https://github.com/torvalds/linux
Tip revision: f443e374ae131c168a065ea1748feac6b2e76613 authored by Linus Torvalds on 20 March 2022, 20:14:17 UTC
Linux 5.17
Linux 5.17
Tip revision: f443e37
hv_init.c
// SPDX-License-Identifier: GPL-2.0-only
/*
* X86 specific Hyper-V initialization code.
*
* Copyright (C) 2016, Microsoft, Inc.
*
* Author : K. Y. Srinivasan <kys@microsoft.com>
*/
#include <linux/efi.h>
#include <linux/types.h>
#include <linux/bitfield.h>
#include <linux/io.h>
#include <asm/apic.h>
#include <asm/desc.h>
#include <asm/hypervisor.h>
#include <asm/hyperv-tlfs.h>
#include <asm/mshyperv.h>
#include <asm/idtentry.h>
#include <linux/kexec.h>
#include <linux/version.h>
#include <linux/vmalloc.h>
#include <linux/mm.h>
#include <linux/hyperv.h>
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/cpuhotplug.h>
#include <linux/syscore_ops.h>
#include <clocksource/hyperv_timer.h>
#include <linux/highmem.h>
#include <linux/swiotlb.h>
int hyperv_init_cpuhp;
u64 hv_current_partition_id = ~0ull;
EXPORT_SYMBOL_GPL(hv_current_partition_id);
void *hv_hypercall_pg;
EXPORT_SYMBOL_GPL(hv_hypercall_pg);
union hv_ghcb * __percpu *hv_ghcb_pg;
/* Storage to save the hypercall page temporarily for hibernation */
static void *hv_hypercall_pg_saved;
struct hv_vp_assist_page **hv_vp_assist_page;
EXPORT_SYMBOL_GPL(hv_vp_assist_page);
static int hyperv_init_ghcb(void)
{
u64 ghcb_gpa;
void *ghcb_va;
void **ghcb_base;
if (!hv_isolation_type_snp())
return 0;
if (!hv_ghcb_pg)
return -EINVAL;
/*
* GHCB page is allocated by paravisor. The address
* returned by MSR_AMD64_SEV_ES_GHCB is above shared
* memory boundary and map it here.
*/
rdmsrl(MSR_AMD64_SEV_ES_GHCB, ghcb_gpa);
ghcb_va = memremap(ghcb_gpa, HV_HYP_PAGE_SIZE, MEMREMAP_WB);
if (!ghcb_va)
return -ENOMEM;
ghcb_base = (void **)this_cpu_ptr(hv_ghcb_pg);
*ghcb_base = ghcb_va;
return 0;
}
static int hv_cpu_init(unsigned int cpu)
{
union hv_vp_assist_msr_contents msr = { 0 };
struct hv_vp_assist_page **hvp = &hv_vp_assist_page[smp_processor_id()];
int ret;
ret = hv_common_cpu_init(cpu);
if (ret)
return ret;
if (!hv_vp_assist_page)
return 0;
if (!*hvp) {
if (hv_root_partition) {
/*
* For root partition we get the hypervisor provided VP assist
* page, instead of allocating a new page.
*/
rdmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
*hvp = memremap(msr.pfn <<
HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT,
PAGE_SIZE, MEMREMAP_WB);
} else {
/*
* The VP assist page is an "overlay" page (see Hyper-V TLFS's
* Section 5.2.1 "GPA Overlay Pages"). Here it must be zeroed
* out to make sure we always write the EOI MSR in
* hv_apic_eoi_write() *after* the EOI optimization is disabled
* in hv_cpu_die(), otherwise a CPU may not be stopped in the
* case of CPU offlining and the VM will hang.
*/
*hvp = __vmalloc(PAGE_SIZE, GFP_KERNEL | __GFP_ZERO);
if (*hvp)
msr.pfn = vmalloc_to_pfn(*hvp);
}
WARN_ON(!(*hvp));
if (*hvp) {
msr.enable = 1;
wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
}
}
return hyperv_init_ghcb();
}
static void (*hv_reenlightenment_cb)(void);
static void hv_reenlightenment_notify(struct work_struct *dummy)
{
struct hv_tsc_emulation_status emu_status;
rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
/* Don't issue the callback if TSC accesses are not emulated */
if (hv_reenlightenment_cb && emu_status.inprogress)
hv_reenlightenment_cb();
}
static DECLARE_DELAYED_WORK(hv_reenlightenment_work, hv_reenlightenment_notify);
void hyperv_stop_tsc_emulation(void)
{
u64 freq;
struct hv_tsc_emulation_status emu_status;
rdmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
emu_status.inprogress = 0;
wrmsrl(HV_X64_MSR_TSC_EMULATION_STATUS, *(u64 *)&emu_status);
rdmsrl(HV_X64_MSR_TSC_FREQUENCY, freq);
tsc_khz = div64_u64(freq, 1000);
}
EXPORT_SYMBOL_GPL(hyperv_stop_tsc_emulation);
static inline bool hv_reenlightenment_available(void)
{
/*
* Check for required features and privileges to make TSC frequency
* change notifications work.
