The following commit has been merged into the x86/urgent branch of tip:
Commit-ID: f337a6a21e2fd67eadea471e93d05dd37baaa9be Gitweb: https://git.kernel.org/tip/f337a6a21e2fd67eadea471e93d05dd37baaa9be Author: Sean Christopherson seanjc@google.com AuthorDate: Tue, 09 Apr 2024 10:51:05 -07:00 Committer: Ingo Molnar mingo@kernel.org CommitterDate: Wed, 10 Apr 2024 16:22:47 +02:00
x86/cpu: Actually turn off mitigations by default for SPECULATION_MITIGATIONS=n
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 8f6affd..07ad53b 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) {