hv.c
// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (c) 2009, Microsoft Corporation.
*
* Authors:
* Haiyang Zhang <haiyangz@microsoft.com>
* Hank Janssen <hjanssen@microsoft.com>
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/hyperv.h>
#include <linux/random.h>
#include <linux/clockchips.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <clocksource/hyperv_timer.h>
#include <asm/mshyperv.h>
#include "hyperv_vmbus.h"
/* The one and only */
struct hv_context hv_context;
/*
* hv_init - Main initialization routine.
*
* This routine must be called before any other routines in here are called
*/
int hv_init(void)
{
hv_context.cpu_context = alloc_percpu(struct hv_per_cpu_context);
if (!hv_context.cpu_context)
return -ENOMEM;
return 0;
}
/*
* Functions for allocating and freeing memory with size and
* alignment HV_HYP_PAGE_SIZE. These functions are needed because
* the guest page size may not be the same as the Hyper-V page
* size. We depend upon kmalloc() aligning power-of-two size
* allocations to the allocation size boundary, so that the
* allocated memory appears to Hyper-V as a page of the size
* it expects.
*/
void *hv_alloc_hyperv_page(void)
{
BUILD_BUG_ON(PAGE_SIZE < HV_HYP_PAGE_SIZE);
if (PAGE_SIZE == HV_HYP_PAGE_SIZE)
return (void *)__get_free_page(GFP_KERNEL);
else
return kmalloc(HV_HYP_PAGE_SIZE, GFP_KERNEL);
}
void *hv_alloc_hyperv_zeroed_page(void)
{
if (PAGE_SIZE == HV_HYP_PAGE_SIZE)
return (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
else
return kzalloc(HV_HYP_PAGE_SIZE, GFP_KERNEL);
}
void hv_free_hyperv_page(unsigned long addr)
{
if (PAGE_SIZE == HV_HYP_PAGE_SIZE)
free_page(addr);
else
kfree((void *)addr);
}
/*
* hv_post_message - Post a message using the hypervisor message IPC.
*
* This involves a hypercall.
*/
int hv_post_message(union hv_connection_id connection_id,
enum hv_message_type message_type,
void *payload, size_t payload_size)
{
struct hv_input_post_message *aligned_msg;
struct hv_per_cpu_context *hv_cpu;
u64 status;
if (payload_size > HV_MESSAGE_PAYLOAD_BYTE_COUNT)
return -EMSGSIZE;
hv_cpu = get_cpu_ptr(hv_context.cpu_context);
aligned_msg = hv_cpu->post_msg_page;
aligned_msg->connectionid = connection_id;
aligned_msg->reserved = 0;
aligned_msg->message_type = message_type;
aligned_msg->payload_size = payload_size;
memcpy((void *)aligned_msg->payload, payload, payload_size);
status = hv_do_hypercall(HVCALL_POST_MESSAGE, aligned_msg, NULL);
/* Preemption must remain disabled until after the hypercall
* so some other thread can't get scheduled onto this cpu and
* corrupt the per-cpu post_msg_page
*/
put_cpu_ptr(hv_cpu);
return hv_result(status);
}
int hv_synic_alloc(void)
{
int cpu;
struct hv_per_cpu_context *hv_cpu;
/*
* First, zero all per-cpu memory areas so hv_synic_free() can
* detect what memory has been allocated and cleanup properly
* after any failures.
