linux-kernel - [PATCH v3 3/4] KVM: SVM: Add support for SVM instruction address check change

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Message-Id: <20210126081831.570253-4-wei.huang2@amd.com>
Date:   Tue, 26 Jan 2021 03:18:30 -0500
From:   Wei Huang <wei.huang2@....com>
To:     kvm@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, pbonzini@...hat.com,
        vkuznets@...hat.com, mlevitsk@...hat.com, seanjc@...gle.com,
        joro@...tes.org, bp@...en8.de, tglx@...utronix.de,
        mingo@...hat.com, x86@...nel.org, jmattson@...gle.com,
        wanpengli@...cent.com, bsd@...hat.com, dgilbert@...hat.com,
        luto@...capital.net, wei.huang2@....com
Subject: [PATCH v3 3/4] KVM: SVM: Add support for SVM instruction address check change

New AMD CPUs have a change that checks #VMEXIT intercept on special SVM
instructions before checking their EAX against reserved memory region.
This change is indicated by CPUID_0x8000000A_EDX[28]. If it is 1, #VMEXIT
is triggered before #GP. KVM doesn't need to intercept and emulate #GP
faults as #GP is supposed to be triggered.

Co-developed-by: Bandan Das <bsd@...hat.com>
Signed-off-by: Bandan Das <bsd@...hat.com>
Signed-off-by: Wei Huang <wei.huang2@....com>
Reviewed-by: Maxim Levitsky <mlevitsk@...hat.com>
---
 arch/x86/include/asm/cpufeatures.h | 1 +
 arch/x86/kvm/svm/svm.c             | 3 +++
 2 files changed, 4 insertions(+)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 84b887825f12..ea89d6fdd79a 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -337,6 +337,7 @@
 #define X86_FEATURE_AVIC		(15*32+13) /* Virtual Interrupt Controller */
 #define X86_FEATURE_V_VMSAVE_VMLOAD	(15*32+15) /* Virtual VMSAVE VMLOAD */
 #define X86_FEATURE_VGIF		(15*32+16) /* Virtual GIF */
+#define X86_FEATURE_SVME_ADDR_CHK	(15*32+28) /* "" SVME addr check */
 
 /* Intel-defined CPU features, CPUID level 0x00000007:0 (ECX), word 16 */
 #define X86_FEATURE_AVX512VBMI		(16*32+ 1) /* AVX512 Vector Bit Manipulation instructions*/
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index e5ca01e25e89..f9233c79265b 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -1036,6 +1036,9 @@ static __init int svm_hardware_setup(void)
 		}
 	}
 
+	if (boot_cpu_has(X86_FEATURE_SVME_ADDR_CHK))
+		svm_gp_erratum_intercept = false;
+
 	if (vgif) {
 		if (!boot_cpu_has(X86_FEATURE_VGIF))
 			vgif = false;
-- 
2.27.0