Messages in this thread | | | Date | Thu, 12 Oct 2017 10:11:26 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH v9 4/5] x86/xsave: Make XSAVE check the base CPUID features before enabling |
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* Andi Kleen <andi@firstfloor.org> wrote:
> From: Andi Kleen <ak@linux.intel.com> > > 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. > > v2: > Add curly brackets (Thomas Gleixner) > Signed-off-by: Andi Kleen <ak@linux.intel.com> > --- > arch/x86/kernel/fpu/xstate.c | 23 +++++++++++++++++++++++ > 1 file changed, 23 insertions(+) > > diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c > index f1d5476c9022..924bd895b5ee 100644 > --- 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[] = { > + 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: */
This patch has similar problems to the ones I reported against 2/5.
Thanks,
Ingo
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