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

Browse source

commit 5a15d83488 upstream.

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: fb3bd914b3 ("x86/srso: Add a Speculative RAS Overflow mitigation")
Reported-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Reported-by: Salvatore Bonaccorso <carnil@debian.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

...

This commit is contained in:

Borislav Petkov (AMD) 2023-08-07 10:46:04 +02:00 • committed by Greg Kroah-Hartman

parent 4974bd4b13

commit 9b73a2a43f

2 changed files with 15 additions and 11 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

19

arch/x86/kernel/cpu/amd.c

View file

7

arch/x86/kernel/cpu/bugs.c

View file