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@xxxxxxxxxx>
---
Documentation/virt/kvm/api.rst | 11 +++++++++++
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/kvm/hyperv.c | 21 +++++++++++++++++++++
arch/x86/kvm/hyperv.h | 1 +
arch/x86/kvm/x86.c | 4 ++++
include/uapi/linux/kvm.h | 1 +
6 files changed, 39 insertions(+)
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 7fcb2fd38f42..80154d5d98a1 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -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.
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 55efbacfc244..7c739999441b 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -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 */
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index f98370a39936..557897c453a9 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1809,6 +1809,27 @@ 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;
diff --git a/arch/x86/kvm/hyperv.h b/arch/x86/kvm/hyperv.h
index 60547d5cb6d7..730da8537d05 100644
--- a/arch/x86/kvm/hyperv.h
+++ b/arch/x86/kvm/hyperv.h
@@ -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);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 9b6bca616929..36b99ae1eb60 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3862,6 +3862,7 @@ 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:
@@ -4790,6 +4791,9 @@ 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)
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 3fd9a7e9d90c..c2e46b4b94c7 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1082,6 +1082,7 @@ 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
--
2.31.1
