From: Vitaly Kuznetsov <vkuznets@redhat.com>
Date: Fri, 21 May 2021 09:51:39 +0000 (+0200)
Subject: KVM: x86: hyper-v: Honor HV_MSR_HYPERCALL_AVAILABLE privilege bit
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=1561c2cb87ab39400d76998bf7be581c1e57f108;p=linux.git

KVM: x86: hyper-v: Honor HV_MSR_HYPERCALL_AVAILABLE privilege bit

HV_X64_MSR_GUEST_OS_ID/HV_X64_MSR_HYPERCALL are only available to guest
when HV_MSR_HYPERCALL_AVAILABLE bit is exposed.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-Id: <20210521095204.2161214-6-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index ab8dc23f05bf6..cb66842ccb8d4 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1205,6 +1205,18 @@ out_unlock:
 
 static bool hv_check_msr_access(struct kvm_vcpu_hv *hv_vcpu, u32 msr)
 {
+	if (!hv_vcpu->enforce_cpuid)
+		return true;
+
+	switch (msr) {
+	case HV_X64_MSR_GUEST_OS_ID:
+	case HV_X64_MSR_HYPERCALL:
+		return hv_vcpu->cpuid_cache.features_eax &
+			HV_MSR_HYPERCALL_AVAILABLE;
+	default:
+		break;
+	}
+
 	return true;
 }