linux-kernel - [PATCH] KVM: VMX: support MSR_IA32_ARCH

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Date:   Mon, 25 Jun 2018 14:04:37 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     robert.hu@...ux.intel.com
Subject: [PATCH] KVM: VMX: support MSR_IA32_ARCH_CAPABILITIES as a feature MSR

This lets userspace read the MSR_IA32_ARCH_CAPABILITIES and check that all
requested features are available on the host.

Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kvm/x86.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index c88ed554bb66..a029f9fca993 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1097,6 +1097,7 @@ bool kvm_rdpmc(struct kvm_vcpu *vcpu)
 
 	MSR_F10H_DECFG,
 	MSR_IA32_UCODE_REV,
+	MSR_IA32_ARCH_CAPABILITIES,
 };
 
 static unsigned int num_msr_based_features;
@@ -1105,7 +1106,8 @@ static int kvm_get_msr_feature(struct kvm_msr_entry *msr)
 {
 	switch (msr->index) {
 	case MSR_IA32_UCODE_REV:
-		rdmsrl(msr->index, msr->data);
+	case MSR_IA32_ARCH_CAPABILITIES:
+		rdmsrl_safe(msr->index, &msr->data);
 		break;
 	default:
 		if (kvm_x86_ops->get_msr_feature(msr))
-- 
1.8.3.1