[PATCH 3/4] arm64: KVM: let other tasks run when hitting WFE

Will Deacon will.deacon at arm.com
Fri Jul 19 10:25:25 EDT 2013

On Fri, Jul 19, 2013 at 02:53:54PM +0100, Marc Zyngier wrote:
> So far, when a guest executes WFE (like when waiting for a spinlock
> to become unlocked), we don't do a thing and let it run uninterrupted.
> Another option is to trap a blocking WFE and offer the opportunity
> to the scheduler to switch to another task, potentially giving the
> vcpu holding the spinlock a chance to run sooner.
> Signed-off-by: Marc Zyngier <marc.zyngier at arm.com>


> +static int kvm_handle_wfx(struct kvm_vcpu *vcpu, struct kvm_run *run)
>  {
> -	kvm_vcpu_block(vcpu);
> +	if (kvm_vcpu_get_hsr(vcpu) & 1)
> +		cond_resched();

The hardcoded `1' doesn't make it obvious that we're treating wfi and wfe
differently. Could you use a #define for that bit in hsr.iss please?


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