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linux/arch/x86/kvm/hyperv.h
Vitaly Kuznetsov 2be1bd3a70 KVM: x86: Hyper-V invariant TSC control 
Normally, genuine Hyper-V doesn't expose architectural invariant TSC
(CPUID.80000007H:EDX[8]) to its guests by default. A special PV MSR
(HV_X64_MSR_TSC_INVARIANT_CONTROL, 0x40000118) and corresponding CPUID
feature bit (CPUID.0x40000003.EAX[15]) were introduced. When bit 0 of the
PV MSR is set, invariant TSC bit starts to show up in CPUID. When the
feature is exposed to Hyper-V guests, reenlightenment becomes unneeded.

Add the feature to KVM. Keep CPUID output intact when the feature
wasn't exposed to L1 and implement the required logic for hiding
invariant TSC when the feature was exposed and invariant TSC control
MSR wasn't written to. Copy genuine Hyper-V behavior and forbid to
disable the feature once it was enabled.

For the reference, for linux guests, support for the feature was added
in commit dce7cd6275 ("x86/hyperv: Allow guests to enable InvariantTSC").

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20221013095849.705943-4-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-12-29 15:33:29 -05:00

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/* 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>
#include "x86.h"
/* "Hv#1" signature */
#define HYPERV_CPUID_SIGNATURE_EAX 0x31237648
/*
* 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);
int kvm_hv_get_assist_page(struct kvm_vcpu *vcpu);
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);
}
/*
* With HV_ACCESS_TSC_INVARIANT feature, invariant TSC (CPUID.80000007H:EDX[8])
* is only observed after HV_X64_MSR_TSC_INVARIANT_CONTROL was written to.
*/
static inline bool kvm_hv_invtsc_suppressed(struct kvm_vcpu *vcpu)
{
struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
/*
* If Hyper-V's invariant TSC control is not exposed to the guest,
* the invariant TSC CPUID flag is not suppressed, Windows guests were
* observed to be able to handle it correctly. Going forward, VMMs are
* encouraged to enable Hyper-V's invariant TSC control when invariant
* TSC CPUID flag is set to make KVM's behavior match genuine Hyper-V.
*/
if (!hv_vcpu ||
!(hv_vcpu->cpuid_cache.features_eax & HV_ACCESS_TSC_INVARIANT))
return false;
/*
* If Hyper-V's invariant TSC control is exposed to the guest, KVM is
* responsible for suppressing the invariant TSC CPUID flag if the
* Hyper-V control is not enabled.
*/
return !(to_kvm_hv(vcpu->kvm)->hv_invtsc_control & HV_EXPOSE_INVARIANT_TSC);
}
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);
int kvm_hv_vcpu_init(struct kvm_vcpu *vcpu);
void kvm_hv_set_cpuid(struct kvm_vcpu *vcpu, bool hyperv_enabled);
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);
static inline struct kvm_vcpu_hv_tlb_flush_fifo *kvm_hv_get_tlb_flush_fifo(struct kvm_vcpu *vcpu,
bool is_guest_mode)
{
struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
int i = is_guest_mode ? HV_L2_TLB_FLUSH_FIFO :
HV_L1_TLB_FLUSH_FIFO;
return &hv_vcpu->tlb_flush_fifo[i];
}
static inline void kvm_hv_vcpu_purge_flush_tlb(struct kvm_vcpu *vcpu)
{
struct kvm_vcpu_hv_tlb_flush_fifo *tlb_flush_fifo;
if (!to_hv_vcpu(vcpu) || !kvm_check_request(KVM_REQ_HV_TLB_FLUSH, vcpu))
return;
tlb_flush_fifo = kvm_hv_get_tlb_flush_fifo(vcpu, is_guest_mode(vcpu));
kfifo_reset_out(&tlb_flush_fifo->entries);
}
static inline bool guest_hv_cpuid_has_l2_tlb_flush(struct kvm_vcpu *vcpu)
{
struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
return hv_vcpu &&
(hv_vcpu->cpuid_cache.nested_eax & HV_X64_NESTED_DIRECT_FLUSH);
}
static inline bool kvm_hv_is_tlb_flush_hcall(struct kvm_vcpu *vcpu)
{
struct kvm_vcpu_hv *hv_vcpu = to_hv_vcpu(vcpu);
u16 code;
if (!hv_vcpu)
return false;
code = is_64_bit_hypercall(vcpu) ? kvm_rcx_read(vcpu) :
kvm_rax_read(vcpu);
return (code == HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE ||
code == HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST ||
code == HVCALL_FLUSH_VIRTUAL_ADDRESS_SPACE_EX ||
code == HVCALL_FLUSH_VIRTUAL_ADDRESS_LIST_EX);
}
static inline int kvm_hv_verify_vp_assist(struct kvm_vcpu *vcpu)
{
if (!to_hv_vcpu(vcpu))
return 0;
if (!kvm_hv_assist_page_enabled(vcpu))
return 0;
return kvm_hv_get_assist_page(vcpu);
}
int kvm_hv_vcpu_flush_tlb(struct kvm_vcpu *vcpu);
#endif
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