Re: [PATCH v3 01/13] x86/fpu/xstate: Avoid getting xstate address of init_fpstate if fpstate contains the component

...

We have this [1]:

  if (fpu_state_size_dynamic())
          mask &= (header.xfeatures | xinit->header.xcomp_bv);

If header.xfeatures[18] = 0 then mask[18] = 0 because xinit->header.xcomp_bv[18] = 0. Then, it won't hit that code. So, I'm confused about the problem that you described here.

Read the suggested changelog I wrote in my reply to Mingwei.

TLDR:

    xsave.header.xfeatures[18] = 1
    xinit.header.xfeatures[18] = 0
->  mask[18] = 1
->  __raw_xsave_addr(xsave, 18)     <- Success
->  __raw_xsave_addr(xinit, 18)     <- WARN

Thanks,

    tglx

Hi Thomas,

Thanks for the review and I will provide the next version separately from the series, since this one is independent from the rest.

Chang: to reproduce this issue, you can simply run the amx_test in the kvm selftest directory.

Thanks. -Mingwei