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* [PATCH] KVM: VMX: expose the host's ARCH_CAPABILITIES MSR to userspace
@ 2018-02-24  0:52 Paolo Bonzini
  2018-02-26 22:13 ` Konrad Rzeszutek Wilk
  0 siblings, 1 reply; 10+ messages in thread
From: Paolo Bonzini @ 2018-02-24  0:52 UTC (permalink / raw)
  To: linux-kernel, kvm; +Cc: David Woodhouse, KarimAllah Ahmed

Use the new MSR feature framework to expose the ARCH_CAPABILITIES MSR to
userspace.  This way, userspace can access the capabilities even if it
does not have the permissions to read MSRs.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 arch/x86/kvm/vmx.c | 12 +++++++++++-
 arch/x86/kvm/x86.c |  1 +
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 130fca0ea1bf..99689061e11e 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -3228,7 +3228,17 @@ static inline bool vmx_feature_control_msr_valid(struct kvm_vcpu *vcpu,
 
 static int vmx_get_msr_feature(struct kvm_msr_entry *msr)
 {
-	return 1;
+	switch (msr->index) {
+	case MSR_IA32_ARCH_CAPABILITIES:
+		if (!boot_cpu_has(X86_FEATURE_ARCH_CAPABILITIES))
+			return 1;
+		rdmsrl(msr->index, msr->data);
+		break;
+	default:
+		return 1;
+	}
+
+	return 0;
 }
 
 /*
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 54b4ed55945b..e9a8cc9e3b2b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1054,6 +1054,7 @@ bool kvm_rdpmc(struct kvm_vcpu *vcpu)
  * can be used by a hypervisor to validate requested CPU features.
  */
 static u32 msr_based_features[] = {
+	MSR_IA32_ARCH_CAPABILITIES,
 	MSR_F10H_DECFG,
 };
 
-- 
1.8.3.1

^ permalink raw reply related	[flat|nested] 10+ messages in thread

end of thread, other threads:[~2018-03-07 15:40 UTC | newest]

Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-02-24  0:52 [PATCH] KVM: VMX: expose the host's ARCH_CAPABILITIES MSR to userspace Paolo Bonzini
2018-02-26 22:13 ` Konrad Rzeszutek Wilk
2018-02-26 22:23   ` Konrad Rzeszutek Wilk
2018-03-01 21:39   ` Radim Krčmář
2018-03-02  9:36     ` Paolo Bonzini
2018-03-02 21:42       ` Radim Krčmář
2018-03-07 11:53         ` Paolo Bonzini
2018-03-07 14:56           ` Radim Krčmář
2018-03-07 15:10             ` Paolo Bonzini
2018-03-07 15:39               ` Radim Krčmář

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