Messages in this thread | | | Date | Thu, 9 Feb 2017 16:45:41 -0800 | From | Yu-cheng Yu <> | Subject | Re: [PATCH v2] x86/fpu: copy MXCSR & MXCSR_FLAGS with SSE/YMM state |
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On Thu, Feb 09, 2017 at 06:43:47PM -0500, Rik van Riel wrote: > /* > + * Weird legacy quirk: SSE and YMM states store information in the > + * MXCSR and MXCSR_FLAGS fields of the FP area. That means if the FP > + * area is marked as unused in the xfeatures header, we need to copy > + * MXCSR and MXCSR_FLAGS if either SSE or YMM are in use. > + */ > +static inline bool xfeatures_need_mxcsr_copy(u64 xfeatures) > +{ > + if (!(xfeatures & (XFEATURE_MASK_SSE|XFEATURE_MASK_YMM))) > + return 0; > + > + if (xfeatures & XFEATURE_MASK_FP) > + return 0; > + > + return 1; > +}
Would you consider separating MXCSR & MXCSR_FLAGS from XFEATURE_MASK_FP. Here we assume if both xstate[0] and xstate[1] are being copied, then there is no need to copy MXCSR/MXCSR_FLAGS again. What if only xstate[0] is copied and MXCSR/MXCSR_FLAGS is invalid?
Yu-cheng
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