diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2022-07-18 14:41:37 +0300 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2022-07-18 16:38:09 +0300 |
| commit | 28a99e95f55c61855983d36a88c05c178d966bb7 (patch) | |
| tree | 38be23a964f0ead645743a976f7c61e0b5846989 /arch/x86/kernel | |
| parent | ff6992735ade75aae3e35d16b17da1008d753d28 (diff) | |
| download | linux-28a99e95f55c61855983d36a88c05c178d966bb7.tar.xz | |
x86/amd: Use IBPB for firmware calls
On AMD IBRS does not prevent Retbleed; as such use IBPB before a
firmware call to flush the branch history state.
And because in order to do an EFI call, the kernel maps a whole lot of
the kernel page table into the EFI page table, do an IBPB just in case
in order to prevent the scenario of poisoning the BTB and causing an EFI
call using the unprotected RET there.
[ bp: Massage. ]
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/20220715194550.793957-1-cascardo@canonical.com
Diffstat (limited to 'arch/x86/kernel')
| -rw-r--r-- | arch/x86/kernel/cpu/bugs.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index aa34f908c39f..78c9082242a9 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1516,7 +1516,16 @@ static void __init spectre_v2_select_mitigation(void) * the CPU supports Enhanced IBRS, kernel might un-intentionally not * enable IBRS around firmware calls. */ - if (boot_cpu_has(X86_FEATURE_IBRS) && !spectre_v2_in_ibrs_mode(mode)) { + if (boot_cpu_has_bug(X86_BUG_RETBLEED) && + (boot_cpu_data.x86_vendor == X86_VENDOR_AMD || + boot_cpu_data.x86_vendor == X86_VENDOR_HYGON)) { + + if (retbleed_cmd != RETBLEED_CMD_IBPB) { + setup_force_cpu_cap(X86_FEATURE_USE_IBPB_FW); + pr_info("Enabling Speculation Barrier for firmware calls\n"); + } + + } else if (boot_cpu_has(X86_FEATURE_IBRS) && !spectre_v2_in_ibrs_mode(mode)) { setup_force_cpu_cap(X86_FEATURE_USE_IBRS_FW); pr_info("Enabling Restricted Speculation for firmware calls\n"); } |