linux-kernel - [PATCH RFC 07/22] KVM: x86: hyper-v: Honor HV_MSR_RESET

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Message-Id: <20210413122630.975617-8-vkuznets@redhat.com>
Date:   Tue, 13 Apr 2021 14:26:15 +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 07/22] KVM: x86: hyper-v: Honor HV_MSR_RESET_AVAILABLE privilege bit

HV_X64_MSR_RESET is only available to guest when HV_MSR_RESET_AVAILABLE bit
is exposed.

Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
---
 arch/x86/kvm/hyperv.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index 07f1fc8575e5..15d557ce32b5 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1289,6 +1289,10 @@ static int kvm_hv_set_msr_pw(struct kvm_vcpu *vcpu, u32 msr, u64 data,
 		}
 		break;
 	case HV_X64_MSR_RESET:
+		if (unlikely(!host && !(hv_vcpu->cpuid_cache.features_eax &
+					HV_MSR_RESET_AVAILABLE)))
+			return 1;
+
 		if (data == 1) {
 			vcpu_debug(vcpu, "hyper-v reset requested\n");
 			kvm_make_request(KVM_REQ_HV_RESET, vcpu);
@@ -1483,6 +1487,10 @@ static int kvm_hv_get_msr_pw(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata,
 	case HV_X64_MSR_CRASH_CTL:
 		return kvm_hv_msr_get_crash_ctl(kvm, pdata);
 	case HV_X64_MSR_RESET:
+		if (unlikely(!host && !(hv_vcpu->cpuid_cache.features_eax &
+					HV_MSR_RESET_AVAILABLE)))
+			return 1;
+
 		data = 0;
 		break;
 	case HV_X64_MSR_REENLIGHTENMENT_CONTROL:
-- 
2.30.2