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authorLinus Torvalds <torvalds@linux-foundation.org>2022-08-13 14:24:12 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2022-08-13 14:24:12 -0700
commitc5f1e32e323157c71eacc6fe087db8d586ff6cb5 (patch)
treea4a74b1e8fec09e91ba8910aba117389a466ce82 /arch
parent04734361953b8cc30d5552c1abe907ccfc8bc0fa (diff)
parente6cfcdda8cbe81eaf821c897369a65fec987b404 (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.c10
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],

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