linux/arch/x86/kvm/hyperv.h
Vitaly Kuznetsov 42dcbe7d8b KVM: x86: hyper-v: Avoid writing to TSC page without an active vCPU
The following WARN is triggered from kvm_vm_ioctl_set_clock():
 WARNING: CPU: 10 PID: 579353 at arch/x86/kvm/../../../virt/kvm/kvm_main.c:3161 mark_page_dirty_in_slot+0x6c/0x80 [kvm]
 ...
 CPU: 10 PID: 579353 Comm: qemu-system-x86 Tainted: G        W  O      5.16.0.stable #20
 Hardware name: LENOVO 20UF001CUS/20UF001CUS, BIOS R1CET65W(1.34 ) 06/17/2021
 RIP: 0010:mark_page_dirty_in_slot+0x6c/0x80 [kvm]
 ...
 Call Trace:
  <TASK>
  ? kvm_write_guest+0x114/0x120 [kvm]
  kvm_hv_invalidate_tsc_page+0x9e/0xf0 [kvm]
  kvm_arch_vm_ioctl+0xa26/0xc50 [kvm]
  ? schedule+0x4e/0xc0
  ? __cond_resched+0x1a/0x50
  ? futex_wait+0x166/0x250
  ? __send_signal+0x1f1/0x3d0
  kvm_vm_ioctl+0x747/0xda0 [kvm]
  ...

The WARN was introduced by commit 03c0304a86bc ("KVM: Warn if
mark_page_dirty() is called without an active vCPU") but the change seems
to be correct (unlike Hyper-V TSC page update mechanism). In fact, there's
no real need to actually write to guest memory to invalidate TSC page, this
can be done by the first vCPU which goes through kvm_guest_time_update().

Reported-by: Maxim Levitsky <mlevitsk@redhat.com>
Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
Suggested-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20220407201013.963226-1-vkuznets@redhat.com>
2022-04-11 13:29:51 -04:00

