From mboxrd@z Thu Jan  1 00:00:00 1970
From: xuzaibo@huawei.com (Xu Zaibo)
Date: Tue, 4 Sep 2018 10:12:37 +0800
Subject: [PATCH v2 13/40] vfio: Add support for Shared Virtual Addressing
In-Reply-To: <3a961aff-e830-64bb-b6a9-14e08de1abf5@arm.com>
References: <20180511190641.23008-1-jean-philippe.brucker@arm.com>
 <20180511190641.23008-14-jean-philippe.brucker@arm.com>
 <5B83B11E.7010807@huawei.com> <1d5b6529-4e5a-723c-3f1b-dd5a9adb490c@arm.com>
 <5B89F818.7060300@huawei.com> <3a961aff-e830-64bb-b6a9-14e08de1abf5@arm.com>
Message-ID: <5B8DEA15.7020404@huawei.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org



On 2018/9/3 18:34, Jean-Philippe Brucker wrote:
> On 01/09/18 03:23, Xu Zaibo wrote:
>> As one application takes a whole function while using VFIO-PCI, why do
>> the application and the
>> function need to enable PASID capability? (Since just one I/O page table
>> is enough for them.)
> At the moment the series doesn't provide support for SVA without PASID
> (on the I/O page fault path, 08/40). In addition the BIND ioctl could be
> used by the owner application to bind other processes (slaves) and
> perform sub-assignment. But that feature is incomplete because we don't
> send stop_pasid notification to the owner when a slave dies.
>
So, Could I understand like this?

     1. While the series are finished well, VFIO-PCI device can be held 
by only one process
         through binding IOCTL command without PASID (without PASID 
being exposed user space).

     2. While using VFIO-PCI device to support multiple processes with 
SVA series, a primary
         process with multiple secondary processes must be deployed just 
like DPDK(https://www.dpdk.org/).
         And, the PASID still has to be exposed to user land.


Thanks,
Zaibo

.