x86/srso: Tie SBPB bit setting to microcode patch detection

The SBPB bit in MSR_IA32_PRED_CMD is supported only after a microcode
patch has been applied so set X86_FEATURE_SBPB only then. Otherwise,
guests would attempt to set that bit and #GP on the MSR write.

While at it, make SMT detection more robust as some guests - depending
on how and what CPUID leafs their report - lead to cpu_smt_control
getting set to CPU_SMT_NOT_SUPPORTED but SRSO_NO should be set for any
guest incarnation where one simply cannot do SMT, for whatever reason.

Fixes: fb3bd914b3ec ("x86/srso: Add a Speculative RAS Overflow mitigation")
Reported-by: Konrad Rzeszutek Wilk <[email protected]>
Reported-by: Salvatore Bonaccorso <[email protected]>
Signed-off-by: Borislav Petkov (AMD) <[email protected]>

0 files changed, 0 insertions, 0 deletions