6.16-stable review patch. If anyone has any objections, please let me know.
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From: Pawan Gupta pawan.kumar.gupta@linux.intel.com
[ Upstream commit 8374a2719df2a00781e6821e373d7de71390d1b4 ]
In preparation to allow ITS to also enable stuffing aka Call Depth Tracking (CDT) independently of retbleed, introduce a helper cdt_possible().
Signed-off-by: Pawan Gupta pawan.kumar.gupta@linux.intel.com Signed-off-by: Borislav Petkov (AMD) bp@alien8.de Link: https://lore.kernel.org/20250611-eibrs-fix-v4-5-5ff86cac6c61@linux.intel.com Stable-dep-of: ab9f2388e0b9 ("x86/bugs: Allow ITS stuffing in eIBRS+retpoline mode also") Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/kernel/cpu/bugs.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-)
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 937971fde749..0426500307f0 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -1124,6 +1124,19 @@ early_param("nospectre_v1", nospectre_v1_cmdline);
enum spectre_v2_mitigation spectre_v2_enabled __ro_after_init = SPECTRE_V2_NONE;
+/* Depends on spectre_v2 mitigation selected already */ +static inline bool cdt_possible(enum spectre_v2_mitigation mode) +{ + if (!IS_ENABLED(CONFIG_MITIGATION_CALL_DEPTH_TRACKING) || + !IS_ENABLED(CONFIG_MITIGATION_RETPOLINE)) + return false; + + if (mode == SPECTRE_V2_RETPOLINE) + return true; + + return false; +} + #undef pr_fmt #define pr_fmt(fmt) "RETBleed: " fmt
@@ -1272,7 +1285,7 @@ static void __init retbleed_update_mitigation(void) retbleed_mitigation = RETBLEED_MITIGATION_STUFF;
if (retbleed_mitigation == RETBLEED_MITIGATION_STUFF && - spectre_v2_enabled != SPECTRE_V2_RETPOLINE) { + !cdt_possible(spectre_v2_enabled)) { pr_err("WARNING: retbleed=stuff depends on spectre_v2=retpoline\n"); retbleed_mitigation = RETBLEED_MITIGATION_NONE; }