This is a note to let you know that I've just added the patch titled

x86/fpu: Make XSAVE check the base CPUID features before enabling

to the 4.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: x86-fpu-make-xsave-check-the-base-cpuid-features-before-enabling.patch and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From ccb18db2ab9d923df07e7495123fe5fb02329713 Mon Sep 17 00:00:00 2001

From: Andi Kleen ak@linux.intel.com Date: Fri, 13 Oct 2017 14:56:44 -0700 Subject: x86/fpu: Make XSAVE check the base CPUID features before enabling

From: Andi Kleen ak@linux.intel.com

commit ccb18db2ab9d923df07e7495123fe5fb02329713 upstream.

Before enabling XSAVE, not only check the XSAVE specific CPUID bits, but also the base CPUID features of the respective XSAVE feature. This allows to disable individual XSAVE states using the existing clearcpuid= option, which can be useful for performance testing and debugging, and also in general avoids inconsistencies.

Signed-off-by: Andi Kleen ak@linux.intel.com Reviewed-by: Thomas Gleixner tglx@linutronix.de Cc: Linus Torvalds torvalds@linux-foundation.org Cc: Peter Zijlstra peterz@infradead.org Link: http://lkml.kernel.org/r/20171013215645.23166-5-andi@firstfloor.org Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- arch/x86/kernel/fpu/xstate.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+)

--- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -15,6 +15,7 @@ #include <asm/fpu/xstate.h>

#include <asm/tlbflush.h> +#include <asm/cpufeature.h>

/* * Although we spell it out in here, the Processor Trace @@ -36,6 +37,19 @@ static const char *xfeature_names[] = "unknown xstate feature" , };

+static short xsave_cpuid_features[] __initdata = { + X86_FEATURE_FPU, + X86_FEATURE_XMM, + X86_FEATURE_AVX, + X86_FEATURE_MPX, + X86_FEATURE_MPX, + X86_FEATURE_AVX512F, + X86_FEATURE_AVX512F, + X86_FEATURE_AVX512F, + X86_FEATURE_INTEL_PT, + X86_FEATURE_PKU, +}; + /* * Mask of xstate features supported by the CPU and the kernel: */ @@ -726,6 +740,7 @@ void __init fpu__init_system_xstate(void unsigned int eax, ebx, ecx, edx; static int on_boot_cpu __initdata = 1; int err; + int i;

WARN_ON_FPU(!on_boot_cpu); on_boot_cpu = 0; @@ -759,6 +774,14 @@ void __init fpu__init_system_xstate(void goto out_disable; }

+ /* + * Clear XSAVE features that are disabled in the normal CPUID. + */ + for (i = 0; i < ARRAY_SIZE(xsave_cpuid_features); i++) { + if (!boot_cpu_has(xsave_cpuid_features[i])) + xfeatures_mask &= ~BIT(i); + } + xfeatures_mask &= fpu__get_supported_xfeatures_mask();

/* Enable xstate instructions to be able to continue with initialization: */

Patches currently in stable-queue which might be from ak@linux.intel.com are

queue-4.14/bitops-add-clear-set_bit32-to-linux-bitops.h.patch queue-4.14/x86-fpu-remove-the-explicit-clearing-of-xsave-dependent-features.patch queue-4.14/x86-cpuid-add-generic-table-for-cpuid-dependencies.patch queue-4.14/x86-cpuid-prevent-out-of-bound-access-in-do_clear_cpu_cap.patch queue-4.14/x86-fpu-parse-clearcpuid-as-early-xsave-argument.patch queue-4.14/x86-fpu-make-xsave-check-the-base-cpuid-features-before-enabling.patch