On 1/18/22 11:04 PM, Like Xu wrote:
> Remove the XFEATURE_MASK_SSE bit as part of the XFEATURE_MASK_EXTEND
> and opportunistically, move it into the context of its unique user KVM.
Is this a problem for xstate_required_size()? The rules for the CPUID
sub-functions <=1 are different than those for >1. Most importantly,
'eax' doesn't enumerate the size of the feature for the XFEATURE_SSE
sub-leaf.
I think XFEATURE_MASK_EXTEND was being used to avoid that oddity:
> u32 xstate_required_size(u64 xstate_bv, bool compacted)
> {
> int feature_bit = 0;
> u32 ret = XSAVE_HDR_SIZE + XSAVE_HDR_OFFSET;
>
> xstate_bv &= XFEATURE_MASK_EXTEND;
> while (xstate_bv) {
> if (xstate_bv & 0x1) {
> u32 eax, ebx, ecx, edx, offset;
> cpuid_count(0xD, feature_bit, &eax, &ebx, &ecx, &edx);
> /* ECX[1]: 64B alignment in compacted form */
> if (compacted)
> offset = (ecx & 0x2) ? ALIGN(ret, 64) : ret;
> else
> offset = ebx;
> ret = max(ret, offset + eax);
> }
>
> xstate_bv >>= 1;
> feature_bit++;
> }
>
> return ret;
> }
