From: Dave Hansen Date: Fri, 7 Oct 2016 16:23:42 +0000 (-0700) Subject: x86/pkeys: Make protection keys an "eager" feature X-Git-Tag: v4.9-rc1~62^2 X-Git-Url: http://git.cascardo.info/?p=cascardo%2Flinux.git;a=commitdiff_plain;h=d4b05923f579c234137317cdf9a5eb69ddab76d1;hp=df610d678893c85b82d3a68eea0d87dd4e03e615 x86/pkeys: Make protection keys an "eager" feature Our XSAVE features are divided into two categories: those that generate FPU exceptions, and those that do not. MPX and pkeys do not generate FPU exceptions and thus can not be used lazily. We disable them when lazy mode is forced on. We have a pair of masks to collect these two sets of features, but XFEATURE_MASK_PKRU was added to the wrong mask: XFEATURE_MASK_LAZY. Fix it by moving the feature to XFEATURE_MASK_EAGER. Note: this only causes problem if you boot with lazy FPU mode (eagerfpu=off) which is *not* the default. It also only affects hardware which is not currently publicly available. It looks like eager mode is going away, but we still need this patch applied to any kernel that has protection keys and lazy mode, which is 4.6 through 4.8 at this point, and 4.9 if the lazy removal isn't sent to Linus for 4.9. Fixes: c8df40098451 ("x86/fpu, x86/mm/pkeys: Add PKRU xsave fields and data structures") Signed-off-by: Dave Hansen Cc: Dave Hansen Cc: stable@vger.kernel.org Link: http://lkml.kernel.org/r/20161007162342.28A49813@viggo.jf.intel.com Signed-off-by: Thomas Gleixner --- diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h index d4957ac72b48..430bacf73074 100644 --- a/arch/x86/include/asm/fpu/xstate.h +++ b/arch/x86/include/asm/fpu/xstate.h @@ -27,11 +27,12 @@ XFEATURE_MASK_YMM | \ XFEATURE_MASK_OPMASK | \ XFEATURE_MASK_ZMM_Hi256 | \ - XFEATURE_MASK_Hi16_ZMM | \ - XFEATURE_MASK_PKRU) + XFEATURE_MASK_Hi16_ZMM) /* Supported features which require eager state saving */ -#define XFEATURE_MASK_EAGER (XFEATURE_MASK_BNDREGS | XFEATURE_MASK_BNDCSR) +#define XFEATURE_MASK_EAGER (XFEATURE_MASK_BNDREGS | \ + XFEATURE_MASK_BNDCSR | \ + XFEATURE_MASK_PKRU) /* All currently supported features */ #define XCNTXT_MASK (XFEATURE_MASK_LAZY | XFEATURE_MASK_EAGER)