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Date:   Tue, 4 May 2021 08:41:48 -0700
From:   Jacob Pan <jacob.jun.pan@linux.intel.com>
To:     "Tian, Kevin" <kevin.tian@intel.com>
Cc:     Jason Gunthorpe <jgg@nvidia.com>,
        Alex Williamson <alex.williamson@redhat.com>,
        "Liu, Yi L" <yi.l.liu@intel.com>,
        Auger Eric <eric.auger@redhat.com>,
        Jean-Philippe Brucker <jean-philippe@linaro.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Joerg Roedel <joro@8bytes.org>,
        Lu Baolu <baolu.lu@linux.intel.com>,
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        Johannes Weiner <hannes@cmpxchg.org>,
        Jean-Philippe Brucker <jean-philippe@linaro.com>,
        Jonathan Corbet <corbet@lwn.net>,
        "Raj, Ashok" <ashok.raj@intel.com>, "Wu, Hao" <hao.wu@intel.com>,
        "Jiang, Dave" <dave.jiang@intel.com>, jacob.jun.pan@linux.intel.com
Subject: Re: [PATCH V4 05/18] iommu/ioasid: Redefine IOASID set and
 allocation APIs
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Hi Kevin,

On Wed, 28 Apr 2021 06:34:11 +0000, "Tian, Kevin" <kevin.tian@intel.com>
wrote:

> > 
> > (also looking at ioasid.c, why do we need such a thin and odd wrapper
> > around xarray?)
> >   
> 
> I'll leave it to Jean and Jacob.
I am not sure whether you are referring to the current ioasid.c or the
changes proposed in this patchset. I added a per VM/ioasid_set
(also per /dev/ioasid fd) xarray to store guest-host PASID mapping.

The current code has a xarray for the allocators.

struct ioasid_allocator_data {
	struct ioasid_allocator_ops *ops;
	struct list_head list;
	struct list_head slist;
#define IOASID_ALLOCATOR_CUSTOM BIT(0) /* Needs framework to track results */
	unsigned long flags;
	struct xarray xa;
	struct rcu_head rcu;
};

Could you elaborate?

Thanks,

Jacob