUSH) {
/* Flush */
ret = fdatasync(vblk->fd);
verbose("FLUSH fdatasync: %i\n", ret);
wlen = sizeof(*in);
*in = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR);
} else {
/*
* Read
*
* Move to the right location in the block file. This can fail
* if they try to read past end.
*/
if (lseek64(vblk->fd, off, SEEK_SET) != off)
err(1, "Bad seek to sector %llu", out.sector);
ret = readv(vblk->fd, iov + out_num, in_num);
if (ret >= 0) {
wlen = sizeof(*in) + ret;
*in = VIRTIO_BLK_S_OK;
} else {
wlen = sizeof(*in);
*in = VIRTIO_BLK_S_IOERR;
}
}
/* Finished that request. */
add_used(vq, head, wlen);
}
/*L:198 This actually sets up a virtual block device. */
static void setup_block_file(const char *filename)
{
struct device *dev;
struct vblk_info *vblk;
struct virtio_blk_config conf;
/* Create the device. */
dev = new_pci_device("block", VIRTIO_ID_BLOCK, 0x01, 0x80);
/* The device has one virtqueue, where the Guest places requests. */
add_pci_virtqueue(dev, blk_request, "request");
/* Allocate the room for our own bookkeeping */
vblk = dev->priv = malloc(sizeof(*vblk));
/* First we open the file and store the length. */
vblk->fd = open_or_die(filename, O_RDWR|O_LARGEFILE);
vblk->len = lseek64(vblk->fd, 0, SEEK_END);
/* Tell Guest how many sectors this device has. */
conf.capacity = cpu_to_le64(vblk->len / 512);
/*
* Tell Guest not to put in too many descriptors at once: two are used
* for the in and out elements.
*/
add_pci_feature(dev, VIRTIO_BLK_F_SEG_MAX);
conf.seg_max = cpu_to_le32(VIRTQUEUE_NUM - 2);
set_device_config(dev, &conf, sizeof(struct virtio_blk_config));
verbose("device %u: virtblock %llu sectors\n",
devices.device_num, le64_to_cpu(conf.capacity));
}
/*L:211
* Our random number generator device reads from /dev/urandom into the Guest's
* input buffers. The usual case is that the Guest doesn't want random numbers
* and so has no buffers although /dev/urandom is still readable, whereas
* console is the reverse.
*
* The same logic applies, however.
*/
struct rng_info {
int rfd;
};
static void rng_input(struct virtqueue *vq)
{
int len;
unsigned int head, in_num, out_num, totlen = 0;
struct rng_info *rng_info = vq->dev->priv;
struct iovec iov[vq->vring.num];
/* First we need a buffer from the Guests's virtqueue. */
head = wait_for_vq_desc(vq, iov, &out_num, &in_num);
if (out_num)
bad_driver_vq(vq, "Output buffers in rng?");
/*
* Just like the console write, we loop to cover the whole iovec.
* In this case, short reads actually happen quite a bit.
*/
while (!iov_empty(iov, in_num)) {
len = readv(rng_info->rfd, iov, in_num);
if (len <= 0)
err(1, "Read from /dev/urandom gave %i", len);
iov_consume(vq->dev, iov, in_num, NULL, len);
totlen += len;
}
/* Tell the Guest about the new input. */
add_used(vq, head, totlen);
}
/*L:199
* This creates a "hardware" random number device for the Guest.
*/
static void setup_rng(void)
{
struct device *dev;
struct rng_info *rng_info = malloc(sizeof(*rng_info));
/* Our device's private info simply contains the /dev/urandom fd. */
rng_info->rfd = open_or_die("/dev/urandom", O_RDONLY);
/* Create the new device. */
dev = new_pci_device("rng", VIRTIO_ID_RNG, 0xff, 0);
dev->priv = rng_info;
/* The device has one virtqueue, where the Guest places inbufs. */
add_pci_virtqueue(dev, rng_input, "input");
/* We don't have any configuration space */
no_device_config(dev);
verbose("device %u: rng\n", devices.device_num);
}
/* That's the end of device setup. */
/*L:230 Reboot is pretty easy: clean up and exec() the Launcher afresh. */
static void __attribute__((noreturn)) restart_guest(void)
{
unsigned int i;
/*
* Since we don't track all open fds, we simply close everything beyond
* stderr.