*/
for_each_present_cpu(cpu) {
hv_cpu = per_cpu_ptr(hv_context.cpu_context, cpu);
memset(hv_cpu, 0, sizeof(*hv_cpu));
}
hv_context.hv_numa_map = kcalloc(nr_node_ids, sizeof(struct cpumask),
GFP_KERNEL);
if (hv_context.hv_numa_map == NULL) {
pr_err("Unable to allocate NUMA map\n");
goto err;
}
for_each_present_cpu(cpu) {
hv_cpu = per_cpu_ptr(hv_context.cpu_context, cpu);
tasklet_init(&hv_cpu->msg_dpc,
vmbus_on_msg_dpc, (unsigned long) hv_cpu);
hv_cpu->synic_message_page =
(void *)get_zeroed_page(GFP_ATOMIC);
if (hv_cpu->synic_message_page == NULL) {
pr_err("Unable to allocate SYNIC message page\n");
goto err;
}
hv_cpu->synic_event_page = (void *)get_zeroed_page(GFP_ATOMIC);
if (hv_cpu->synic_event_page == NULL) {
pr_err("Unable to allocate SYNIC event page\n");
goto err;
}
hv_cpu->post_msg_page = (void *)get_zeroed_page(GFP_ATOMIC);
if (hv_cpu->post_msg_page == NULL) {
pr_err("Unable to allocate post msg page\n");
goto err;
}
}
return 0;
err:
/*
* Any memory allocations that succeeded will be freed when
* the caller cleans up by calling hv_synic_free()
*/
return -ENOMEM;
}
void hv_synic_free(void)
{
int cpu;
for_each_present_cpu(cpu) {
struct hv_per_cpu_context *hv_cpu
= per_cpu_ptr(hv_context.cpu_context, cpu);
free_page((unsigned long)hv_cpu->synic_event_page);
free_page((unsigned long)hv_cpu->synic_message_page);
free_page((unsigned long)hv_cpu->post_msg_page);
}
kfree(hv_context.hv_numa_map);
}
/*
* hv_synic_init - Initialize the Synthetic Interrupt Controller.
*
* If it is already initialized by another entity (ie x2v shim), we need to
* retrieve the initialized message and event pages. Otherwise, we create and
* initialize the message and event pages.
*/
void hv_synic_enable_regs(unsigned int cpu)
{
struct hv_per_cpu_context *hv_cpu
= per_cpu_ptr(hv_context.cpu_context, cpu);
union hv_synic_simp simp;
union hv_synic_siefp siefp;
union hv_synic_sint shared_sint;
union hv_synic_scontrol sctrl;
/* Setup the Synic's message page */
simp.as_uint64 = hv_get_register(HV_REGISTER_SIMP);
simp.simp_enabled = 1;
simp.base_simp_gpa = virt_to_phys(hv_cpu->synic_message_page)
>> HV_HYP_PAGE_SHIFT;
hv_set_register(HV_REGISTER_SIMP, simp.as_uint64);
/* Setup the Synic's event page */
siefp.as_uint64 = hv_get_register(HV_REGISTER_SIEFP);
siefp.siefp_enabled = 1;
siefp.base_siefp_gpa = virt_to_phys(hv_cpu->synic_event_page)
>> HV_HYP_PAGE_SHIFT;
hv_set_register(HV_REGISTER_SIEFP, siefp.as_uint64);
/* Setup the shared SINT. */
if (vmbus_irq != -1)
enable_percpu_irq(vmbus_irq, 0);
shared_sint.as_uint64 = hv_get_register(HV_REGISTER_SINT0 +
VMBUS_MESSAGE_SINT);
shared_sint.vector = vmbus_interrupt;
shared_sint.masked = false;
/*
* On architectures where Hyper-V doesn't support AEOI (e.g., ARM64),
* it doesn't provide a recommendation flag and AEOI must be disabled.
*/
#ifdef HV_DEPRECATING_AEOI_RECOMMENDED
shared_sint.auto_eoi =
!(ms_hyperv.hints & HV_DEPRECATING_AEOI_RECOMMENDED);
#else
shared_sint.auto_eoi = 0;
#endif
hv_set_register(HV_REGISTER_SINT0 + VMBUS_MESSAGE_SINT,
shared_sint.as_uint64);
/* Enable the global synic bit */
sctrl.as_uint64 = hv_get_register(HV_REGISTER_SCONTROL);
sctrl.enable = 1;
hv_set_register(HV_REGISTER_SCONTROL, sctrl.as_uint64);
}
int hv_synic_init(unsigned int cpu)
{
hv_synic_enable_regs(cpu);
hv_stimer_legacy_init(cpu, VMBUS_MESSAGE_SINT);
return 0;
}
/*
* hv_synic_cleanup - Cleanup routine for hv_synic_init().