*/
return ms_hyperv.features & HV_ACCESS_FREQUENCY_MSRS &&
ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE &&
ms_hyperv.features & HV_ACCESS_REENLIGHTENMENT;
}
DEFINE_IDTENTRY_SYSVEC(sysvec_hyperv_reenlightenment)
{
ack_APIC_irq();
inc_irq_stat(irq_hv_reenlightenment_count);
schedule_delayed_work(&hv_reenlightenment_work, HZ/10);
}
void set_hv_tscchange_cb(void (*cb)(void))
{
struct hv_reenlightenment_control re_ctrl = {
.vector = HYPERV_REENLIGHTENMENT_VECTOR,
.enabled = 1,
};
struct hv_tsc_emulation_control emu_ctrl = {.enabled = 1};
if (!hv_reenlightenment_available()) {
pr_warn("Hyper-V: reenlightenment support is unavailable\n");
return;
}
if (!hv_vp_index)
return;
hv_reenlightenment_cb = cb;
/* Make sure callback is registered before we write to MSRs */
wmb();
re_ctrl.target_vp = hv_vp_index[get_cpu()];
wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
wrmsrl(HV_X64_MSR_TSC_EMULATION_CONTROL, *((u64 *)&emu_ctrl));
put_cpu();
}
EXPORT_SYMBOL_GPL(set_hv_tscchange_cb);
void clear_hv_tscchange_cb(void)
{
struct hv_reenlightenment_control re_ctrl;
if (!hv_reenlightenment_available())
return;
rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
re_ctrl.enabled = 0;
wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *(u64 *)&re_ctrl);
hv_reenlightenment_cb = NULL;
}
EXPORT_SYMBOL_GPL(clear_hv_tscchange_cb);
static int hv_cpu_die(unsigned int cpu)
{
struct hv_reenlightenment_control re_ctrl;
unsigned int new_cpu;
void **ghcb_va;
if (hv_ghcb_pg) {
ghcb_va = (void **)this_cpu_ptr(hv_ghcb_pg);
if (*ghcb_va)
memunmap(*ghcb_va);
*ghcb_va = NULL;
}
hv_common_cpu_die(cpu);
if (hv_vp_assist_page && hv_vp_assist_page[cpu]) {
union hv_vp_assist_msr_contents msr = { 0 };
if (hv_root_partition) {
/*
* For root partition the VP assist page is mapped to
* hypervisor provided page, and thus we unmap the
* page here and nullify it, so that in future we have
* correct page address mapped in hv_cpu_init.
*/
memunmap(hv_vp_assist_page[cpu]);
hv_vp_assist_page[cpu] = NULL;
rdmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
msr.enable = 0;
}
wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, msr.as_uint64);
}
if (hv_reenlightenment_cb == NULL)
return 0;
rdmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
if (re_ctrl.target_vp == hv_vp_index[cpu]) {
/*
* Reassign reenlightenment notifications to some other online
* CPU or just disable the feature if there are no online CPUs
* left (happens on hibernation).
*/
new_cpu = cpumask_any_but(cpu_online_mask, cpu);
if (new_cpu < nr_cpu_ids)
re_ctrl.target_vp = hv_vp_index[new_cpu];
else
re_ctrl.enabled = 0;
wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
}
return 0;
}
static int __init hv_pci_init(void)
{
int gen2vm = efi_enabled(EFI_BOOT);
/*
* For Generation-2 VM, we exit from pci_arch_init() by returning 0.
* The purpose is to suppress the harmless warning:
* "PCI: Fatal: No config space access function found"
*/
if (gen2vm)
return 0;
/* For Generation-1 VM, we'll proceed in pci_arch_init(). */
return 1;
}
static int hv_suspend(void)
{
union hv_x64_msr_hypercall_contents hypercall_msr;
int ret;
if (hv_root_partition)
return -EPERM;
/*
* Reset the hypercall page as it is going to be invalidated
* across hibernation. Setting hv_hypercall_pg to NULL ensures
* that any subsequent hypercall operation fails safely instead of
* crashing due to an access of an invalid page. The hypercall page
* pointer is restored on resume.
