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Date: Sat, 17 Feb 2018 02:13:02 -0800 From: tip-bot for Borislav Petkov <tipbot@...or.com> To: linux-tip-commits@...r.kernel.org Cc: arjan@...ux.intel.com, dan.j.williams@...el.com, mingo@...nel.org, luto@...nel.org, bp@...en8.de, gregkh@...uxfoundation.org, hpa@...or.com, dwmw2@...radead.org, linux-kernel@...r.kernel.org, torvalds@...ux-foundation.org, ashok.raj@...el.com, dave.hansen@...ux.intel.com, bp@...e.de, peterz@...radead.org, jpoimboe@...hat.com, tglx@...utronix.de Subject: [tip:x86/pti] x86/CPU: Check CPU feature bits after microcode upgrade Commit-ID: 42ca8082e260dcfd8afa2afa6ec1940b9d41724c Gitweb: https://git.kernel.org/tip/42ca8082e260dcfd8afa2afa6ec1940b9d41724c Author: Borislav Petkov <bp@...e.de> AuthorDate: Fri, 16 Feb 2018 12:26:40 +0100 Committer: Ingo Molnar <mingo@...nel.org> CommitDate: Sat, 17 Feb 2018 08:43:55 +0100 x86/CPU: Check CPU feature bits after microcode upgrade 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@...el.com> Tested-by: Ashok Raj <ashok.raj@...el.com> Signed-off-by: Borislav Petkov <bp@...e.de> Reviewed-by: Ashok Raj <ashok.raj@...el.com> Cc: Andy Lutomirski <luto@...nel.org> Cc: Arjan van de Ven <arjan@...ux.intel.com> Cc: Borislav Petkov <bp@...en8.de> Cc: Dan Williams <dan.j.williams@...el.com> Cc: Dave Hansen <dave.hansen@...ux.intel.com> Cc: David Woodhouse <dwmw2@...radead.org> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org> Cc: Josh Poimboeuf <jpoimboe@...hat.com> Cc: Linus Torvalds <torvalds@...ux-foundation.org> Cc: Peter Zijlstra <peterz@...radead.org> Cc: Thomas Gleixner <tglx@...utronix.de> Link: http://lkml.kernel.org/r/20180216112640.11554-4-bp@alien8.de Signed-off-by: Ingo Molnar <mingo@...nel.org> --- 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 84f1cd8..348cf48 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"); }
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