linux-kernel - [PATCH 2/2] KVM: Expose AVX

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Message-Id: <20201216020129.19875-3-yang.zhong@intel.com>
Date:   Wed, 16 Dec 2020 10:01:29 +0800
From:   Yang Zhong <yang.zhong@...el.com>
To:     linux-kernel@...r.kernel.org, x86@...nel.org, kvm@...r.kernel.org
Cc:     tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, hpa@...or.com,
        tony.luck@...el.com, pbonzini@...hat.com, seanjc@...gle.com,
        vkuznets@...hat.com, wanpengli@...cent.com, jmattson@...gle.com,
        joro@...tes.org, kyung.min.park@...el.com, yang.zhong@...el.com
Subject: [PATCH 2/2] KVM: Expose AVX_VNNI instruction to guset

Expose AVX (VEX-encoded) versions of the Vector Neural Network
Instructions to guest.

The bit definition:
CPUID.(EAX=7,ECX=1):EAX[bit 4] AVX_VNNI

The following instructions are available when this feature is
present in the guest.
  1. VPDPBUS: Multiply and Add Unsigned and Signed Bytes
  2. VPDPBUSDS: Multiply and Add Unsigned and Signed Bytes with Saturation
  3. VPDPWSSD: Multiply and Add Signed Word Integers
  4. VPDPWSSDS: Multiply and Add Signed Integers with Saturation

This instruction is currently documented in the latest "extensions"
manual (ISE). It will appear in the "main" manual (SDM) in the future.

Signed-off-by: Yang Zhong <yang.zhong@...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 83637a2ff605..4229b67f0a8d 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -433,7 +433,7 @@ void kvm_set_cpu_caps(void)
 		kvm_cpu_cap_set(X86_FEATURE_SPEC_CTRL_SSBD);

 	kvm_cpu_cap_mask(CPUID_7_1_EAX,
-		F(AVX512_BF16)
+		F(AVX_VNNI) | F(AVX512_BF16)
 	);

 	kvm_cpu_cap_mask(CPUID_D_1_EAX,
-- 
2.29.2.334.gfaefdd61ec