151 lines
4.5 KiB
C

/* SPDX-License-Identifier: GPL-2.0-only */
/*
* KVM Microsoft Hyper-V emulation
*
* derived from arch/x86/kvm/x86.c
*
* Copyright (C) 2006 Qumranet, Inc.
* Copyright (C) 2008 Qumranet, Inc.
* Copyright IBM Corporation, 2008
* Copyright 2010 Red Hat, Inc. and/or its affiliates.
* Copyright (C) 2015 Andrey Smetanin <asmetanin@virtuozzo.com>
*
* Authors:
* Avi Kivity <avi@qumranet.com>
* Yaniv Kamay <yaniv@qumranet.com>
* Amit Shah <amit.shah@qumranet.com>
* Ben-Ami Yassour <benami@il.ibm.com>
* Andrey Smetanin <asmetanin@virtuozzo.com>
*/
#ifndef __ARCH_X86_KVM_HYPERV_H__
#define __ARCH_X86_KVM_HYPERV_H__
#include <linux/kvm_host.h>
/*
* The #defines related to the synthetic debugger are required by KDNet, but
* they are not documented in the Hyper-V TLFS because the synthetic debugger
* functionality has been deprecated and is subject to removal in future
* versions of Windows.
*/
#define HYPERV_CPUID_SYNDBG_VENDOR_AND_MAX_FUNCTIONS 0x40000080
#define HYPERV_CPUID_SYNDBG_INTERFACE 0x40000081
#define HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES 0x40000082
/*
* Hyper-V synthetic debugger platform capabilities
* These are HYPERV_CPUID_SYNDBG_PLATFORM_CAPABILITIES.EAX bits.
*/
#define HV_X64_SYNDBG_CAP_ALLOW_KERNEL_DEBUGGING BIT(1)
/* Hyper-V Synthetic debug options MSR */
#define HV_X64_MSR_SYNDBG_CONTROL 0x400000F1
#define HV_X64_MSR_SYNDBG_STATUS 0x400000F2
#define HV_X64_MSR_SYNDBG_SEND_BUFFER 0x400000F3
#define HV_X64_MSR_SYNDBG_RECV_BUFFER 0x400000F4
#define HV_X64_MSR_SYNDBG_PENDING_BUFFER 0x400000F5
#define HV_X64_MSR_SYNDBG_OPTIONS 0x400000FF
/* Hyper-V HV_X64_MSR_SYNDBG_OPTIONS bits */
#define HV_X64_SYNDBG_OPTION_USE_HCALLS BIT(2)
static inline struct kvm_hv *to_kvm_hv(struct kvm *kvm)
{
return &kvm->arch.hyperv;
}
static inline struct kvm_vcpu_hv *to_hv_vcpu(struct kvm_vcpu *vcpu)
{
return vcpu->arch.hyperv;
}
static inline struct kvm_vcpu_hv_synic *to_hv_synic(struct kvm_vcpu *vcpu)
{
struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
return &hv_vcpu->synic;
}
static inline struct kvm_vcpu *hv_synic_to_vcpu(struct kvm_vcpu_hv_synic *synic)
{
struct kvm_vcpu_hv *hv_vcpu = container_of(synic, struct kvm_vcpu_hv, synic);
return hv_vcpu->vcpu;
}
static inline struct kvm_hv_syndbg *to_hv_syndbg(struct kvm_vcpu *vcpu)
{
return &vcpu->kvm->arch.hyperv.hv_syndbg;
}
static inline u32 kvm_hv_get_vpindex(struct kvm_vcpu *vcpu)
{
struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
return hv_vcpu ? hv_vcpu->vp_index : vcpu->vcpu_idx;
}
int kvm_hv_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data, bool host);
int kvm_hv_get_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata, bool host);
static inline bool kvm_hv_hypercall_enabled(struct kvm_vcpu *vcpu)
{
return vcpu->arch.hyperv_enabled && to_kvm_hv(vcpu->kvm)->hv_guest_os_id;
}
int kvm_hv_hypercall(struct kvm_vcpu *vcpu);
void kvm_hv_irq_routing_update(struct kvm *kvm);
int kvm_hv_synic_set_irq(struct kvm *kvm, u32 vcpu_id, u32 sint);
void kvm_hv_synic_send_eoi(struct kvm_vcpu *vcpu, int vector);
int kvm_hv_activate_synic(struct kvm_vcpu *vcpu, bool dont_zero_synic_pages);
void kvm_hv_vcpu_uninit(struct kvm_vcpu *vcpu);
bool kvm_hv_assist_page_enabled(struct kvm_vcpu *vcpu);
bool kvm_hv_get_assist_page(struct kvm_vcpu *vcpu,
struct hv_vp_assist_page *assist_page);
static inline struct kvm_vcpu_hv_stimer *to_hv_stimer(struct kvm_vcpu *vcpu,
int timer_index)
{
return &to_hv_vcpu(vcpu)->stimer[timer_index];
}
static inline struct kvm_vcpu *hv_stimer_to_vcpu(struct kvm_vcpu_hv_stimer *stimer)
{
struct kvm_vcpu_hv *hv_vcpu;
hv_vcpu = container_of(stimer - stimer->index, struct kvm_vcpu_hv,
stimer[0]);
return hv_vcpu->vcpu;
}
static inline bool kvm_hv_has_stimer_pending(struct kvm_vcpu *vcpu)
{
struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
if (!hv_vcpu)
return false;
return !bitmap_empty(hv_vcpu->stimer_pending_bitmap,
HV_SYNIC_STIMER_COUNT);
}
void kvm_hv_process_stimers(struct kvm_vcpu *vcpu);
void kvm_hv_setup_tsc_page(struct kvm *kvm,
struct pvclock_vcpu_time_info *hv_clock);
void kvm_hv_request_tsc_page_update(struct kvm *kvm);
void kvm_hv_init_vm(struct kvm *kvm);
void kvm_hv_destroy_vm(struct kvm *kvm);
void kvm_hv_set_cpuid(struct kvm_vcpu *vcpu);
int kvm_hv_set_enforce_cpuid(struct kvm_vcpu *vcpu, bool enforce);
int kvm_vm_ioctl_hv_eventfd(struct kvm *kvm, struct kvm_hyperv_eventfd *args);
int kvm_get_hv_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid,
struct kvm_cpuid_entry2 __user *entries);
#endif