*/
void hv_synic_disable_regs(unsigned int cpu)
{
union hv_synic_sint shared_sint;
union hv_synic_simp simp;
union hv_synic_siefp siefp;
union hv_synic_scontrol sctrl;
shared_sint.as_uint64 = hv_get_register(HV_REGISTER_SINT0 +
VMBUS_MESSAGE_SINT);
shared_sint.masked = 1;
/* Need to correctly cleanup in the case of SMP!!! */
/* Disable the interrupt */
hv_set_register(HV_REGISTER_SINT0 + VMBUS_MESSAGE_SINT,
shared_sint.as_uint64);
simp.as_uint64 = hv_get_register(HV_REGISTER_SIMP);
simp.simp_enabled = 0;
simp.base_simp_gpa = 0;
hv_set_register(HV_REGISTER_SIMP, simp.as_uint64);
siefp.as_uint64 = hv_get_register(HV_REGISTER_SIEFP);
siefp.siefp_enabled = 0;
siefp.base_siefp_gpa = 0;
hv_set_register(HV_REGISTER_SIEFP, siefp.as_uint64);
/* Disable the global synic bit */
sctrl.as_uint64 = hv_get_register(HV_REGISTER_SCONTROL);
sctrl.enable = 0;
hv_set_register(HV_REGISTER_SCONTROL, sctrl.as_uint64);
if (vmbus_irq != -1)
disable_percpu_irq(vmbus_irq);
}
#define HV_MAX_TRIES 3
/*
* Scan the event flags page of 'this' CPU looking for any bit that is set. If we find one
* bit set, then wait for a few milliseconds. Repeat these steps for a maximum of 3 times.
* Return 'true', if there is still any set bit after this operation; 'false', otherwise.
*
* If a bit is set, that means there is a pending channel interrupt. The expectation is
* that the normal interrupt handling mechanism will find and process the channel interrupt
* "very soon", and in the process clear the bit.
*/
static bool hv_synic_event_pending(void)
{
struct hv_per_cpu_context *hv_cpu = this_cpu_ptr(hv_context.cpu_context);
union hv_synic_event_flags *event =
(union hv_synic_event_flags *)hv_cpu->synic_event_page + VMBUS_MESSAGE_SINT;
unsigned long *recv_int_page = event->flags; /* assumes VMBus version >= VERSION_WIN8 */
bool pending;
u32 relid;
int tries = 0;
retry:
pending = false;
for_each_set_bit(relid, recv_int_page, HV_EVENT_FLAGS_COUNT) {
/* Special case - VMBus channel protocol messages */
if (relid == 0)
continue;
pending = true;
break;
}
if (pending && tries++ < HV_MAX_TRIES) {
usleep_range(10000, 20000);
goto retry;
}
return pending;
}
int hv_synic_cleanup(unsigned int cpu)
{
struct vmbus_channel *channel, *sc;
bool channel_found = false;
if (vmbus_connection.conn_state != CONNECTED)
goto always_cleanup;
/*
* Hyper-V does not provide a way to change the connect CPU once
* it is set; we must prevent the connect CPU from going offline
* while the VM is running normally. But in the panic or kexec()
* path where the vmbus is already disconnected, the CPU must be
* allowed to shut down.
*/
if (cpu == VMBUS_CONNECT_CPU)
return -EBUSY;
/*
* Search for channels which are bound to the CPU we're about to
* cleanup. In case we find one and vmbus is still connected, we
* fail; this will effectively prevent CPU offlining.
*
* TODO: Re-bind the channels to different CPUs.
*/
mutex_lock(&vmbus_connection.channel_mutex);
list_for_each_entry(channel, &vmbus_connection.chn_list, listentry) {
if (channel->target_cpu == cpu) {
channel_found = true;
break;
}
list_for_each_entry(sc, &channel->sc_list, sc_list) {
if (sc->target_cpu == cpu) {
channel_found = true;
break;
}
}
if (channel_found)
break;
}
mutex_unlock(&vmbus_connection.channel_mutex);
if (channel_found)
return -EBUSY;
/*
* channel_found == false means that any channels that were previously
* assigned to the CPU have been reassigned elsewhere with a call of
* vmbus_send_modifychannel(). Scan the event flags page looking for
* bits that are set and waiting with a timeout for vmbus_chan_sched()
* to process such bits. If bits are still set after this operation
* and VMBus is connected, fail the CPU offlining operation.
*/
if (vmbus_proto_version >= VERSION_WIN10_V4_1 && hv_synic_event_pending())
return -EBUSY;
always_cleanup:
hv_stimer_legacy_cleanup(cpu);
hv_synic_disable_regs(cpu);
return 0;
}