From f337a6a21e2fd67eadea471e93d05dd37baaa9be Mon Sep 17 00:00:00 2001
From: Sean Christopherson <seanjc@google.com>
Date: Tue, 9 Apr 2024 10:51:05 -0700
Subject: [PATCH] x86/cpu: Actually turn off mitigations by default for
SPECULATION_MITIGATIONS=n
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Initialize cpu_mitigations to CPU_MITIGATIONS_OFF if the kernel is built
with CONFIG_SPECULATION_MITIGATIONS=n, as the help text quite clearly
states that disabling SPECULATION_MITIGATIONS is supposed to turn off all
mitigations by default.
│ If you say N, all mitigations will be disabled. You really
│ should know what you are doing to say so.
As is, the kernel still defaults to CPU_MITIGATIONS_AUTO, which results in
some mitigations being enabled in spite of SPECULATION_MITIGATIONS=n.
Fixes: f43b9876e857 ("x86/retbleed: Add fine grained Kconfig knobs")
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Daniel Sneddon <daniel.sneddon@linux.intel.com>
Cc: stable@vger.kernel.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20240409175108.1512861-2-seanjc@google.com
---
kernel/cpu.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 8f6affd051f77..07ad53b7f1195 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -3207,7 +3207,8 @@ enum cpu_mitigations {
};
static enum cpu_mitigations cpu_mitigations __ro_after_init =
- CPU_MITIGATIONS_AUTO;
+ IS_ENABLED(CONFIG_SPECULATION_MITIGATIONS) ? CPU_MITIGATIONS_AUTO :
+ CPU_MITIGATIONS_OFF;
static int __init mitigations_parse_cmdline(char *arg)
{
--
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