[PATCH v3 20/27] KVM: x86: Allow WRMSRNS to be advertised to guests

From: Xin Li (Intel)
Date: Tue Oct 01 2024 - 01:08:23 EST


From: Xin Li <xin3.li@xxxxxxxxx>

Allow WRMSRNS to be advertised to guests.

WRMSRNS behaves exactly like WRMSR with the only difference being
that it is not a serializing instruction by default. It improves
performance when being used in a hot path, e.g., setting FRED RSP0.

Signed-off-by: Xin Li <xin3.li@xxxxxxxxx>
Signed-off-by: Xin Li (Intel) <xin@xxxxxxxxx>
Tested-by: Shan Kang <shan.kang@xxxxxxxxx>
---
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 c55d150ece8d..63a78ebf9482 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -700,7 +700,7 @@ 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(FRED) | F(LKGS) |
- F(AMX_FP16) | F(AVX_IFMA) | F(LAM)
+ F(WRMSRNS) | F(AMX_FP16) | F(AVX_IFMA) | F(LAM)
);

kvm_cpu_cap_init_kvm_defined(CPUID_7_1_EDX,
--
2.46.2