KVM: x86: Advertise SRSO_USER_KERNEL_NO to userspace

SRSO_USER_KERNEL_NO denotes whether the CPU is affected by SRSO across
user/kernel boundaries. Advertise it to guest userspace.

Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Link: https://lore.kernel.org/r/20241202120416.6054-3-bp@kernel.org

Author: bp3tk0v

arch/x86/kvm/cpuid.c

@@ -821,7 +821,7 @@ void kvm_set_cpu_caps(void)
 	kvm_cpu_cap_mask(CPUID_8000_0021_EAX,
 		F(NO_NESTED_DATA_BP) | F(LFENCE_RDTSC) | 0 /* SmmPgCfgLock */ |
 		F(NULL_SEL_CLR_BASE) | F(AUTOIBRS) | 0 /* PrefetchCtlMsr */ |
-		F(WRMSR_XX_BASE_NS)
+		F(WRMSR_XX_BASE_NS) | F(SRSO_USER_KERNEL_NO)
 	);
 
 	kvm_cpu_cap_check_and_set(X86_FEATURE_SBPB);