4.14-stable review patch. If anyone has any objections, please let me know.
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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: */