https://github.com/torvalds/linux
Tip revision: d012a7190fc1fd72ed48911e77ca97ba4521bccd authored by Linus Torvalds on 23 August 2020, 21:08:43 UTC
Linux 5.9-rc2
Linux 5.9-rc2
Tip revision: d012a71
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/acpi.h>
#include <linux/efi.h>
#include <linux/types.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/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>
void *hv_hypercall_pg;
EXPORT_SYMBOL_GPL(hv_hypercall_pg);
/* Storage to save the hypercall page temporarily for hibernation */
static void *hv_hypercall_pg_saved;
u32 *hv_vp_index;
EXPORT_SYMBOL_GPL(hv_vp_index);
struct hv_vp_assist_page **hv_vp_assist_page;
EXPORT_SYMBOL_GPL(hv_vp_assist_page);
void __percpu **hyperv_pcpu_input_arg;
EXPORT_SYMBOL_GPL(hyperv_pcpu_input_arg);
u32 hv_max_vp_index;
EXPORT_SYMBOL_GPL(hv_max_vp_index);
void *hv_alloc_hyperv_page(void)
{
BUILD_BUG_ON(PAGE_SIZE != HV_HYP_PAGE_SIZE);
return (void *)__get_free_page(GFP_KERNEL);
}
EXPORT_SYMBOL_GPL(hv_alloc_hyperv_page);
void *hv_alloc_hyperv_zeroed_page(void)
{
BUILD_BUG_ON(PAGE_SIZE != HV_HYP_PAGE_SIZE);
return (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
}
EXPORT_SYMBOL_GPL(hv_alloc_hyperv_zeroed_page);
void hv_free_hyperv_page(unsigned long addr)
{
free_page(addr);
}
EXPORT_SYMBOL_GPL(hv_free_hyperv_page);
static int hv_cpu_init(unsigned int cpu)
{
u64 msr_vp_index;
struct hv_vp_assist_page **hvp = &hv_vp_assist_page[smp_processor_id()];
void **input_arg;
struct page *pg;
input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
/* hv_cpu_init() can be called with IRQs disabled from hv_resume() */
pg = alloc_page(irqs_disabled() ? GFP_ATOMIC : GFP_KERNEL);
if (unlikely(!pg))
return -ENOMEM;
*input_arg = page_address(pg);
hv_get_vp_index(msr_vp_index);
hv_vp_index[smp_processor_id()] = msr_vp_index;
if (msr_vp_index > hv_max_vp_index)
hv_max_vp_index = msr_vp_index;
if (!hv_vp_assist_page)
return 0;
/*
* 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.
*/
if (!*hvp) {
*hvp = __vmalloc(PAGE_SIZE, GFP_KERNEL | __GFP_ZERO);
}
if (*hvp) {
u64 val;
val = vmalloc_to_pfn(*hvp);
val = (val << HV_X64_MSR_VP_ASSIST_PAGE_ADDRESS_SHIFT) |
HV_X64_MSR_VP_ASSIST_PAGE_ENABLE;
wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, val);
}
return 0;
}
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 priviliges to make TSC frequency
* change notifications work.
