Re: [PATCH v6 02/25] x86/fpu/xstate: Fix guest fpstate allocation size calculation

[Edgecombe, Rick P]

On Fri, 2023-09-15 at 10:45 +0800, Yang, Weijiang wrote:
> On 9/15/2023 6:45 AM, Edgecombe, Rick P wrote:
> > On Thu, 2023-09-14 at 02:33 -0400, Yang Weijiang wrote:
> > > Fix guest xsave area allocation size from
> > > fpu_user_cfg.default_size
> > > to
> > > fpu_kernel_cfg.default_size so that the xsave area size is
> > > consistent
> > > with fpstate->size set in __fpstate_reset().
> > > 
> > > With the fix, guest fpstate size is sufficient for KVM supported
> > > guest
> > > xfeatures.
> > > 
> > > Signed-off-by: Yang Weijiang <weijiang.yang@xxxxxxxxx>
> > There is no fix (Fixes: ...) here, right?
> 
> Ooh, I got it lost during rebase, thanks!
> 
> > I think this change is needed
> > to make sure KVM guests can support supervisor features. But KVM
> > CET
> > support (to follow in future patches) will be the first one, right?
> 
> Exactly, the existing code takes only user xfeatures into account,
> and we have more
> and more CPU features rely on supervisor xstates.

If KVM is not using any supervisor features, then pre CET KVM support I
think the current code is more correct.