linux-kernel - [PATCH v11 16/16] KVM: x86: Advertise LASS CPUID to user space

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20230913124227.12574-17-binbin.wu@linux.intel.com>
Date:   Wed, 13 Sep 2023 20:42:27 +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 v11 16/16] KVM: x86: Advertise LASS CPUID to user space

From: Zeng Guang <guang.zeng@...el.com>

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.

Note: KVM LASS feature exposure also depends on cpuid capability
held by host kernel. It will be masked to guest if host vsyscall
is in emulate mode which actually disables LASS.

Signed-off-by: Zeng Guang <guang.zeng@...el.com>
Signed-off-by: Binbin Wu <binbin.wu@...ux.intel.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 a0db266bab73..81a52218c20f 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -675,7 +675,7 @@ void kvm_set_cpu_caps(void)
 		kvm_cpu_cap_set(X86_FEATURE_SPEC_CTRL_SSBD);

 	kvm_cpu_cap_mask(CPUID_7_1_EAX,
-		F(AVX_VNNI) | F(AVX512_BF16) | F(CMPCCXADD) |
+		F(AVX_VNNI) | F(AVX512_BF16) | F(LASS) | F(CMPCCXADD) |
 		F(FZRM) | F(FSRS) | F(FSRC) |
 		F(AMX_FP16) | F(AVX_IFMA) | F(LAM)
 	);
-- 
2.25.1