From: Xin Li <xin3.li@xxxxxxxxx> Allow FRED/LKGS to be advertised to guests after changes required to enable FRED in a KVM guest are in place. LKGS is introduced with FRED to completely eliminate the need to swapgs explicilty, because 1) FRED transitions ensure that an operating system can always operate with its own GS base address. 2) LKGS behaves like the MOV to GS instruction except that it loads the base address into the IA32_KERNEL_GS_BASE MSR instead of the GS segment’s descriptor cache, which is exactly what Linux kernel does to load a user level GS base. Thus there is no need to SWAPGS away from the kernel GS base and an execution of SWAPGS causes #UD if FRED transitions are enabled. A FRED CPU must enumerate LKGS. When LKGS is not available, FRED must not be enabled. 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 41786b834b16..c55d150ece8d 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -699,7 +699,7 @@ 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(FZRM) | F(FSRS) | F(FSRC) | F(FRED) | F(LKGS) | F(AMX_FP16) | F(AVX_IFMA) | F(LAM) ); -- 2.46.2
