linux-kernel - [PATCH 2/2] x86: Expose AVX512

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Date:   Mon,  7 Dec 2020 19:34:41 -0800
From:   Kyung Min Park <kyung.min.park@...el.com>
To:     x86@...nel.org, linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, hpa@...or.com,
        pbonzini@...hat.com, sean.j.christopherson@...el.com,
        jmattson@...gle.com, joro@...tes.org, vkuznets@...hat.com,
        wanpengli@...cent.com, kyung.min.park@...el.com,
        cathy.zhang@...el.com
Subject: [PATCH 2/2] x86: Expose AVX512_FP16 for supported CPUID

From: Cathy Zhang <cathy.zhang@...el.com>

AVX512_FP16 is supported by Intel processors, like Sapphire Rapids.
It could gain better performance for it's faster compared to FP32
while meets the precision or magnitude requirement. It's availability
is indicated by CPUID.(EAX=7,ECX=0):EDX[bit 23].

Expose it in KVM supported CPUID, then guest could make use of it.

Signed-off-by: Cathy Zhang <cathy.zhang@...el.com>
Signed-off-by: Kyung Min Park <kyung.min.park@...el.com>
Acked-by: Dave Hansen <dave.hansen@...el.com>
Reviewed-by: Tony Luck <tony.luck@...el.com>
---
 arch/x86/kvm/cpuid.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index e83bfe2daf82..d7707cfc9401 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -416,7 +416,7 @@ void kvm_set_cpu_caps(void)
 		F(AVX512_4VNNIW) | F(AVX512_4FMAPS) | F(SPEC_CTRL) |
 		F(SPEC_CTRL_SSBD) | F(ARCH_CAPABILITIES) | F(INTEL_STIBP) |
 		F(MD_CLEAR) | F(AVX512_VP2INTERSECT) | F(FSRM) |
-		F(SERIALIZE) | F(TSXLDTRK)
+		F(SERIALIZE) | F(TSXLDTRK) | F(AVX512_FP16)
 	);
 
 	/* TSC_ADJUST and ARCH_CAPABILITIES are emulated in software. */
-- 
2.17.1