linux-kernel - [PATCH v3 7/7] x86/cpu, kvm: Propagate the AMD Automatic IBRS feature to the guest

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Date:   Tue, 29 Nov 2022 17:58:16 -0600
From:   Kim Phillips <kim.phillips@....com>
To:     <x86@...nel.org>
CC:     Kim Phillips <kim.phillips@....com>,
        Babu Moger <Babu.Moger@....com>,
        Borislav Petkov <bp@...en8.de>, Borislav Petkov <bp@...e.de>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...hat.com>,
        Joao Martins <joao.m.martins@...cle.com>,
        Jonathan Corbet <corbet@....net>,
        "Konrad Rzeszutek Wilk" <konrad.wilk@...cle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        David Woodhouse <dwmw@...zon.co.uk>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Juergen Gross <jgross@...e.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Tony Luck <tony.luck@...el.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        Alexey Kardashevskiy <aik@....com>, <kvm@...r.kernel.org>,
        <linux-doc@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH v3 7/7] x86/cpu, kvm: Propagate the AMD Automatic IBRS feature to the guest

Add the AMD Automatic IBRS feature bit to those being
propagated to the guest.

Signed-off-by: Kim Phillips <kim.phillips@....com>
---
 arch/x86/kvm/cpuid.c         | 2 +-
 arch/x86/kvm/reverse_cpuid.h | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 8e37760cea1b..acda3883a905 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -743,7 +743,7 @@ void kvm_set_cpu_caps(void)
 	 */
 	kvm_cpu_cap_init_scattered(CPUID_8000_0021_EAX,
 				   SF(NO_NESTED_DATA_BP) | SF(LFENCE_RDTSC) |
-				   SF(NULL_SEL_CLR_BASE));
+				   SF(NULL_SEL_CLR_BASE) | SF(AUTOIBRS));
 	if (cpu_feature_enabled(X86_FEATURE_LFENCE_RDTSC))
 		kvm_cpu_cap_set(X86_FEATURE_LFENCE_RDTSC);
 	if (!static_cpu_has_bug(X86_BUG_NULL_SEG))
diff --git a/arch/x86/kvm/reverse_cpuid.h b/arch/x86/kvm/reverse_cpuid.h
index 184614e27d5b..0bf02c02bb0a 100644
--- a/arch/x86/kvm/reverse_cpuid.h
+++ b/arch/x86/kvm/reverse_cpuid.h
@@ -30,6 +30,7 @@ enum kvm_only_cpuid_leafs {
 #define KVM_X86_FEATURE_NO_NESTED_DATA_BP	KVM_X86_FEATURE(CPUID_8000_0021_EAX, 0)
 #define KVM_X86_FEATURE_LFENCE_RDTSC		KVM_X86_FEATURE(CPUID_8000_0021_EAX, 2)
 #define KVM_X86_FEATURE_NULL_SEL_CLR_BASE	KVM_X86_FEATURE(CPUID_8000_0021_EAX, 6)
+#define KVM_X86_FEATURE_AUTOIBRS		KVM_X86_FEATURE(CPUID_8000_0021_EAX, 8)
 
 struct cpuid_reg {
 	u32 function;
@@ -89,6 +90,7 @@ static __always_inline u32 __feature_translate(int x86_feature)
 	case X86_FEATURE_NO_NESTED_DATA_BP:	return KVM_X86_FEATURE_NO_NESTED_DATA_BP;
 	case X86_FEATURE_LFENCE_RDTSC:		return KVM_X86_FEATURE_LFENCE_RDTSC;
 	case X86_FEATURE_NULL_SEL_CLR_BASE:	return KVM_X86_FEATURE_NULL_SEL_CLR_BASE;
+	case X86_FEATURE_AUTOIBRS:		return KVM_X86_FEATURE_AUTOIBRS;
 	default: break;
 	}
 
-- 
2.34.1