linux-kernel - [PATCH v10 9/9] KVM: x86: Expose LAM feature to userspace VMM

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Message-Id: <20230719144131.29052-10-binbin.wu@linux.intel.com>
Date:   Wed, 19 Jul 2023 22:41:31 +0800
From:   Binbin Wu <binbin.wu@...ux.intel.com>
To:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     seanjc@...gle.com, pbonzini@...hat.com, chao.gao@...el.com,
        kai.huang@...el.com, David.Laight@...LAB.COM,
        robert.hu@...ux.intel.com, guang.zeng@...el.com,
        binbin.wu@...ux.intel.com
Subject: [PATCH v10 9/9] KVM: x86: Expose LAM feature to userspace VMM

From: Robert Hoo <robert.hu@...ux.intel.com>

LAM feature is enumerated by CPUID.7.1:EAX.LAM[bit 26].
Expose the feature to userspace as the final step after the following
supports:
- CR4.LAM_SUP virtualization
- CR3.LAM_U48 and CR3.LAM_U57 virtualization
- Check and untag 64-bit linear address when LAM applies in instruction
  emulations and VMExit handlers.

Exposing SGX LAM support is not supported yet. SGX LAM support is enumerated
in SGX's own CPUID and there's no hard requirement that it must be supported
when LAM is reported in CPUID leaf 0x7.

Signed-off-by: Robert Hoo <robert.hu@...ux.intel.com>
Signed-off-by: Binbin Wu <binbin.wu@...ux.intel.com>
Reviewed-by: Jingqi Liu <jingqi.liu@...el.com>
Reviewed-by: Chao Gao <chao.gao@...el.com>
Reviewed-by: Kai Huang <kai.huang@...el.com>
Tested-by: Xuelian Guo <xuelian.guo@...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 7ebf3ce1bb5f..21d525b01d45 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -645,7 +645,7 @@ void kvm_set_cpu_caps(void)
 	kvm_cpu_cap_mask(CPUID_7_1_EAX,
 		F(AVX_VNNI) | F(AVX512_BF16) | F(CMPCCXADD) |
 		F(FZRM) | F(FSRS) | F(FSRC) |
-		F(AMX_FP16) | F(AVX_IFMA)
+		F(AMX_FP16) | F(AVX_IFMA) | F(LAM)
 	);
 
 	kvm_cpu_cap_init_kvm_defined(CPUID_7_1_EDX,
-- 
2.25.1