Date:   Mon, 13 Feb 2023 11:11:52 -0800
From:   Jacob Pan <jacob.jun.pan@linux.intel.com>
To:     Jason Gunthorpe <jgg@nvidia.com>
Cc:     Jean-Philippe Brucker <jean-philippe@linaro.org>,
        LKML <linux-kernel@vger.kernel.org>, iommu@lists.linux.dev,
        Lu Baolu <baolu.lu@linux.intel.com>,
        Joerg Roedel <joro@8bytes.org>,
        Jean-Philippe Brucker <jean-philippe@linaro.com>,
        Robin Murphy <robin.murphy@arm.com>,
        David Woodhouse <dwmw2@infradead.org>,
        Raj Ashok <ashok.raj@intel.com>,
        "Tian, Kevin" <kevin.tian@intel.com>, Yi Liu <yi.l.liu@intel.com>,
        jacob.jun.pan@linux.intel.com
Subject: Re: [PATCH 2/2] iommu/ioasid: Remove custom IOASID allocator
Message-ID: <20230213111152.5ecf734b@jacob-builder>
In-Reply-To: <Y+pkL5b6mGv40nZy@nvidia.com>
References: <20230210230206.3160144-1-jacob.jun.pan@linux.intel.com>
        <20230210230206.3160144-3-jacob.jun.pan@linux.intel.com>
        <Y+pjTR80bnl9rMK1@myrica>
        <Y+pkL5b6mGv40nZy@nvidia.com>
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Hi Jason,

On Mon, 13 Feb 2023 12:24:15 -0400, Jason Gunthorpe <jgg@nvidia.com> wrote:

> > We could also merge ioasid.c into iommu-sva.c at this point, since I
> > haven't seen any interest for having multiple IOASID sets on Arm, but
> > I'm not sure what the current plan is for vSVA on x86.  
> 
> Once the customer allocator is removed this is bascially a thin
> wrapper around xarray
> 
> So anything that needs multiple pasid spaces should just create it on
> its own directly with xarray
> 
Just wanted to double check that for devices on VT-d platforms that support
both SVA and DMA API with PASID, we will still need a single global pasid
space (due to IOTLB tagging). So this is not the "multiple pasid spaces"
case here, right?

As I replied to Jean as well, we could use the ioasid_set to separate SVA
and DMA API PASIDs.

Thanks,

Jacob