Kernel/linux-stable
1
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git synced 2025-01-06 05:06:29 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

x86/CPU: Check CPU feature bits after microcode upgrade

Browse Source 
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>
Tested-by: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Ashok Raj <ashok.raj@intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20180216112640.11554-4-bp@alien8.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Borislav Petkov 2018-02-16 12:26:40 +01:00 committed by Ingo Molnar
parent 1008c52c09
commit 42ca8082e2
1 changed files with 20 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
arch/x86/kernel/cpu/common.c
View File

@ -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");
}