*/
hv_hypercall_pg_saved = hv_hypercall_pg;
hv_hypercall_pg = NULL;
/* Disable the hypercall page in the hypervisor */
rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
hypercall_msr.enable = 0;
wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
ret = hv_cpu_die(0);
return ret;
}
static void hv_resume(void)
{
union hv_x64_msr_hypercall_contents hypercall_msr;
int ret;
ret = hv_cpu_init(0);
WARN_ON(ret);
/* Re-enable the hypercall page */
rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
hypercall_msr.enable = 1;
hypercall_msr.guest_physical_address =
vmalloc_to_pfn(hv_hypercall_pg_saved);
wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
hv_hypercall_pg = hv_hypercall_pg_saved;
hv_hypercall_pg_saved = NULL;
/*
* Reenlightenment notifications are disabled by hv_cpu_die(0),
* reenable them here if hv_reenlightenment_cb was previously set.
*/
if (hv_reenlightenment_cb)
set_hv_tscchange_cb(hv_reenlightenment_cb);
}
/* Note: when the ops are called, only CPU0 is online and IRQs are disabled. */
static struct syscore_ops hv_syscore_ops = {
.suspend = hv_suspend,
.resume = hv_resume,
};
static void (* __initdata old_setup_percpu_clockev)(void);
static void __init hv_stimer_setup_percpu_clockev(void)
{
/*
* Ignore any errors in setting up stimer clockevents
* as we can run with the LAPIC timer as a fallback.
*/
(void)hv_stimer_alloc(false);
/*
* Still register the LAPIC timer, because the direct-mode STIMER is
* not supported by old versions of Hyper-V. This also allows users
* to switch to LAPIC timer via /sys, if they want to.
*/
if (old_setup_percpu_clockev)
old_setup_percpu_clockev();
}
static void __init hv_get_partition_id(void)
{
struct hv_get_partition_id *output_page;
u64 status;
unsigned long flags;
local_irq_save(flags);
output_page = *this_cpu_ptr(hyperv_pcpu_output_arg);
status = hv_do_hypercall(HVCALL_GET_PARTITION_ID, NULL, output_page);
if (!hv_result_success(status)) {
/* No point in proceeding if this failed */
pr_err("Failed to get partition ID: %lld\n", status);
BUG();
}
hv_current_partition_id = output_page->partition_id;
local_irq_restore(flags);
}
/*
* This function is to be invoked early in the boot sequence after the
* hypervisor has been detected.
*
* 1. Setup the hypercall page.
* 2. Register Hyper-V specific clocksource.
* 3. Setup Hyper-V specific APIC entry points.
*/
void __init hyperv_init(void)
{
u64 guest_id;
union hv_x64_msr_hypercall_contents hypercall_msr;
int cpuhp;
if (x86_hyper_type != X86_HYPER_MS_HYPERV)
return;
if (hv_common_init())
return;
hv_vp_assist_page = kcalloc(num_possible_cpus(),
sizeof(*hv_vp_assist_page), GFP_KERNEL);
if (!hv_vp_assist_page) {
ms_hyperv.hints &= ~HV_X64_ENLIGHTENED_VMCS_RECOMMENDED;
goto common_free;
}
if (hv_isolation_type_snp()) {
hv_ghcb_pg = alloc_percpu(union hv_ghcb *);
if (!hv_ghcb_pg)
goto free_vp_assist_page;
}
cpuhp = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/hyperv_init:online",
hv_cpu_init, hv_cpu_die);
if (cpuhp < 0)
goto free_ghcb_page;
/*
* Setup the hypercall page and enable hypercalls.
* 1. Register the guest ID
* 2. Enable the hypercall and register the hypercall page
*/
guest_id = generate_guest_id(0, LINUX_VERSION_CODE, 0);
wrmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
/* Hyper-V requires to write guest os id via ghcb in SNP IVM. */
hv_ghcb_msr_write(HV_X64_MSR_GUEST_OS_ID, guest_id);
hv_hypercall_pg = __vmalloc_node_range(PAGE_SIZE, 1, VMALLOC_START,
VMALLOC_END, GFP_KERNEL, PAGE_KERNEL_ROX,
VM_FLUSH_RESET_PERMS, NUMA_NO_NODE,
__builtin_return_address(0));
if (hv_hypercall_pg == NULL)
goto clean_guest_os_id;
rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
hypercall_msr.enable = 1;
if (hv_root_partition) {
struct page *pg;
void *src, *dst;
/*
* For the root partition, the hypervisor will set up its
* hypercall page. The hypervisor guarantees it will not show
* up in the root's address space. The root can't change the
* location of the hypercall page.
*
* Order is important here. We must enable the hypercall page
* so it is populated with code, then copy the code to an
* executable page.
