Messages in this thread Patch in this message | | | Date | Tue, 09 Apr 2024 17:11:32 -0000 | From | "tip-bot2 for Borislav Petkov (AMD)" <> | Subject | [tip: x86/alternatives] x86/alternatives: Catch late X86_FEATURE modifiers |
| |
The following commit has been merged into the x86/alternatives branch of tip:
Commit-ID: ee8962082a4413dba1a1b3d3d23490c5221f3b8a Gitweb: https://git.kernel.org/tip/ee8962082a4413dba1a1b3d3d23490c5221f3b8a Author: Borislav Petkov (AMD) <bp@alien8.de> AuthorDate: Wed, 27 Mar 2024 16:43:14 +01:00 Committer: Borislav Petkov (AMD) <bp@alien8.de> CommitterDate: Tue, 09 Apr 2024 18:03:53 +02:00
x86/alternatives: Catch late X86_FEATURE modifiers
After alternatives have been patched, changes to the X86_FEATURE flags won't take effect and could potentially even be wrong.
Warn about it.
This is something which has been long overdue.
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Tested-by: Srikanth Aithal <sraithal@amd.com> Link: https://lore.kernel.org/r/20240327154317.29909-3-bp@alien8.de --- arch/x86/include/asm/cpufeature.h | 8 ++++++-- arch/x86/kernel/cpu/cpuid-deps.c | 3 +++ 2 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/arch/x86/include/asm/cpufeature.h b/arch/x86/include/asm/cpufeature.h index 686e92d..f07687d 100644 --- a/arch/x86/include/asm/cpufeature.h +++ b/arch/x86/include/asm/cpufeature.h @@ -150,8 +150,12 @@ extern const char * const x86_bug_flags[NBUGINTS*32]; extern void setup_clear_cpu_cap(unsigned int bit); extern void clear_cpu_cap(struct cpuinfo_x86 *c, unsigned int bit); -#define setup_force_cpu_cap(bit) do { \ - set_cpu_cap(&boot_cpu_data, bit); \ +#define setup_force_cpu_cap(bit) do { \ + \ + if (!boot_cpu_has(bit)) \ + WARN_ON(alternatives_patched); \ + \ + set_cpu_cap(&boot_cpu_data, bit); \ set_bit(bit, (unsigned long *)cpu_caps_set); \ } while (0) diff --git a/arch/x86/kernel/cpu/cpuid-deps.c b/arch/x86/kernel/cpu/cpuid-deps.c index b717420..5dd427c 100644 --- a/arch/x86/kernel/cpu/cpuid-deps.c +++ b/arch/x86/kernel/cpu/cpuid-deps.c @@ -114,6 +114,9 @@ static void do_clear_cpu_cap(struct cpuinfo_x86 *c, unsigned int feature) if (WARN_ON(feature >= MAX_FEATURE_BITS)) return; + if (boot_cpu_has(feature)) + WARN_ON(alternatives_patched); + clear_feature(c, feature); /* Collect all features to disable, handling dependencies */
| |