Re: [RFC PATCH 16/42] iommufd: Enable device feature IOPF during device attachment to KVM HWPT

[Jason Gunthorpe]

On Sat, Dec 02, 2023 at 05:23:11PM +0800, Yan Zhao wrote:
> Enable device feature IOPF during device attachment to KVM HWPT and abort
> the attachment if feature enabling is failed.
> 
> "pin" is not done by KVM HWPT. If VMM wants to create KVM HWPT, it must
> know that all devices attached to this HWPT support IOPF so that pin-all
> is skipped.
> 
> Signed-off-by: Yan Zhao <yan.y.zhao@xxxxxxxxx>
> ---
>  drivers/iommu/iommufd/device.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/drivers/iommu/iommufd/device.c b/drivers/iommu/iommufd/device.c
> index 83af6b7e2784b..4ea447e052ce1 100644
> --- a/drivers/iommu/iommufd/device.c
> +++ b/drivers/iommu/iommufd/device.c
> @@ -381,10 +381,26 @@ int iommufd_hw_pagetable_attach(struct iommufd_hw_pagetable *hwpt,
>  			goto err_unresv;
>  		idev->igroup->hwpt = hwpt;
>  	}
> +	if (hwpt_is_kvm(hwpt)) {
> +		/*
> +		 * Feature IOPF requires ats is enabled which is true only
> +		 * after device is attached to iommu domain.
> +		 * So enable dev feature IOPF after iommu_attach_group().
> +		 * -EBUSY will be returned if feature IOPF is already on.
> +		 */
> +		rc = iommu_dev_enable_feature(idev->dev, IOMMU_DEV_FEAT_IOPF);
> +		if (rc && rc != -EBUSY)
> +			goto err_detach;

I would like to remove IOMMU_DEV_FEAT_IOPF completely please

Jason