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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2022-08-13 14:24:12 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2022-08-13 14:24:12 -0700 |
| commit | c5f1e32e323157c71eacc6fe087db8d586ff6cb5 (patch) | |
| tree | a4a74b1e8fec09e91ba8910aba117389a466ce82 /arch | |
| parent | 04734361953b8cc30d5552c1abe907ccfc8bc0fa (diff) | |
| parent | e6cfcdda8cbe81eaf821c897369a65fec987b404 (diff) | |
Merge tag 'x86-urgent-2022-08-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull x86 fix from Ingo Molnar:
"Fix the 'IBPB mitigated RETBleed' mode of operation on AMD CPUs (not
turned on by default), which also need STIBP enabled (if available) to
be '100% safe' on even the shortest speculation windows"
* tag 'x86-urgent-2022-08-13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/bugs: Enable STIBP for IBPB mitigated RETBleed
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kernel/cpu/bugs.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 9f7e751b91df..510d85261132 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -152,7 +152,7 @@ void __init check_bugs(void) /* * spectre_v2_user_select_mitigation() relies on the state set by * retbleed_select_mitigation(); specifically the STIBP selection is - * forced for UNRET. + * forced for UNRET or IBPB. */ spectre_v2_user_select_mitigation(); ssb_select_mitigation(); @@ -1179,7 +1179,8 @@ spectre_v2_user_select_mitigation(void) boot_cpu_has(X86_FEATURE_AMD_STIBP_ALWAYS_ON)) mode = SPECTRE_V2_USER_STRICT_PREFERRED; - if (retbleed_mitigation == RETBLEED_MITIGATION_UNRET) { + if (retbleed_mitigation == RETBLEED_MITIGATION_UNRET || + retbleed_mitigation == RETBLEED_MITIGATION_IBPB) { if (mode != SPECTRE_V2_USER_STRICT && mode != SPECTRE_V2_USER_STRICT_PREFERRED) pr_info("Selecting STIBP always-on mode to complement retbleed mitigation\n"); @@ -2360,10 +2361,11 @@ static ssize_t srbds_show_state(char *buf) static ssize_t retbleed_show_state(char *buf) { - if (retbleed_mitigation == RETBLEED_MITIGATION_UNRET) { + if (retbleed_mitigation == RETBLEED_MITIGATION_UNRET || + retbleed_mitigation == RETBLEED_MITIGATION_IBPB) { if (boot_cpu_data.x86_vendor != X86_VENDOR_AMD && boot_cpu_data.x86_vendor != X86_VENDOR_HYGON) - return sprintf(buf, "Vulnerable: untrained return thunk on non-Zen uarch\n"); + return sprintf(buf, "Vulnerable: untrained return thunk / IBPB on non-AMD based uarch\n"); return sprintf(buf, "%s; SMT %s\n", retbleed_strings[retbleed_mitigation], |