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Date:   Thu, 2 Aug 2018 13:35:58 +0800
From:   Kenneth Lee <liguozhu@hisilicon.com>
To:     "Tian, Kevin" <kevin.tian@intel.com>
CC:     Kenneth Lee <nek.in.cn@gmail.com>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
        "Kumar, Sanjay K" <sanjay.k.kumar@intel.com>,
        Hao Fang <fanghao11@huawei.com>,
        "iommu@lists.linux-foundation.org" <iommu@lists.linux-foundation.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linuxarm@huawei.com" <linuxarm@huawei.com>,
        Alex Williamson <alex.williamson@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        "linux-crypto@vger.kernel.org" <linux-crypto@vger.kernel.org>,
        Philippe Ombredanne <pombredanne@nexb.com>,
        Zaibo Xu <xuzaibo@huawei.com>,
        "David S . Miller" <davem@davemloft.net>,
        "linux-accelerators@lists.ozlabs.org" 
        <linux-accelerators@lists.ozlabs.org>
Subject: Re: [RFC PATCH 0/7] A General Accelerator Framework, WarpDrive
Message-ID: <20180802053558.GO160746@Turing-Arch-b>
References: <20180801102221.5308-1-nek.in.cn@gmail.com>
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On Thu, Aug 02, 2018 at 04:36:52AM +0000, Tian, Kevin wrote:
> Date: Thu, 2 Aug 2018 04:36:52 +0000
> From: "Tian, Kevin" <kevin.tian@intel.com>
> To: Kenneth Lee <liguozhu@hisilicon.com>
> CC: Kenneth Lee <nek.in.cn@gmail.com>, Herbert Xu
>  <herbert@gondor.apana.org.au>, "kvm@vger.kernel.org"
>  <kvm@vger.kernel.org>, Jonathan Corbet <corbet@lwn.net>, Greg
>  Kroah-Hartman <gregkh@linuxfoundation.org>, "linux-doc@vger.kernel.org"
>  <linux-doc@vger.kernel.org>, "Kumar, Sanjay K" <sanjay.k.kumar@intel.com>,
>  Hao Fang <fanghao11@huawei.com>, "iommu@lists.linux-foundation.org"
>  <iommu@lists.linux-foundation.org>, "linux-kernel@vger.kernel.org"
>  <linux-kernel@vger.kernel.org>, "linuxarm@huawei.com"
>  <linuxarm@huawei.com>, Alex Williamson <alex.williamson@redhat.com>,
>  Thomas Gleixner <tglx@linutronix.de>, "linux-crypto@vger.kernel.org"
>  <linux-crypto@vger.kernel.org>, