diff --git a/Documentation/virtual/kvm/api.txt b/Documentation/virtual/kvm/api.txt
index f2c345f7b630..356156f5c52d 100644
--- a/Documentation/virtual/kvm/api.txt
+++ b/Documentation/virtual/kvm/api.txt
@@ -3800,6 +3800,62 @@ is enabled; for more information, see the description of the capability.
However, it can always be used as long as KVM_CHECK_EXTENSION confirms
that KVM_CAP_MANUAL_DIRTY_LOG_PROTECT is present.
+4.118 KVM_GET_SUPPORTED_HV_CPUID
+
+Capability: KVM_CAP_HYPERV_CPUID
+Architectures: x86
+Type: vcpu ioctl
+Parameters: struct kvm_cpuid2 (in/out)
+Returns: 0 on success, -1 on error
+
+struct kvm_cpuid2 {
+ __u32 nent;
+ __u32 padding;
+ struct kvm_cpuid_entry2 entries[0];
+};
+
+struct kvm_cpuid_entry2 {
+ __u32 function;
+ __u32 index;
+ __u32 flags;
+ __u32 eax;
+ __u32 ebx;
+ __u32 ecx;
+ __u32 edx;
+ __u32 padding[3];
+};
+
+This ioctl returns x86 cpuid features leaves related to Hyper-V emulation in
+KVM. Userspace can use the information returned by this ioctl to construct
+cpuid information presented to guests consuming Hyper-V enlightenments (e.g.
+Windows or Hyper-V guests).
+
+CPUID feature leaves returned by this ioctl are defined by Hyper-V Top Level
+Functional Specification (TLFS). These leaves can't be obtained with
+KVM_GET_SUPPORTED_CPUID ioctl because some of them intersect with KVM feature
+leaves (0x40000000, 0x40000001).
+
+Currently, the following list of CPUID leaves are returned:
+ HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS
+ HYPERV_CPUID_INTERFACE
+ HYPERV_CPUID_VERSION
+ HYPERV_CPUID_FEATURES
+ HYPERV_CPUID_ENLIGHTMENT_INFO
+ HYPERV_CPUID_IMPLEMENT_LIMITS
+ HYPERV_CPUID_NESTED_FEATURES
+
+HYPERV_CPUID_NESTED_FEATURES leaf is only exposed when Enlightened VMCS was
+enabled on the corresponding vCPU (KVM_CAP_HYPERV_ENLIGHTENED_VMCS).
+
+Userspace invokes KVM_GET_SUPPORTED_CPUID by passing a kvm_cpuid2 structure
+with the 'nent' field indicating the number of entries in the variable-size
+array 'entries'. If the number of entries is too low to describe all Hyper-V
+feature leaves, an error (E2BIG) is returned. If the number is more or equal
+to the number of Hyper-V feature leaves, the 'nent' field is adjusted to the
+number of valid entries in the 'entries' array, which is then filled.
+
+'index' and 'flags' fields in 'struct kvm_cpuid_entry2' are currently reserved,
+userspace should not expect to get any particular value there.
