Messages in this thread | | | Subject | Re: [PATCH 1/6] x86/fpu/xstate: Fix small issues before adding supervisor xstates | From | Yu-cheng Yu <> | Date | Fri, 22 Nov 2019 13:22:37 -0800 |
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On Wed, 2019-10-09 at 08:58 -0700, Borislav Petkov wrote: > On Wed, Sep 25, 2019 at 08:10:17AM -0700, Yu-cheng Yu wrote: > > In response to earlier comments, fix small issues before introducing XSAVES > > supervisor states: > > - Add spaces around '*'. > > - Fix comments of xfeature_is_supervisor(). > > - Replace ((u64)1 << 63) with XCOMP_BV_COMPACTED_FORMAT. > > > > No functional changes from this patch. > > > > Signed-off-by: Yu-cheng Yu <yu-cheng.yu@intel.com> > > Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com> > > Reviewed-by: Tony Luck <tony.luck@intel.com> > > --- > > arch/x86/kernel/fpu/xstate.c | 15 ++++++--------- > > 1 file changed, 6 insertions(+), 9 deletions(-) > > > > diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c > > index e5cb67d67c03..b793fc2156b9 100644 > > --- a/arch/x86/kernel/fpu/xstate.c > > +++ b/arch/x86/kernel/fpu/xstate.c > > @@ -60,7 +60,7 @@ u64 xfeatures_mask __read_mostly; > > > > static unsigned int xstate_offsets[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1}; > > static unsigned int xstate_sizes[XFEATURE_MAX] = { [ 0 ... XFEATURE_MAX - 1] = -1}; > > -static unsigned int xstate_comp_offsets[sizeof(xfeatures_mask)*8]; > > +static unsigned int xstate_comp_offsets[sizeof(xfeatures_mask) * 8]; > > > > /* > > * The XSAVE area of kernel can be in standard or compacted format; > > @@ -110,12 +110,8 @@ EXPORT_SYMBOL_GPL(cpu_has_xfeatures); > > static int xfeature_is_supervisor(int xfeature_nr) > > { > > /* > > - * We currently do not support supervisor states, but if > > - * we did, we could find out like this. > > - * > > - * SDM says: If state component 'i' is a user state component, > > - * ECX[0] return 0; if state component i is a supervisor > > - * state component, ECX[0] returns 1. > > + * Extended State Enumeration Sub-leaves (EAX = 0DH, ECX = n, n > 1) > > + * returns ECX[0] set to (1) for a supervisor state. > > "... and cleared (0) for a user state." > > I believe it is is clearer this way. > > > */ > > u32 eax, ebx, ecx, edx; > > > > Since you're touching this function: make it return bool as it is used > in boolean context only and have it return simply: > > return ecx & 1;
This implicitly converts a u32 to a bool. By looking at it, I think it should be OK, but wonder if anything overlooked? I would be happy to make this a separate patch.
Yu-cheng
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