diff options
| author | Josh Poimboeuf <jpoimboe@kernel.org> | 2023-09-04 22:04:46 -0700 |
|---|---|---|
| committer | Borislav Petkov (AMD) <bp@alien8.de> | 2023-09-19 10:54:07 +0200 |
| commit | 91857ae20303cc98ed36720d9868fcd604a2ee75 (patch) | |
| tree | 2fc861b55386ff6c056c2301a571d6e59b5af1a0 /arch/x86/kernel/cpu/bugs.c | |
| parent | a8cf700c17d9ca6cb8ee7dc5c9330dbac3948237 (diff) | |
x86/srso: Set CPUID feature bits independently of bug or mitigation status
Booting with mitigations=off incorrectly prevents the
X86_FEATURE_{IBPB_BRTYPE,SBPB} CPUID bits from getting set.
Also, future CPUs without X86_BUG_SRSO might still have IBPB with branch
type prediction flushing, in which case SBPB should be used instead of
IBPB. The current code doesn't allow for that.
Also, cpu_has_ibpb_brtype_microcode() has some surprising side effects
and the setting of these feature bits really doesn't belong in the
mitigation code anyway. Move it to earlier.
Fixes: fb3bd914b3ec ("x86/srso: Add a Speculative RAS Overflow mitigation")
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Nikolay Borisov <nik.borisov@suse.com>
Reviewed-by: Borislav Petkov (AMD) <bp@alien8.de>
Acked-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/869a1709abfe13b673bdd10c2f4332ca253a40bc.1693889988.git.jpoimboe@kernel.org
Diffstat (limited to 'arch/x86/kernel/cpu/bugs.c')
| -rw-r--r-- | arch/x86/kernel/cpu/bugs.c | 13 |
1 files changed, 1 insertions, 12 deletions
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index bdd3e296f72b..b0ae985aa6a4 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -2404,27 +2404,16 @@ early_param("spec_rstack_overflow", srso_parse_cmdline); static void __init srso_select_mitigation(void) { - bool has_microcode; + bool has_microcode = boot_cpu_has(X86_FEATURE_IBPB_BRTYPE); if (!boot_cpu_has_bug(X86_BUG_SRSO) || cpu_mitigations_off()) goto pred_cmd; - /* - * The first check is for the kernel running as a guest in order - * for guests to verify whether IBPB is a viable mitigation. - */ - has_microcode = boot_cpu_has(X86_FEATURE_IBPB_BRTYPE) || cpu_has_ibpb_brtype_microcode(); if (!has_microcode) { pr_warn("IBPB-extending microcode not applied!\n"); pr_warn(SRSO_NOTICE); } else { /* - * Enable the synthetic (even if in a real CPUID leaf) - * flags for guests. - */ - setup_force_cpu_cap(X86_FEATURE_IBPB_BRTYPE); - - /* * Zen1/2 with SMT off aren't vulnerable after the right * IBPB microcode has been applied. */ |