Messages in this thread | | | Date | Thu, 13 Oct 2022 10:21:28 -0700 | Subject | Re: [PATCH] x86/fpu: Remove dynamic features from xcomp_bv for init_fpstate | From | Dave Hansen <> |
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On 10/13/22 09:23, Chang S. Bae wrote: > > --- a/arch/x86/kernel/fpu/xstate.c > +++ b/arch/x86/kernel/fpu/xstate.c > @@ -1127,8 +1127,12 @@ void __copy_xstate_to_uabi_buf(struct membuf to, > struct fpstate *fpstate, > * non-compacted format disabled features still occupy state space, > * but there is no state to copy from in the compacted > * init_fpstate. The gap tracking will zero these states. > + * > + * In the case of guest fpstate, this user_xfeatures does not > + * dynamically reflect the capacity of the XSAVE buffer but > + * xfeatures does. So AND them together. > */ > - mask = fpstate->user_xfeatures; > + mask = fpstate->user_xfeatures & fpstate->xfeatures;
I'm not sure this is quite right either.
Doesn't kvm expect that all of the ->user_xfeatures will end up being copied out? We surely can't copy them from 'fpstate' if the feature isn't there, but we can't skip them entirely, can we?
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