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linux/arch/x86/kvm/hyperv.h
Maciej S. Szmigiero d52734d00b KVM: x86: Give a hint when Win2016 might fail to boot due to XSAVES erratum 
Since commit b0563468ee ("x86/CPU/AMD: Disable XSAVES on AMD family 0x17")
kernel unconditionally clears the XSAVES CPU feature bit on Zen1/2 CPUs.

Because KVM CPU caps are initialized from the kernel boot CPU features this
makes the XSAVES feature also unavailable for KVM guests in this case.
At the same time the XSAVEC feature is left enabled.

Unfortunately, having XSAVEC but no XSAVES in CPUID breaks Hyper-V enabled
Windows Server 2016 VMs that have more than one vCPU.

Let's at least give users hint in the kernel log what could be wrong since
these VMs currently simply hang at boot with a black screen - giving no
clue what suddenly broke them and how to make them work again.

Trigger the kernel message hint based on the particular guest ID written to
the Guest OS Identity Hyper-V MSR implemented by KVM.

Defer this check to when the L1 Hyper-V hypervisor enables SVM in EFER
since we want to limit this message to Hyper-V enabled Windows guests only
(Windows session running nested as L2) but the actual Guest OS Identity MSR
write is done by L1 and happens before it enables SVM.

Fixes: b0563468ee ("x86/CPU/AMD: Disable XSAVES on AMD family 0x17")
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Message-Id: <b83ab45c5e239e5d148b0ae7750133a67ac9575c.1706127425.git.maciej.szmigiero@oracle.com>
[Move some checks before mutex_lock(), rename function. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2024-01-31 16:21:00 -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"
#ifdef CONFIG_KVM_HYPERV
/* "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);
static inline bool kvm_hv_synic_has_vector(struct kvm_vcpu *vcpu, int vector)
{
return to_hv_vcpu(vcpu) && test_bit(vector, to_hv_synic(vcpu)->vec_bitmap);
}
static inline bool kvm_hv_synic_auto_eoi_set(struct kvm_vcpu *vcpu, int vector)
{
return to_hv_vcpu(vcpu) &&
test_bit(vector, to_hv_synic(vcpu)->auto_eoi_bitmap);
}
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_xsaves_xsavec_maybe_warn(struct kvm_vcpu *vcpu);
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);
}
static inline void kvm_hv_nested_transtion_tlb_flush(struct kvm_vcpu *vcpu,
bool tdp_enabled)
{
/*
* KVM_REQ_HV_TLB_FLUSH flushes entries from either L1's VP_ID or
* L2's VP_ID upon request from the guest. Make sure we check for
* pending entries in the right FIFO upon L1/L2 transition as these
* requests are put by other vCPUs asynchronously.
*/
if (to_hv_vcpu(vcpu) && tdp_enabled)
kvm_make_request(KVM_REQ_HV_TLB_FLUSH, vcpu);
}
int kvm_hv_vcpu_flush_tlb(struct kvm_vcpu *vcpu);
#else /* CONFIG_KVM_HYPERV */
static inline void kvm_hv_setup_tsc_page(struct kvm *kvm,
struct pvclock_vcpu_time_info *hv_clock) {}
static inline void kvm_hv_request_tsc_page_update(struct kvm *kvm) {}
static inline void kvm_hv_xsaves_xsavec_maybe_warn(struct kvm_vcpu *vcpu) {}
static inline void kvm_hv_init_vm(struct kvm *kvm) {}
static inline void kvm_hv_destroy_vm(struct kvm *kvm) {}
static inline int kvm_hv_vcpu_init(struct kvm_vcpu *vcpu)
{
return 0;
}
static inline void kvm_hv_vcpu_uninit(struct kvm_vcpu *vcpu) {}
static inline bool kvm_hv_hypercall_enabled(struct kvm_vcpu *vcpu)
{
return false;
}
static inline int kvm_hv_hypercall(struct kvm_vcpu *vcpu)
{
return HV_STATUS_ACCESS_DENIED;
}
static inline void kvm_hv_vcpu_purge_flush_tlb(struct kvm_vcpu *vcpu) {}
static inline void kvm_hv_free_pa_page(struct kvm *kvm) {}
static inline bool kvm_hv_synic_has_vector(struct kvm_vcpu *vcpu, int vector)
{
return false;
}
static inline bool kvm_hv_synic_auto_eoi_set(struct kvm_vcpu *vcpu, int vector)
{
return false;
}
static inline void kvm_hv_synic_send_eoi(struct kvm_vcpu *vcpu, int vector) {}
static inline bool kvm_hv_invtsc_suppressed(struct kvm_vcpu *vcpu)
{
return false;
}
static inline void kvm_hv_set_cpuid(struct kvm_vcpu *vcpu, bool hyperv_enabled) {}
static inline bool kvm_hv_has_stimer_pending(struct kvm_vcpu *vcpu)
{
return false;
}
static inline bool kvm_hv_is_tlb_flush_hcall(struct kvm_vcpu *vcpu)
{
return false;
}
static inline bool guest_hv_cpuid_has_l2_tlb_flush(struct kvm_vcpu *vcpu)
{
return false;
}
static inline int kvm_hv_verify_vp_assist(struct kvm_vcpu *vcpu)
{
return 0;
}
static inline u32 kvm_hv_get_vpindex(struct kvm_vcpu *vcpu)
{
return vcpu->vcpu_idx;
}
static inline void kvm_hv_nested_transtion_tlb_flush(struct kvm_vcpu *vcpu, bool tdp_enabled) {}
#endif /* CONFIG_KVM_HYPERV */
#endif /* __ARCH_X86_KVM_HYPERV_H__ */
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