On Tue, Nov 9, 2021 at 8:43 AM Brian Geffon <bgeffon@xxxxxxxxxx> wrote: > What's interesting is that writing to init_pkru fails with -EINVAL for me, > and I've traced it down to get_xsave_addr() returning NULL on the following > check: > > /* > * This assumes the last 'xsave*' instruction to > * have requested that 'xfeature_nr' be saved. > * If it did not, we might be seeing and old value > * of the field in the buffer. > * > * This can happen because the last 'xsave' did not > * request that this feature be saved (unlikely) > * or because the "init optimization" caused it > * to not be saved. > */ > if (!(xsave->header.xfeatures & BIT_ULL(xfeature_nr))) > return NULL; > Sorry, I should have probably also shared the value of xfeatures at this point is 0x3: which appears to be: (X86_FEATURE_FPU | X86_FEATURE_XMM) Brian
