Re: [Xen-devel] [V3] x86/xsaves: fix overwriting between non-lazy/lazy xsaves

[Shuai Ruan <shuai.ruan@xxxxxxxxxxxxxxx>]

On Wed, Mar 09, 2016 at 03:25:58AM -0700, Jan Beulich wrote:
> Btw., one more thing: Can't the exclusion of FP and SSE states in the logic
> determining which state set to save be extended to also include YMM? If saved,
> YMM will also always live at a fixed place (an ASSERT() or BUG_ON() to verify
> would of course be desirable). And if the guest didn't touch YMM registers, 
> the
> respective bit in the mask won't be set anyway.
> 
YMM do live at the begining of the xsave extended area. But when we
exclude YMM like FP/SSE states ,if guest set YMM | XSTATE_NONLAZY respective 
bitin xcro_accum, the over-writing may happend too. In such case , 
vcpu_xsave_mask
will return XSTATE_NONLAZY, the first xstate of XSTATE_NONLAZY will be
xsaved at the begining of xsave extended area which may over-write YMM
state.
Do I miss something ?
> Jan
> 
> 
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