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From:   Zeng Guang <guang.zeng@intel.com>
To:     Paolo Bonzini <pbonzini@redhat.com>,
        Sean Christopherson <seanjc@google.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>,
        H Peter Anvin <hpa@zytor.com>, kvm@vger.kernel.org
Cc:     x86@kernel.org, linux-kernel@vger.kernel.org,
        Zeng Guang <guang.zeng@intel.com>
Subject: [PATCH v2 8/8] KVM: x86: Advertise LASS CPUID to user space
Date:   Wed, 19 Jul 2023 10:45:58 +0800
Message-Id: <20230719024558.8539-9-guang.zeng@intel.com>
In-Reply-To: <20230719024558.8539-1-guang.zeng@intel.com>
References: <20230719024558.8539-1-guang.zeng@intel.com>
Precedence: bulk

Linear address space separation (LASS) is an independent mechanism
to enforce the mode-based protection that can prevent user-mode
accesses to supervisor-mode addresses, and vice versa. Because the
LASS protections are applied before paging, malicious software can
not acquire any paging-based timing information to compromise the
security of system.

The CPUID bit definition to support LASS:
CPUID.(EAX=07H.ECX=1):EAX.LASS[bit 6]

Advertise LASS to user space to support LASS virtualization.

Signed-off-by: Zeng Guang <guang.zeng@intel.com>
Tested-by: Xuelian Guo <xuelian.guo@intel.com>
---
 arch/x86/kvm/cpuid.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 0c9660a07b23..a7fafe99ffe4 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -646,9 +646,8 @@ void kvm_set_cpu_caps(void)
 		kvm_cpu_cap_set(X86_FEATURE_SPEC_CTRL_SSBD);
 
 	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(AVX_VNNI) | F(AVX512_BF16) | F(LASS) | F(CMPCCXADD) |
+		F(FZRM) | F(FSRS) | F(FSRC) | F(AMX_FP16) | F(AVX_IFMA)
 	);
 
 	kvm_cpu_cap_init_kvm_defined(CPUID_7_1_EDX,
-- 
2.27.0