From b5aab4b87f82f5f3d78053df16faa72c62457c7c Mon Sep 17 00:00:00 2001
From: Borislav Petkov <bp@suse.de>
Date: Wed, 20 Apr 2022 11:53:21 +0000
Subject: [PATCH] x86/speculation: Merge one test in
spectre_v2_user_select_mitigation()
stable inclusion
from stable-v4.19.234
commit d86fc674172edc0794f84198405f59f00b71512a
category: bugfix
bugzilla: 186453, https://gitee.com/src-openeuler/kernel/issues/I50WBM
CVE: CVE-2022-0001
--------------------------------
commit a5ce9f2bb665d1d2b31f139a02dbaa2dfbb62fa6 upstream.
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
[fllinden@amazon.com: fixed contextual conflict (comment) for 4.19]
Signed-off-by: Frank van der Linden <fllinden@amazon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Conflicts:
arch/x85/kernel/cpu/bugs.c
Signed-off-by: Chen Jiahao <chenjiahao16@huawei.com>
Reviewed-by: Hanjun Guo <guohanjun@huawei.com>
Reviewed-by: Liao Chang <liaochang1@huawei.com>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>
---
arch/x86/kernel/cpu/bugs.c | 12 ++++--------
1 file changed, 4 insertions(+), 8 deletions(-)
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 54ec900bd259..7dd614930801 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -756,10 +756,12 @@ 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;
/*
@@ -771,12 +773,6 @@ 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:
--
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