eIBRS protects against RSB underflow/poisoning attacks. Adding
retpoline to the mix doesn't change that. Retpoline has a balanced
CALL/RET anyway.
So the current full RSB filling on VMEXIT with eIBRS+retpoline is
overkill. Disable it (or do the VMEXIT_LITE mitigation if needed).
Suggested-by: Pawan Gupta <pawan.kumar.gupta@xxxxxxxxxxxxxxx>
Signed-off-by: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
---
arch/x86/kernel/cpu/bugs.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 47a01d4028f6..68bed17f0980 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -1605,20 +1605,20 @@ static void __init spectre_v2_determine_rsb_fill_type_at_vmexit(enum spectre_v2_
case SPECTRE_V2_NONE:
return;
- case SPECTRE_V2_EIBRS_LFENCE:
case SPECTRE_V2_EIBRS:
+ case SPECTRE_V2_EIBRS_LFENCE:
+ case SPECTRE_V2_EIBRS_RETPOLINE:
if (boot_cpu_has_bug(X86_BUG_EIBRS_PBRSB)) {
- setup_force_cpu_cap(X86_FEATURE_RSB_VMEXIT_LITE);
pr_info("Spectre v2 / PBRSB-eIBRS: Retire a single CALL on VMEXIT\n");
+ setup_force_cpu_cap(X86_FEATURE_RSB_VMEXIT_LITE);
}
return;
- case SPECTRE_V2_EIBRS_RETPOLINE:
case SPECTRE_V2_RETPOLINE:
case SPECTRE_V2_LFENCE:
case SPECTRE_V2_IBRS:
- setup_force_cpu_cap(X86_FEATURE_RSB_VMEXIT);
pr_info("Spectre v2 / SpectreRSB : Filling RSB on VMEXIT\n");
+ setup_force_cpu_cap(X86_FEATURE_RSB_VMEXIT);
return;
}
--
2.47.0
