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KVM: x86: hyper-v: Introduce KVM_CAP_HYPERV_ENFORCE_CPUID

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Modeled after KVM_CAP_ENFORCE_PV_FEATURE_CPUID, the new capability allows
for limiting Hyper-V features to those exposed to the guest in Hyper-V
CPUIDs (0x40000003, 0x40000004, ...).

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-3-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Vitaly Kuznetsov 2021-05-21 11:51:36 +02:00 committed by Paolo Bonzini
parent f15cdceab5
commit 644f706719
6 changed files with 39 additions and 0 deletions
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11
Documentation/virt/kvm/api.rst
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@ -6891,3 +6891,14 @@ This capability is always enabled.
This capability indicates that the KVM virtual PTP service is
supported in the host. A VMM can check whether the service is
available to the guest on migration.
8.33 KVM_CAP_HYPERV_ENFORCE_CPUID
-----------------------------
Architectures: x86
When enabled, KVM will disable emulated Hyper-V features provided to the
guest according to the bits Hyper-V CPUID feature leaves. Otherwise, all
currently implmented Hyper-V features are provided unconditionally when
Hyper-V identification is set in the HYPERV_CPUID_INTERFACE (0x40000001)
leaf.

1
arch/x86/include/asm/kvm_host.h
View File

@ -543,6 +543,7 @@ struct kvm_vcpu_hv {
struct kvm_vcpu_hv_stimer stimer[HV_SYNIC_STIMER_COUNT];
DECLARE_BITMAP(stimer_pending_bitmap, HV_SYNIC_STIMER_COUNT);
cpumask_t tlb_flush;
bool enforce_cpuid;
};
/* Xen HVM per vcpu emulation context */

21
arch/x86/kvm/hyperv.c
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@ -1853,6 +1853,27 @@ void kvm_hv_set_cpuid(struct kvm_vcpu *vcpu)
vcpu->arch.hyperv_enabled = false;
}
int kvm_hv_set_enforce_cpuid(struct kvm_vcpu *vcpu, bool enforce)
{
struct kvm_vcpu_hv *hv_vcpu;
int ret = 0;
if (!to_hv_vcpu(vcpu)) {
if (enforce) {
ret = kvm_hv_vcpu_init(vcpu);
if (ret)
return ret;
} else {
return 0;
}
}
hv_vcpu = to_hv_vcpu(vcpu);
hv_vcpu->enforce_cpuid = enforce;
return ret;
}
bool kvm_hv_hypercall_enabled(struct kvm_vcpu *vcpu)
{
return vcpu->arch.hyperv_enabled && to_kvm_hv(vcpu->kvm)->hv_guest_os_id;

1
arch/x86/kvm/hyperv.h
View File

@ -138,6 +138,7 @@ void kvm_hv_invalidate_tsc_page(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);

4
arch/x86/kvm/x86.c
View File

@ -3955,6 +3955,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
case KVM_CAP_HYPERV_TLBFLUSH:
case KVM_CAP_HYPERV_SEND_IPI:
case KVM_CAP_HYPERV_CPUID:
case KVM_CAP_HYPERV_ENFORCE_CPUID:
case KVM_CAP_SYS_HYPERV_CPUID:
case KVM_CAP_PCI_SEGMENT:
case KVM_CAP_DEBUGREGS:
@ -4878,6 +4879,9 @@ static int kvm_vcpu_ioctl_enable_cap(struct kvm_vcpu *vcpu,
return static_call(kvm_x86_enable_direct_tlbflush)(vcpu);
case KVM_CAP_HYPERV_ENFORCE_CPUID:
return kvm_hv_set_enforce_cpuid(vcpu, cap->args[0]);
case KVM_CAP_ENFORCE_PV_FEATURE_CPUID:
vcpu->arch.pv_cpuid.enforce = cap->args[0];
if (vcpu->arch.pv_cpuid.enforce)

1
include/uapi/linux/kvm.h
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@ -1083,6 +1083,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_SGX_ATTRIBUTE 196
#define KVM_CAP_VM_COPY_ENC_CONTEXT_FROM 197
#define KVM_CAP_PTP_KVM 198
#define KVM_CAP_HYPERV_ENFORCE_CPUID 199
#ifdef KVM_CAP_IRQ_ROUTING