Re: [PATCH 0/5] KVM: arm64: Reorganise vcpu first run

[Marc Zyngier <maz@kernel.org>]

On Fri, 15 Oct 2021 11:05:48 +0100,
Andrew Jones <drjones@redhat.com> wrote:
> 
> On Fri, Oct 15, 2021 at 11:49:00AM +0200, Andrew Jones wrote:
> > On Fri, Oct 15, 2021 at 10:08:17AM +0100, Marc Zyngier wrote:
> > > KVM/arm64 relies heavily on a bunch of things to be done on the first
> > > run of the vcpu. We also do a bunch of things on PID change. It turns
> > > out that these two things are pretty similar (the first PID change is
> > > also the first run).
> > > 
> > > This small series aims at simplifying all that, and to get rid of the
> > > vcpu->arch.has_run_once state.
> > > 
> > > Marc Zyngier (5):
> > >   KVM: arm64: Move SVE state mapping at HYP to finalize-time
> > >   KVM: arm64: Move kvm_arch_vcpu_run_pid_change() out of line
> > >   KVM: arm64: Merge kvm_arch_vcpu_run_pid_change() and
> > >     kvm_vcpu_first_run_init()
> > >   KVM: arm64: Restructure the point where has_run_once is advertised
> > 
> > Maybe do the restructuring before the merging in order to avoid the
> > potential for bizarre states?

Yup, can do.

> 
> Also, before we do the merge I think we need to duplicate the
> 
>         if (unlikely(!kvm_vcpu_initialized(vcpu)))
>                 return -ENOEXEC;
> 
> that we currently have above the call of kvm_vcpu_first_run_init()
> into kvm_arch_vcpu_run_pid_change() because
> kvm_arch_vcpu_run_pid_change() is called before kvm_arch_vcpu_ioctl_run()
> in KVM_RUN.

Well spotted.

I think this check should be moved into kvm_arch_vcpu_run_pid_change()
instead of duplicated though, just like we have the check for
'finalized' there. After all, they are the two sides of the same coin.

This nicely moves all checks on the slow path.

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.