5. The kvm_run structure
------------------------
diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index a9b5d6c4e3eb..e3c076020d4e 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1752,3 +1752,124 @@ int kvm_vm_ioctl_hv_eventfd(struct kvm *kvm, struct kvm_hyperv_eventfd *args)
return kvm_hv_eventfd_deassign(kvm, args->conn_id);
return kvm_hv_eventfd_assign(kvm, args->conn_id, args->fd);
}
+
+int kvm_vcpu_ioctl_get_hv_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid,
+ struct kvm_cpuid_entry2 __user *entries)
+{
+ uint16_t evmcs_ver = kvm_x86_ops->nested_get_evmcs_version(vcpu);
+ struct kvm_cpuid_entry2 cpuid_entries[] = {
+ { .function = HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS },
+ { .function = HYPERV_CPUID_INTERFACE },
+ { .function = HYPERV_CPUID_VERSION },
+ { .function = HYPERV_CPUID_FEATURES },
+ { .function = HYPERV_CPUID_ENLIGHTMENT_INFO },
+ { .function = HYPERV_CPUID_IMPLEMENT_LIMITS },
+ { .function = HYPERV_CPUID_NESTED_FEATURES },
+ };
+ int i, nent = ARRAY_SIZE(cpuid_entries);
+
+ /* Skip NESTED_FEATURES if eVMCS is not supported */
+ if (!evmcs_ver)
+ --nent;
+
+ if (cpuid->nent < nent)
+ return -E2BIG;
+
+ if (cpuid->nent > nent)
+ cpuid->nent = nent;
+
+ for (i = 0; i < nent; i++) {
+ struct kvm_cpuid_entry2 *ent = &cpuid_entries[i];
+ u32 signature[3];
+
+ switch (ent->function) {
+ case HYPERV_CPUID_VENDOR_AND_MAX_FUNCTIONS:
+ memcpy(signature, "Linux KVM Hv", 12);
+
+ ent->eax = HYPERV_CPUID_NESTED_FEATURES;
+ ent->ebx = signature[0];
+ ent->ecx = signature[1];
+ ent->edx = signature[2];
+ break;
+
+ case HYPERV_CPUID_INTERFACE:
+ memcpy(signature, "Hv#1\0\0\0\0\0\0\0\0", 12);
+ ent->eax = signature[0];
+ break;
+
+ case HYPERV_CPUID_VERSION:
+ /*
+ * We implement some Hyper-V 2016 functions so let's use
+ * this version.
+ */
+ ent->eax = 0x00003839;
+ ent->ebx = 0x000A0000;
+ break;
+
+ case HYPERV_CPUID_FEATURES:
+ ent->eax |= HV_X64_MSR_VP_RUNTIME_AVAILABLE;
+ ent->eax |= HV_MSR_TIME_REF_COUNT_AVAILABLE;
+ ent->eax |= HV_X64_MSR_SYNIC_AVAILABLE;
+ ent->eax |= HV_MSR_SYNTIMER_AVAILABLE;
+ ent->eax |= HV_X64_MSR_APIC_ACCESS_AVAILABLE;
+ ent->eax |= HV_X64_MSR_HYPERCALL_AVAILABLE;
+ ent->eax |= HV_X64_MSR_VP_INDEX_AVAILABLE;
+ ent->eax |= HV_X64_MSR_RESET_AVAILABLE;
+ ent->eax |= HV_MSR_REFERENCE_TSC_AVAILABLE;
+ ent->eax |= HV_X64_MSR_GUEST_IDLE_AVAILABLE;
+ ent->eax |= HV_X64_ACCESS_FREQUENCY_MSRS;
+ ent->eax |= HV_X64_ACCESS_REENLIGHTENMENT;
+
+ ent->ebx |= HV_X64_POST_MESSAGES;
+ ent->ebx |= HV_X64_SIGNAL_EVENTS;
+
+ ent->edx |= HV_FEATURE_FREQUENCY_MSRS_AVAILABLE;
+ ent->edx |= HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE;
+ ent->edx |= HV_STIMER_DIRECT_MODE_AVAILABLE;
+
+ break;
+
+ case HYPERV_CPUID_ENLIGHTMENT_INFO:
+ ent->eax |= HV_X64_REMOTE_TLB_FLUSH_RECOMMENDED;
+ ent->eax |= HV_X64_APIC_ACCESS_RECOMMENDED;
+ ent->eax |= HV_X64_SYSTEM_RESET_RECOMMENDED;
+ ent->eax |= HV_X64_RELAXED_TIMING_RECOMMENDED;
+ ent->eax |= HV_X64_CLUSTER_IPI_RECOMMENDED;
+ ent->eax |= HV_X64_EX_PROCESSOR_MASKS_RECOMMENDED;
+ ent->eax |= HV_X64_ENLIGHTENED_VMCS_RECOMMENDED;
+
+ /*
+ * Default number of spinlock retry attempts, matches
+ * HyperV 2016.
