linux-kernel - [PATCH 1/2] x86/cpufeatures: Add the Virtual SPEC

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Message-ID: <160738067105.28590.10158084163761735153.stgit@bmoger-ubuntu>
Date:   Mon, 07 Dec 2020 16:37:51 -0600
From:   Babu Moger <babu.moger@....com>
To:     pbonzini@...hat.com, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de
Cc:     fenghua.yu@...el.com, tony.luck@...el.com, wanpengli@...cent.com,
        kvm@...r.kernel.org, thomas.lendacky@....com, peterz@...radead.org,
        seanjc@...gle.com, joro@...tes.org, x86@...nel.org,
        kyung.min.park@...el.com, linux-kernel@...r.kernel.org,
        krish.sadhukhan@...cle.com, hpa@...or.com, mgross@...ux.intel.com,
        vkuznets@...hat.com, kim.phillips@....com, wei.huang2@....com,
        jmattson@...gle.com
Subject: [PATCH 1/2] x86/cpufeatures: Add the Virtual SPEC_CTRL feature

Newer AMD processors have a feature to virtualize the use of the SPEC_CTRL
MSR. This feature is identified via CPUID 0x8000000A_EDX[20]. When present,
the SPEC_CTRL MSR is automatically virtualized and no longer requires
hypervisor intervention.

Signed-off-by: Babu Moger <babu.moger@....com>
---
 arch/x86/include/asm/cpufeatures.h |    1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index dad350d42ecf..d649ac5ed7c7 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -335,6 +335,7 @@
 #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_V_SPEC_CTRL		(15*32+20) /* Virtual SPEC_CTRL */
 
 /* Intel-defined CPU features, CPUID level 0x00000007:0 (ECX), word 16 */
 #define X86_FEATURE_AVX512VBMI		(16*32+ 1) /* AVX512 Vector Bit Manipulation instructions*/