Re: [RFC PATCH 26/35] KVM: SVM: Guest FPU state save/restore not needed for SEV-ES guest

From: Sean Christopherson
Date: Tue Sep 15 2020 - 13:25:37 EST


On Tue, Sep 15, 2020 at 09:25:18AM -0500, Tom Lendacky wrote:
> On 9/14/20 4:39 PM, Sean Christopherson wrote:
> > On Mon, Sep 14, 2020 at 03:15:40PM -0500, Tom Lendacky wrote:
> >> From: Tom Lendacky <thomas.lendacky@xxxxxxx>
> >>
> >> The guest FPU is automatically restored on VMRUN and saved on VMEXIT by
> >> the hardware, so there is no reason to do this in KVM.
> >
> > I assume hardware has its own buffer? If so, a better approach would be to
> > not allocate arch.guest_fpu in the first place, and then rework KVM to key
> > off !guest_fpu.
>
> Yup, let me look into that.

Heh, it's on our todo list as well :-)