*/
for (i = 3; i < FD_SETSIZE; i++)
close(i);
/* Reset all the devices (kills all threads). */
cleanup_devices();
execv(main_args[0], main_args);
err(1, "Could not exec %s", main_args[0]);
}
/*L:220
* Finally we reach the core of the Launcher which runs the Guest, serves
* its input and output, and finally, lays it to rest.
*/
static void __attribute__((noreturn)) run_guest(void)
{
for (;;) {
struct lguest_pending notify;
int readval;
/* We read from the /dev/lguest device to run the Guest. */
readval = pread(lguest_fd, ¬ify, sizeof(notify), cpu_id);
if (readval == sizeof(notify)) {
if (notify.trap == 13) {
verbose("Emulating instruction at %#x\n",
getreg(eip));
emulate_insn(notify.insn);
} else if (notify.trap == 14) {
verbose("Emulating MMIO at %#x\n",
getreg(eip));
emulate_mmio(notify.addr, notify.insn);
} else
errx(1, "Unknown trap %i addr %#08x\n",
notify.trap, notify.addr);
/* ENOENT means the Guest died. Reading tells us why. */
} else if (errno == ENOENT) {
char reason[1024] = { 0 };
pread(lguest_fd, reason, sizeof(reason)-1, cpu_id);
errx(1, "%s", reason);
/* ERESTART means that we need to reboot the guest */
} else if (errno == ERESTART) {
restart_guest();
/* Anything else means a bug or incompatible change. */
} else
err(1, "Running guest failed");
}
}
/*L:240
* This is the end of the Launcher. The good news: we are over halfway
* through! The bad news: the most fiendish part of the code still lies ahead
* of us.
*
* Are you ready? Take a deep breath and join me in the core of the Host, in
* "make Host".
:*/
static struct option opts[] = {
{ "verbose", 0, NULL, 'v' },
{ "tunnet", 1, NULL, 't' },
{ "block", 1, NULL, 'b' },
{ "rng", 0, NULL, 'r' },
{ "initrd", 1, NULL, 'i' },
{ "username", 1, NULL, 'u' },
{ "chroot", 1, NULL, 'c' },
{ NULL },
};
static void usage(void)
{
errx(1, "Usage: lguest [--verbose] "
"[--tunnet=(<ipaddr>:<macaddr>|bridge:<bridgename>:<macaddr>)\n"
"|--block=<filename>|--initrd=<filename>]...\n"
"<mem-in-mb> vmlinux [args...]");
}
/*L:105 The main routine is where the real work begins: */
int main(int argc, char *argv[])
{
/* Memory, code startpoint and size of the (optional) initrd. */
unsigned long mem = 0, start, initrd_size = 0;
/* Two temporaries. */
int i, c;
/* The boot information for the Guest. */
struct boot_params *boot;
/* If they specify an initrd file to load. */
const char *initrd_name = NULL;
/* Password structure for initgroups/setres[gu]id */
struct passwd *user_details = NULL;
/* Directory to chroot to */
char *chroot_path = NULL;
/* Save the args: we "reboot" by execing ourselves again. */
main_args = argv;
/*
* First we initialize the device list. We remember next interrupt
* number to use for devices (1: remember that 0 is used by the timer).
*/
devices.next_irq = 1;
/* We're CPU 0. In fact, that's the only CPU possible right now. */
cpu_id = 0;
/*
* We need to know how much memory so we can set up the device
* descriptor and memory pages for the devices as we parse the command
* line. So we quickly look through the arguments to find the amount
* of memory now.
*/
for (i = 1; i < argc; i++) {
if (argv[i][0] != '-') {
mem = atoi(argv[i]) * 1024 * 1024;
/*
* We start by mapping anonymous pages over all of
* guest-physical memory range. This fills it with 0,
* and ensures that the Guest won't be killed when it
* tries to access it.
