Messages in this thread Patch in this message | | | From | Borislav Petkov <> | Subject | [PATCH 3/3] x86/CPU: Check CPU feature bits after microcode upgrade | Date | Fri, 16 Feb 2018 12:26:40 +0100 |
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From: Borislav Petkov <bp@suse.de>
With some microcode upgrades, new CPUID features can become visible on the CPU. Check what the kernel has mirrored now and issue a warning hinting at possible things the user/admin can do to make use of the newly visible features.
Originally-by: Ashok Raj <ashok.raj@intel.com> Signed-off-by: Borislav Petkov <bp@suse.de> --- arch/x86/kernel/cpu/common.c | 20 ++++++++++++++++++++ 1 file changed, 20 insertions(+)
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c index 82c142b33bf3..768eb680db8d 100644 --- a/arch/x86/kernel/cpu/common.c +++ b/arch/x86/kernel/cpu/common.c @@ -1757,5 +1757,25 @@ core_initcall(init_cpu_syscore); */ void microcode_check(void) { + struct cpuinfo_x86 info; + perf_check_microcode(); + + /* Reload CPUID max function as it might've changed. */ + info.cpuid_level = cpuid_eax(0); + + /* + * Copy all capability leafs to pick up the synthetic ones so that + * memcmp() below doesn't fail on that. The ones coming from CPUID will + * get overwritten in get_cpu_cap(). + */ + memcpy(&info.x86_capability, &boot_cpu_data.x86_capability, sizeof(info.x86_capability)); + + get_cpu_cap(&info); + + if (!memcmp(&info.x86_capability, &boot_cpu_data.x86_capability, sizeof(info.x86_capability))) + return; + + pr_warn("x86/CPU: CPU features have changed after loading microcode, but might not take effect.\n"); + pr_warn("x86/CPU: Please consider either early loading through initrd/built-in or a potential BIOS update.\n"); } -- 2.13.0
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