linux-kernel - [PATCH RFC 13/22] KVM: x86: hyper-v: Honor HV_ACCESS

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Date:   Tue, 13 Apr 2021 14:26:21 +0200
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     kvm@...r.kernel.org, Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Siddharth Chandrasekaran <sidcha@...zon.de>,
        linux-kernel@...r.kernel.org, linux-hyperv@...r.kernel.org
Subject: [PATCH RFC 13/22] KVM: x86: hyper-v: Honor HV_ACCESS_REENLIGHTENMENT privilege bit

HV_X64_MSR_REENLIGHTENMENT_CONTROL/HV_X64_MSR_TSC_EMULATION_CONTROL/
HV_X64_MSR_TSC_EMULATION_STATUS are only available to guest when
HV_ACCESS_REENLIGHTENMENT bit is exposed.

Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
---
 arch/x86/kvm/hyperv.c | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index e92a1109ad9b..259badd3a139 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1330,13 +1330,22 @@ static int kvm_hv_set_msr_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data,
 		}
 		break;
 	case HV_X64_MSR_REENLIGHTENMENT_CONTROL:
+		if (unlikely(!host && !(hv_vcpu->cpuid_cache.features_eax &
+					HV_ACCESS_REENLIGHTENMENT)))
+			return 1;
+
 		hv->hv_reenlightenment_control = data;
 		break;
 	case HV_X64_MSR_TSC_EMULATION_CONTROL:
+		if (unlikely(!host && !(hv_vcpu->cpuid_cache.features_eax &
+					HV_ACCESS_REENLIGHTENMENT)))
+			return 1;
+
 		hv->hv_tsc_emulation_control = data;
 		break;
 	case HV_X64_MSR_TSC_EMULATION_STATUS:
-		if (data && !host)
+		if (unlikely(!host && (!(hv_vcpu->cpuid_cache.features_eax &
+					HV_ACCESS_REENLIGHTENMENT) || data)))
 			return 1;
 
 		hv->hv_tsc_emulation_status = data;
@@ -1545,12 +1554,24 @@ static int kvm_hv_get_msr_pw(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata,
 		data = 0;
 		break;
 	case HV_X64_MSR_REENLIGHTENMENT_CONTROL:
+		if (unlikely(!host && !(hv_vcpu->cpuid_cache.features_eax &
+					HV_ACCESS_REENLIGHTENMENT)))
+			return 1;
+
 		data = hv->hv_reenlightenment_control;
 		break;
 	case HV_X64_MSR_TSC_EMULATION_CONTROL:
+		if (unlikely(!host && !(hv_vcpu->cpuid_cache.features_eax &
+					HV_ACCESS_REENLIGHTENMENT)))
+			return 1;
+
 		data = hv->hv_tsc_emulation_control;
 		break;
 	case HV_X64_MSR_TSC_EMULATION_STATUS:
+		if (unlikely(!host && !(hv_vcpu->cpuid_cache.features_eax &
+					HV_ACCESS_REENLIGHTENMENT)))
+			return 1;
+
 		data = hv->hv_tsc_emulation_status;
 		break;
 	case HV_X64_MSR_SYNDBG_OPTIONS:
-- 
2.30.2