*/
wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
pg = vmalloc_to_page(hv_hypercall_pg);
dst = kmap(pg);
src = memremap(hypercall_msr.guest_physical_address << PAGE_SHIFT, PAGE_SIZE,
MEMREMAP_WB);
BUG_ON(!(src && dst));
memcpy(dst, src, HV_HYP_PAGE_SIZE);
memunmap(src);
kunmap(pg);
} else {
hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
}
/*
* hyperv_init() is called before LAPIC is initialized: see
* apic_intr_mode_init() -> x86_platform.apic_post_init() and
* apic_bsp_setup() -> setup_local_APIC(). The direct-mode STIMER
* depends on LAPIC, so hv_stimer_alloc() should be called from
* x86_init.timers.setup_percpu_clockev.
*/
old_setup_percpu_clockev = x86_init.timers.setup_percpu_clockev;
x86_init.timers.setup_percpu_clockev = hv_stimer_setup_percpu_clockev;
hv_apic_init();
x86_init.pci.arch_init = hv_pci_init;
register_syscore_ops(&hv_syscore_ops);
hyperv_init_cpuhp = cpuhp;
if (cpuid_ebx(HYPERV_CPUID_FEATURES) & HV_ACCESS_PARTITION_ID)
hv_get_partition_id();
BUG_ON(hv_root_partition && hv_current_partition_id == ~0ull);
#ifdef CONFIG_PCI_MSI
/*
* If we're running as root, we want to create our own PCI MSI domain.
* We can't set this in hv_pci_init because that would be too late.
*/
if (hv_root_partition)
x86_init.irqs.create_pci_msi_domain = hv_create_pci_msi_domain;
#endif
/* Query the VMs extended capability once, so that it can be cached. */
hv_query_ext_cap(0);
#ifdef CONFIG_SWIOTLB
/*
* Swiotlb bounce buffer needs to be mapped in extra address
* space. Map function doesn't work in the early place and so
* call swiotlb_update_mem_attributes() here.
*/
if (hv_is_isolation_supported())
swiotlb_update_mem_attributes();
#endif
return;
clean_guest_os_id:
wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
hv_ghcb_msr_write(HV_X64_MSR_GUEST_OS_ID, 0);
cpuhp_remove_state(cpuhp);
free_ghcb_page:
free_percpu(hv_ghcb_pg);
free_vp_assist_page:
kfree(hv_vp_assist_page);
hv_vp_assist_page = NULL;
common_free:
hv_common_free();
}
/*
* This routine is called before kexec/kdump, it does the required cleanup.
*/
void hyperv_cleanup(void)
{
union hv_x64_msr_hypercall_contents hypercall_msr;
unregister_syscore_ops(&hv_syscore_ops);
/* Reset our OS id */
wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
hv_ghcb_msr_write(HV_X64_MSR_GUEST_OS_ID, 0);
/*
* Reset hypercall page reference before reset the page,
* let hypercall operations fail safely rather than
* panic the kernel for using invalid hypercall page
*/
hv_hypercall_pg = NULL;
/* Reset the hypercall page */
hypercall_msr.as_uint64 = 0;
wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
/* Reset the TSC page */
hypercall_msr.as_uint64 = 0;
wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64);
}
void hyperv_report_panic(struct pt_regs *regs, long err, bool in_die)
{
static bool panic_reported;
u64 guest_id;
if (in_die && !panic_on_oops)
return;
/*
* We prefer to report panic on 'die' chain as we have proper
* registers to report, but if we miss it (e.g. on BUG()) we need
* to report it on 'panic'.
*/
if (panic_reported)
return;
panic_reported = true;
rdmsrl(HV_X64_MSR_GUEST_OS_ID, guest_id);
wrmsrl(HV_X64_MSR_CRASH_P0, err);
wrmsrl(HV_X64_MSR_CRASH_P1, guest_id);
wrmsrl(HV_X64_MSR_CRASH_P2, regs->ip);
wrmsrl(HV_X64_MSR_CRASH_P3, regs->ax);
wrmsrl(HV_X64_MSR_CRASH_P4, regs->sp);
/*
* Let Hyper-V know there is crash data available
*/
wrmsrl(HV_X64_MSR_CRASH_CTL, HV_CRASH_CTL_CRASH_NOTIFY);
}
EXPORT_SYMBOL_GPL(hyperv_report_panic);
bool hv_is_hyperv_initialized(void)
{
union hv_x64_msr_hypercall_contents hypercall_msr;
/*
* Ensure that we're really on Hyper-V, and not a KVM or Xen
* emulation of Hyper-V
*/
if (x86_hyper_type != X86_HYPER_MS_HYPERV)
return false;
/*
* Verify that earlier initialization succeeded by checking
* that the hypercall page is setup
*/
hypercall_msr.as_uint64 = 0;
rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
return hypercall_msr.enable;
}
EXPORT_SYMBOL_GPL(hv_is_hyperv_initialized);