Re: [PATCH v7 3/4] KVM: arm64: Dirty quota-based throttling of vcpus

[Marc Zyngier <maz@kernel.org>]

On Sun, 13 Nov 2022 17:05:10 +0000,
Shivam Kumar <shivam.kumar1@nutanix.com> wrote:
> 
> Exit to userspace whenever the dirty quota is exhausted (i.e. dirty count
> equals/exceeds dirty quota) to request more dirty quota.
> 
> Suggested-by: Shaju Abraham <shaju.abraham@nutanix.com>
> Suggested-by: Manish Mishra <manish.mishra@nutanix.com>
> Co-developed-by: Anurag Madnawat <anurag.madnawat@nutanix.com>
> Signed-off-by: Anurag Madnawat <anurag.madnawat@nutanix.com>
> Signed-off-by: Shivam Kumar <shivam.kumar1@nutanix.com>
> ---
>  arch/arm64/kvm/arm.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index 94d33e296e10..850024982dd9 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -746,6 +746,15 @@ static int check_vcpu_requests(struct kvm_vcpu *vcpu)
>  
>  		if (kvm_check_request(KVM_REQ_SUSPEND, vcpu))
>  			return kvm_vcpu_suspend(vcpu);
> +
> +		if (kvm_check_request(KVM_REQ_DIRTY_QUOTA_EXIT, vcpu)) {
> +			struct kvm_run *run = vcpu->run;
> +
> +			run->exit_reason = KVM_EXIT_DIRTY_QUOTA_EXHAUSTED;
> +			run->dirty_quota_exit.count = vcpu->stat.generic.pages_dirtied;
> +			run->dirty_quota_exit.quota = vcpu->dirty_quota;
> +			return 0;
> +		}
>  	}
>  
>  	return 1;

As pointed out by others, this should be common code. This would
definitely avoid the difference in behaviour between architectures.

	M.

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