linux-kernel - [PATCH 6/6] x86: KVM: Enable PREFETCHIT0/1 CPUID and expose it to guest

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Message-Id: <20221019084734.3590760-7-jiaxi.chen@linux.intel.com>
Date:   Wed, 19 Oct 2022 16:47:34 +0800
From:   Jiaxi Chen <jiaxi.chen@...ux.intel.com>
To:     kvm@...r.kernel.org
Cc:     tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com,
        seanjc@...gle.com, pbonzini@...hat.com, ndesaulniers@...gle.com,
        alexandre.belloni@...tlin.com, peterz@...radead.org,
        jiaxi.chen@...ux.intel.com, jpoimboe@...nel.org,
        chang.seok.bae@...el.com, pawan.kumar.gupta@...ux.intel.com,
        babu.moger@....com, jmattson@...gle.com, sandipan.das@....com,
        tony.luck@...el.com, sathyanarayanan.kuppuswamy@...ux.intel.com,
        fenghua.yu@...el.com, keescook@...omium.org,
        jane.malalane@...rix.com, nathan@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH 6/6] x86: KVM: Enable PREFETCHIT0/1 CPUID and expose it to guest

Latest Intel platform Granite Rapids has introduced a new instruction -
PREFETCHIT0/1, which moves code to memory (cache) closer to the processor
depending on specific hints.

The bit definition:
CPUID.(EAX=7,ECX=1):EDX[bit 14]

This patch enables this CPUID in the kernel feature bits and expose it
to guest OS.

Signed-off-by: Jiaxi Chen <jiaxi.chen@...ux.intel.com>
---
 arch/x86/include/asm/cpufeatures.h | 1 +
 arch/x86/kvm/cpuid.c               | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/cpufeatures.h b/arch/x86/include/asm/cpufeatures.h
index 4e0bbffedbb4..de8aa62bbdb1 100644
--- a/arch/x86/include/asm/cpufeatures.h
+++ b/arch/x86/include/asm/cpufeatures.h
@@ -426,6 +426,7 @@
 /* Intel-defined CPU features, CPUID level 0x00000007:1 (EDX), word 20 */
 #define X86_FEATURE_AVX_VNNI_INT8       (20*32+ 4) /* Support for VPDPB[SU,UU,SS]D[,S] */
 #define X86_FEATURE_AVX_NE_CONVERT      (20*32+ 5) /* AVX NE CONVERT Instructions */
+#define X86_FEATURE_PREFETCHITI         (20*32+14) /* PREFETCHIT0/1 Instructions */
 
 /*
  * BUG word(s)
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index fcd00c68e546..e73307732d10 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -661,7 +661,7 @@ void kvm_set_cpu_caps(void)
 		F(AVX_IFMA));
 
 	kvm_cpu_cap_mask(CPUID_7_1_EDX,
-		F(AVX_VNNI_INT8) | F(AVX_NE_CONVERT)
+		F(AVX_VNNI_INT8) | F(AVX_NE_CONVERT) | F(PREFETCHITI)
 	);
 
 	kvm_cpu_cap_mask(CPUID_D_1_EAX,
-- 
2.27.0