*/
guest_base = map_zeroed_pages(mem / getpagesize()
+ DEVICE_PAGES);
guest_limit = mem;
guest_max = guest_mmio = mem + DEVICE_PAGES*getpagesize();
break;
}
}
/* If we exit via err(), this kills all the threads, restores tty. */
atexit(cleanup_devices);
/* We always have a console device, and it's always device 1. */
setup_console();
/* The options are fairly straight-forward */
while ((c = getopt_long(argc, argv, "v", opts, NULL)) != EOF) {
switch (c) {
case 'v':
verbose = true;
break;
case 't':
setup_tun_net(optarg);
break;
case 'b':
setup_block_file(optarg);
break;
case 'r':
setup_rng();
break;
case 'i':
initrd_name = optarg;
break;
case 'u':
user_details = getpwnam(optarg);
if (!user_details)
err(1, "getpwnam failed, incorrect username?");
break;
case 'c':
chroot_path = optarg;
break;
default:
warnx("Unknown argument %s", argv[optind]);
usage();
}
}
/*
* After the other arguments we expect memory and kernel image name,
* followed by command line arguments for the kernel.
*/
if (optind + 2 > argc)
usage();
verbose("Guest base is at %p\n", guest_base);
/* Initialize the (fake) PCI host bridge device. */
init_pci_host_bridge();
/* Now we load the kernel */
start = load_kernel(open_or_die(argv[optind+1], O_RDONLY));
/* Boot information is stashed at physical address 0 */
boot = from_guest_phys(0);
/* Map the initrd image if requested (at top of physical memory) */
if (initrd_name) {
initrd_size = load_initrd(initrd_name, mem);
/*
* These are the location in the Linux boot header where the
* start and size of the initrd are expected to be found.
*/
boot->hdr.ramdisk_image = mem - initrd_size;
boot->hdr.ramdisk_size = initrd_size;
/* The bootloader type 0xFF means "unknown"; that's OK. */
boot->hdr.type_of_loader = 0xFF;
}
/*
* The Linux boot header contains an "E820" memory map: ours is a
* simple, single region.
*/
boot->e820_entries = 1;
boot->e820_map[0] = ((struct e820entry) { 0, mem, E820_RAM });
/*
* The boot header contains a command line pointer: we put the command
* line after the boot header.
*/
boot->hdr.cmd_line_ptr = to_guest_phys(boot + 1);
/* We use a simple helper to copy the arguments separated by spaces. */
concat((char *)(boot + 1), argv+optind+2);
/* Set kernel alignment to 16M (CONFIG_PHYSICAL_ALIGN) */
boot->hdr.kernel_alignment = 0x1000000;
/* Boot protocol version: 2.07 supports the fields for lguest. */
boot->hdr.version = 0x207;
/* X86_SUBARCH_LGUEST tells the Guest it's an lguest. */
boot->hdr.hardware_subarch = X86_SUBARCH_LGUEST;
/* Tell the entry path not to try to reload segment registers. */
boot->hdr.loadflags |= KEEP_SEGMENTS;
/* We don't support tboot: */
boot->tboot_addr = 0;
/* Ensure this is 0 to prevent APM from loading: */
boot->apm_bios_info.version = 0;
/* We tell the kernel to initialize the Guest. */
tell_kernel(start);
/* Ensure that we terminate if a device-servicing child dies. */
signal(SIGCHLD, kill_launcher);
/* If requested, chroot to a directory */
if (chroot_path) {
if (chroot(chroot_path) != 0)
err(1, "chroot(\"%s\") failed", chroot_path);
if (chdir("/") != 0)
err(1, "chdir(\"/\") failed");
verbose("chroot done\n");
}
/* If requested, drop privileges */
if (user_details) {
uid_t u;
gid_t g;
u = user_details->pw_uid;
g = user_details->pw_gid;
if (initgroups(user_details->pw_name, g) != 0)
err(1, "initgroups failed");
if (setresgid(g, g, g) != 0)
err(1, "setresgid failed");
if (setresuid(u, u, u) != 0)
err(1, "setresuid failed");
verbose("Dropping privileges completed\n");
}
/* Finally, run the Guest. This doesn't return. */
run_guest();
}
/*:*/
/*M:999
* Mastery is done: you now know everything I do.
*
* But surely you have seen code, features and bugs in your wanderings which
* you now yearn to attack? That is the real game, and I look forward to you
* patching and forking lguest into the Your-Name-Here-visor.
*
* Farewell, and good coding!
* Rusty Russell.
*/
