linux-kernel - [PATCH v3 5/7] x86/cpu, kvm: Define a scattered AMD Automatic IBRS feature bit

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Date:   Tue, 29 Nov 2022 17:58:14 -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 5/7] x86/cpu, kvm: Define a scattered AMD Automatic IBRS feature bit

It's a part of the CPUID 0x80000021 leaf, and this allows us to
group this and other CPUID 0x80000021 EAX feature bits to being
propagated via kvm_set_cpu_caps instead of open-coding them in
__do_cpuid_func().

Signed-off-by: Kim Phillips <kim.phillips@....com>
---
 arch/x86/include/asm/cpufeatures.h | 1 +
 arch/x86/kernel/cpu/scattered.c    | 1 +
 2 files changed, 2 insertions(+)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 5ddde18c1ae8..961eb49532b7 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -309,6 +309,7 @@
 #define X86_FEATURE_MSR_TSX_CTRL	(11*32+20) /* "" MSR IA32_TSX_CTRL (Intel) implemented */
 #define X86_FEATURE_NO_NESTED_DATA_BP	(11*32+21) /* "" AMD No Nested Data Breakpoints */
 #define X86_FEATURE_NULL_SEL_CLR_BASE	(11*32+22) /* "" AMD Null Selector Clears Base */
+#define X86_FEATURE_AUTOIBRS		(11*32+23) /* AMD Automatic IBRS */
 
 /* Intel-defined CPU features, CPUID level 0x00000007:1 (EAX), word 12 */
 #define X86_FEATURE_AVX_VNNI		(12*32+ 4) /* AVX VNNI instructions */
diff --git a/arch/x86/kernel/cpu/scattered.c b/arch/x86/kernel/cpu/scattered.c
index caa03466cd9e..7ae7203cd410 100644
--- a/arch/x86/kernel/cpu/scattered.c
+++ b/arch/x86/kernel/cpu/scattered.c
@@ -48,6 +48,7 @@ static const struct cpuid_bit cpuid_bits[] = {
 	{ X86_FEATURE_NO_NESTED_DATA_BP,CPUID_EAX,  0, 0x80000021, 0 },
 	{ X86_FEATURE_LFENCE_RDTSC,	CPUID_EAX,  2, 0x80000021, 0 },
 	{ X86_FEATURE_NULL_SEL_CLR_BASE,CPUID_EAX,  6, 0x80000021, 0 },
+	{ X86_FEATURE_AUTOIBRS,		CPUID_EAX,  8, 0x80000021, 0 },
 	{ X86_FEATURE_PERFMON_V2,	CPUID_EAX,  0, 0x80000022, 0 },
 	{ X86_FEATURE_AMD_LBR_V2,	CPUID_EAX,  1, 0x80000022, 0 },
 	{ 0, 0, 0, 0, 0 }
-- 
2.34.1