[PATCH] KVM: arm64: Move management of __hyp_running_vcpu to load/put on VHE

[Oliver Upton]

On Thu, May 02, 2024 at 04:40:30PM +0100, Marc Zyngier wrote:
> The per-CPU host context structure contains a __hyp_running_vcpu that
> serves as a replacement for kvm_get_current_vcpu() in contexts where
> we cannot make direct use of it (such as in the nVHE hypervisor).
> Since there is a lot of common code between nVHE and VHE, the latter
> also populates this field even if kvm_get_running_vcpu() always works.
> 
> We currently pretty inconsistent when populating __hyp_running_vcpu
> to point to the currently running vcpu:
> 
> - on {n,h}VHE, we set __hyp_running_vcpu on entry to __kvm_vcpu_run
>   and clear it on exit.
> 
> - on VHE, we set __hyp_running_vcpu on entry to __kvm_vcpu_run_vhe
>   and never clear it, effectively leaving a dangling pointer...
> 
> VHE is obviously the odd one here. Although we could make it behave
> just like nVHE, this wouldn't match the behaviour of KVM with VHE,
> where the load phase is where most of the context-switch gets done.
> 
> So move all the __hyp_running_vcpu management to the VHE-specific
> load/put phases, giving us a bit more sanity and matching the
> behaviour of kvm_get_running_vcpu().
> 
> Signed-off-by: Marc Zyngier <maz at kernel.org>

Reviewed-by: Oliver Upton <oliver.upton at linux.dev>

-- 
Thanks,
Oliver