+ */
+ ent->ebx = 0x00000FFF;
+
+ break;
+
+ case HYPERV_CPUID_IMPLEMENT_LIMITS:
+ /* Maximum number of virtual processors */
+ ent->eax = KVM_MAX_VCPUS;
+ /*
+ * Maximum number of logical processors, matches
+ * HyperV 2016.
+ */
+ ent->ebx = 64;
+
+ break;
+
+ case HYPERV_CPUID_NESTED_FEATURES:
+ ent->eax = evmcs_ver;
+
+ break;
+
+ default:
+ break;
+ }
+ }
+
+ if (copy_to_user(entries, cpuid_entries,
+ nent * sizeof(struct kvm_cpuid_entry2)))
+ return -EFAULT;
+
+ return 0;
+}
diff --git a/arch/x86/kvm/hyperv.h b/arch/x86/kvm/hyperv.h
index 9c21c3479899..fd7cf13a2144 100644
--- a/arch/x86/kvm/hyperv.h
+++ b/arch/x86/kvm/hyperv.h
@@ -97,5 +97,7 @@ void kvm_hv_setup_tsc_page(struct kvm *kvm,
void kvm_hv_init_vm(struct kvm *kvm);
void kvm_hv_destroy_vm(struct kvm *kvm);
int kvm_vm_ioctl_hv_eventfd(struct kvm *kvm, struct kvm_hyperv_eventfd *args);
+int kvm_vcpu_ioctl_get_hv_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid2 *cpuid,
+ struct kvm_cpuid_entry2 __user *entries);
#endif
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 54ef79421c6b..18b7817af2bc 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2997,6 +2997,7 @@ 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_ENLIGHTENED_VMCS:
+ case KVM_CAP_HYPERV_CPUID:
case KVM_CAP_PCI_SEGMENT:
case KVM_CAP_DEBUGREGS:
case KVM_CAP_X86_ROBUST_SINGLESTEP:
@@ -4191,6 +4192,25 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
r = kvm_x86_ops->set_nested_state(vcpu, user_kvm_nested_state, &kvm_state);
break;
}
+ case KVM_GET_SUPPORTED_HV_CPUID: {
+ struct kvm_cpuid2 __user *cpuid_arg = argp;
+ struct kvm_cpuid2 cpuid;
+
+ r = -EFAULT;
+ if (copy_from_user(&cpuid, cpuid_arg, sizeof(cpuid)))
+ goto out;
+
+ r = kvm_vcpu_ioctl_get_hv_cpuid(vcpu, &cpuid,
+ cpuid_arg->entries);
+ if (r)
+ goto out;
+
+ r = -EFAULT;
+ if (copy_to_user(cpuid_arg, &cpuid, sizeof(cpuid)))
+ goto out;
+ r = 0;
+ break;
+ }
default:
r = -EINVAL;
}
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 9fe35f1ac938..6d4ea4b6c922 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -987,6 +987,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_EXCEPTION_PAYLOAD 164
#define KVM_CAP_ARM_VM_IPA_SIZE 165
#define KVM_CAP_MANUAL_DIRTY_LOG_PROTECT 166
+#define KVM_CAP_HYPERV_CPUID 167
#ifdef KVM_CAP_IRQ_ROUTING
@@ -1436,6 +1437,9 @@ struct kvm_enc_region {
/* Available with KVM_CAP_MANUAL_DIRTY_LOG_PROTECT */
#define KVM_CLEAR_DIRTY_LOG _IOWR(KVMIO, 0xc0, struct kvm_clear_dirty_log)
+/* Available with KVM_CAP_HYPERV_CPUID */
+#define KVM_GET_SUPPORTED_HV_CPUID _IOWR(KVMIO, 0xc1, struct kvm_cpuid2)
+
/* Secure Encrypted Virtualization command */
enum sev_cmd_id {
/* Guest initialization commands */