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Message-ID: <20230817090727.GBZN3jT0+gH2iTyeOF@fat_crate.local>
Date: Thu, 17 Aug 2023 11:07:27 +0200
From: Borislav Petkov <bp@...en8.de>
To: Josh Poimboeuf <jpoimboe@...nel.org>
Cc: Nikolay Borisov <nik.borisov@...e.com>, X86 ML <x86@...nel.org>,
Josh Poimboeuf <jpoimboe@...hat.com>,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86/srso: Correct the mitigation status when SMT is
disabled
From: "Borislav Petkov (AMD)" <bp@...en8.de>
Date: Tue, 15 Aug 2023 11:53:13 +0200
Subject: [PATCH] x86/srso: Correct the mitigation status when SMT is disabled
Specify how is SRSO mitigated when SMT is disabled. Also, correct the
SMT check for that.
Fixes: e9fbc47b818b ("x86/srso: Disable the mitigation on unaffected configurations")
Suggested-by: Josh Poimboeuf <jpoimboe@...nel.org>
Signed-off-by: Borislav Petkov (AMD) <bp@...en8.de>
Link: https://lore.kernel.org/r/20230814200813.p5czl47zssuej7nv@treble
---
arch/x86/kernel/cpu/bugs.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c
index 9026e3fe9f6c..f081d26616ac 100644
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -2428,8 +2428,7 @@ static void __init srso_select_mitigation(void)
* Zen1/2 with SMT off aren't vulnerable after the right
* IBPB microcode has been applied.
*/
- if ((boot_cpu_data.x86 < 0x19) &&
- (!cpu_smt_possible() || (cpu_smt_control == CPU_SMT_DISABLED))) {
+ if (boot_cpu_data.x86 < 0x19 && !cpu_smt_possible()) {
setup_force_cpu_cap(X86_FEATURE_SRSO_NO);
return;
}
@@ -2714,7 +2713,7 @@ static ssize_t retbleed_show_state(char *buf)
static ssize_t srso_show_state(char *buf)
{
if (boot_cpu_has(X86_FEATURE_SRSO_NO))
- return sysfs_emit(buf, "Not affected\n");
+ return sysfs_emit(buf, "Mitigation: SMT disabled\n");
return sysfs_emit(buf, "%s%s\n",
srso_strings[srso_mitigation],
--
2.42.0.rc0.25.ga82fb66fed25
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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