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authorBorislav Petkov <bp@suse.de>2020-06-15 08:51:25 +0200
committerBorislav Petkov <bp@suse.de>2020-06-16 23:14:47 +0200
commita5ce9f2bb665d1d2b31f139a02dbaa2dfbb62fa6 (patch)
tree11fa6b8e87974918205ab28df45ccfa72aa305dc
parentb3a9e3b9622ae10064826dccb4f7a52bd88c7407 (diff)
downloadlwn-a5ce9f2bb665d1d2b31f139a02dbaa2dfbb62fa6.tar.gz
lwn-a5ce9f2bb665d1d2b31f139a02dbaa2dfbb62fa6.zip
x86/speculation: Merge one test in spectre_v2_user_select_mitigation()
Merge the test whether the CPU supports STIBP into the test which determines whether STIBP is required. Thus try to simplify what is already an insane logic. Remove a superfluous newline in a comment, while at it. Signed-off-by: Borislav Petkov <bp@suse.de> Cc: Anthony Steinhauser <asteinhauser@google.com> Link: https://lkml.kernel.org/r/20200615065806.GB14668@zn.tnic
-rw-r--r--arch/x86/kernel/cpu/bugs.c13
1 files changed, 4 insertions, 9 deletions
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 0b71970d2d3d..7beaefa9d198 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -763,10 +763,12 @@ spectre_v2_user_select_mitigation(enum spectre_v2_mitigation_cmd v2_cmd)
}
/*
- * If enhanced IBRS is enabled or SMT impossible, STIBP is not
+ * If no STIBP, enhanced IBRS is enabled or SMT impossible, STIBP is not
* required.
*/
- if (!smt_possible || spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED)
+ if (!boot_cpu_has(X86_FEATURE_STIBP) ||
+ !smt_possible ||
+ spectre_v2_enabled == SPECTRE_V2_IBRS_ENHANCED)
return;
/*
@@ -778,12 +780,6 @@ spectre_v2_user_select_mitigation(enum spectre_v2_mitigation_cmd v2_cmd)
boot_cpu_has(X86_FEATURE_AMD_STIBP_ALWAYS_ON))
mode = SPECTRE_V2_USER_STRICT_PREFERRED;
- /*
- * If STIBP is not available, clear the STIBP mode.
- */
- if (!boot_cpu_has(X86_FEATURE_STIBP))
- mode = SPECTRE_V2_USER_NONE;
-
spectre_v2_user_stibp = mode;
set_mode:
@@ -1270,7 +1266,6 @@ static int ib_prctl_set(struct task_struct *task, unsigned long ctrl)
* Indirect branch speculation is always disabled in strict
* mode. It can neither be enabled if it was force-disabled
* by a previous prctl call.
-
*/
if (spectre_v2_user_ibpb == SPECTRE_V2_USER_STRICT ||
spectre_v2_user_stibp == SPECTRE_V2_USER_STRICT ||