*/
return ms_hyperv.features & HV_X64_ACCESS_FREQUENCY_MSRS &&
ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE &&
ms_hyperv.features & HV_X64_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,
.target_vp = hv_vp_index[smp_processor_id()]
};
struct hv_tsc_emulation_control emu_ctrl = {.enabled = 1};
if (!hv_reenlightenment_available()) {
pr_warn("Hyper-V: reenlightenment support is unavailable\n");
return;
}
hv_reenlightenment_cb = cb;
/* Make sure callback is registered before we write to MSRs */
wmb();
wrmsrl(HV_X64_MSR_REENLIGHTENMENT_CONTROL, *((u64 *)&re_ctrl));
wrmsrl(HV_X64_MSR_TSC_EMULATION_CONTROL, *((u64 *)&emu_ctrl));
}
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;
unsigned long flags;
void **input_arg;
void *input_pg = NULL;
local_irq_save(flags);
input_arg = (void **)this_cpu_ptr(hyperv_pcpu_input_arg);
input_pg = *input_arg;
*input_arg = NULL;
local_irq_restore(flags);
free_page((unsigned long)input_pg);
if (hv_vp_assist_page && hv_vp_assist_page[cpu])
wrmsrl(HV_X64_MSR_VP_ASSIST_PAGE, 0);
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;
/*
* Reset the hypercall page as it is going to be invalidated
* accross 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,
};
/*
* 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, required_msrs;
union hv_x64_msr_hypercall_contents hypercall_msr;
int cpuhp, i;
if (x86_hyper_type != X86_HYPER_MS_HYPERV)
return;
/* Absolutely required MSRs */
required_msrs = HV_X64_MSR_HYPERCALL_AVAILABLE |
HV_X64_MSR_VP_INDEX_AVAILABLE;
if ((ms_hyperv.features & required_msrs) != required_msrs)
return;
/*
* Allocate the per-CPU state for the hypercall input arg.
* If this allocation fails, we will not be able to setup
* (per-CPU) hypercall input page and thus this failure is
* fatal on Hyper-V.
*/
hyperv_pcpu_input_arg = alloc_percpu(void *);
BUG_ON(hyperv_pcpu_input_arg == NULL);
/* Allocate percpu VP index */
hv_vp_index = kmalloc_array(num_possible_cpus(), sizeof(*hv_vp_index),
GFP_KERNEL);
if (!hv_vp_index)
return;
for (i = 0; i < num_possible_cpus(); i++)
hv_vp_index[i] = VP_INVAL;
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 free_vp_index;
}
cpuhp = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "x86/hyperv_init:online",
hv_cpu_init, hv_cpu_die);
if (cpuhp < 0)
goto free_vp_assist_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);
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) {
wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);
goto remove_cpuhp_state;
}
rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
hypercall_msr.enable = 1;
hypercall_msr.guest_physical_address = vmalloc_to_pfn(hv_hypercall_pg);
wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
/*
* Ignore any errors in setting up stimer clockevents
* as we can run with the LAPIC timer as a fallback.
*/
(void)hv_stimer_alloc();
hv_apic_init();
x86_init.pci.arch_init = hv_pci_init;
register_syscore_ops(&hv_syscore_ops);
return;
remove_cpuhp_state:
cpuhp_remove_state(cpuhp);
free_vp_assist_page:
kfree(hv_vp_assist_page);
hv_vp_assist_page = NULL;
free_vp_index:
kfree(hv_vp_index);
hv_vp_index = NULL;
}
/*
* 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);
/*
* 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);
}
EXPORT_SYMBOL_GPL(hyperv_cleanup);
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);
/**
* hyperv_report_panic_msg - report panic message to Hyper-V
* @pa: physical address of the panic page containing the message
* @size: size of the message in the page
*/
void hyperv_report_panic_msg(phys_addr_t pa, size_t size)
{
/*
* P3 to contain the physical address of the panic page & P4 to
* contain the size of the panic data in that page. Rest of the
* registers are no-op when the NOTIFY_MSG flag is set.
*/
wrmsrl(HV_X64_MSR_CRASH_P0, 0);
wrmsrl(HV_X64_MSR_CRASH_P1, 0);
wrmsrl(HV_X64_MSR_CRASH_P2, 0);
wrmsrl(HV_X64_MSR_CRASH_P3, pa);
wrmsrl(HV_X64_MSR_CRASH_P4, size);
/*
* Let Hyper-V know there is crash data available along with
* the panic message.
*/
wrmsrl(HV_X64_MSR_CRASH_CTL,
(HV_CRASH_CTL_CRASH_NOTIFY | HV_CRASH_CTL_CRASH_NOTIFY_MSG));
}
EXPORT_SYMBOL_GPL(hyperv_report_panic_msg);
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);
bool hv_is_hibernation_supported(void)
{
return acpi_sleep_state_supported(ACPI_STATE_S4);
}
EXPORT_SYMBOL_GPL(hv_is_hibernation_supported);