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From:   "Tian, Kevin" <kevin.tian@intel.com>
To:     Lu Baolu <baolu.lu@linux.intel.com>,
        Joerg Roedel <joro@8bytes.org>,
        "Will Deacon" <will@kernel.org>,
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CC:     "Liu, Yi L" <yi.l.liu@intel.com>,
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        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
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Subject: RE: [PATCH 9/9] iommu: Use fault cookie to store iopf_param
Thread-Topic: [PATCH 9/9] iommu: Use fault cookie to store iopf_param
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Date:   Tue, 11 Jul 2023 06:26:43 +0000
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> From: Lu Baolu <baolu.lu@linux.intel.com>
> Sent: Tuesday, July 11, 2023 9:07 AM
>=20
> Remove the static iopf_param pointer from struct iommu_fault_param to
> save memory.

why is there memory saving? you replace a single pointer with a xarray now.=
..

> @@ -303,16 +303,27 @@ int iopf_queue_add_device(struct iopf_queue
> *queue, struct device *dev)
>=20
>  	mutex_lock(&queue->lock);
>  	mutex_lock(&param->lock);
> -	if (!param->iopf_param) {
> -		list_add(&iopf_param->queue_list, &queue->devices);
> -		param->iopf_param =3D iopf_param;
> -		ret =3D 0;
> +	curr =3D iommu_set_device_fault_cookie(dev, 0, iopf_param);
> +	if (IS_ERR(curr)) {
> +		ret =3D PTR_ERR(curr);
> +		goto err_free;
>  	}

So although the new xarray is called a per-pasid storage, here only
slot#0 is used for sva which includes a list containing partial req's
for many pasid's. It doesn't sound clean...