diff options
| author | Borislav Petkov (AMD) <bp@alien8.de> | 2023-08-07 10:46:04 +0200 |
|---|---|---|
| committer | Borislav Petkov (AMD) <bp@alien8.de> | 2023-08-07 10:53:08 +0200 |
| commit | 5a15d8348881e9371afdf9f5357a135489496955 (patch) | |
| tree | 477c10789c4ac4d317cc375926e6eda917baf0d3 /arch/x86/kernel/cpu/bugs.c | |
| parent | 3bbbe97ad83db8d9df06daf027b0840188de625d (diff) | |
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 <konrad.wilk@oracle.com>
Reported-by: Salvatore Bonaccorso <carnil@debian.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Diffstat (limited to 'arch/x86/kernel/cpu/bugs.c')
| -rw-r--r-- | arch/x86/kernel/cpu/bugs.c | 7 |
1 files changed, 3 insertions, 4 deletions
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 7314a6bdc862b..2afe69bff2189 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -2265,14 +2265,13 @@ static void __init srso_select_mitigation(void) * flags for guests. */ setup_force_cpu_cap(X86_FEATURE_IBPB_BRTYPE); - setup_force_cpu_cap(X86_FEATURE_SBPB); /* * Zen1/2 with SMT off aren't vulnerable after the right * IBPB microcode has been applied. */ if ((boot_cpu_data.x86 < 0x19) && - (cpu_smt_control == CPU_SMT_DISABLED)) + (!cpu_smt_possible() || (cpu_smt_control == CPU_SMT_DISABLED))) setup_force_cpu_cap(X86_FEATURE_SRSO_NO); } @@ -2345,8 +2344,8 @@ static void __init srso_select_mitigation(void) pr_info("%s%s\n", srso_strings[srso_mitigation], (has_microcode ? "" : ", no microcode")); pred_cmd: - if (boot_cpu_has(X86_FEATURE_SRSO_NO) || - srso_cmd == SRSO_CMD_OFF) + if ((boot_cpu_has(X86_FEATURE_SRSO_NO) || srso_cmd == SRSO_CMD_OFF) && + boot_cpu_has(X86_FEATURE_SBPB)) x86_pred_cmd = PRED_CMD_SBPB; } |