Re: [PATCH v3 05/10] KVM: TDX: restore host xsave state when exit from the guest TD

[Paolo Bonzini]

On Mon, Mar 10, 2025 at 8:24 AM Xiaoyao Li <xiaoyao.li@xxxxxxxxx> wrote:
>
> On 3/8/2025 5:20 AM, Paolo Bonzini wrote:
> > From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
> >
> > On exiting from the guest TD, xsave state is clobbered; restore it.
>
> I prefer the implementation as this patch, which is straightforward.
> (I would be much better if the changelog can describe more)

Ok:

Do not use kvm_load_host_xsave_state(), as it relies on vcpu->arch
to find out whether other KVM_RUN code has loaded guest state into
XCR0/PKRU/XSS or not.  In the case of TDX, the exit values are known
independent of the guest CR0 and CR4, and in fact the latter are not
available.

Thanks!

Paolo