6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Johannes Wikner kwikner@ethz.ch
commit 3ea87dfa31a7b0bb0ff1675e67b9e54883013074 upstream.
Set this flag if the CPU has an IBPB implementation that does not invalidate return target predictions. Zen generations < 4 do not flush the RSB when executing an IBPB and this bug flag denotes that.
[ bp: Massage. ]
Signed-off-by: Johannes Wikner kwikner@ethz.ch Signed-off-by: Borislav Petkov (AMD) bp@alien8.de Cc: stable@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/include/asm/cpufeatures.h | 1 + arch/x86/kernel/cpu/common.c | 3 +++ 2 files changed, 4 insertions(+)
--- a/arch/x86/include/asm/cpufeatures.h +++ b/arch/x86/include/asm/cpufeatures.h @@ -517,4 +517,5 @@ #define X86_BUG_DIV0 X86_BUG(1*32 + 1) /* AMD DIV0 speculation bug */ #define X86_BUG_RFDS X86_BUG(1*32 + 2) /* CPU is vulnerable to Register File Data Sampling */ #define X86_BUG_BHI X86_BUG(1*32 + 3) /* CPU is affected by Branch History Injection */ +#define X86_BUG_IBPB_NO_RET X86_BUG(1*32 + 4) /* "ibpb_no_ret" IBPB omits return target predictions */ #endif /* _ASM_X86_CPUFEATURES_H */ --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1483,6 +1483,9 @@ static void __init cpu_set_bug_bits(stru boot_cpu_has(X86_FEATURE_HYPERVISOR))) setup_force_cpu_bug(X86_BUG_BHI);
+ if (cpu_has(c, X86_FEATURE_AMD_IBPB) && !cpu_has(c, X86_FEATURE_AMD_IBPB_RET)) + setup_force_cpu_bug(X86_BUG_IBPB_NO_RET); + if (cpu_matches(cpu_vuln_whitelist, NO_MELTDOWN)) return;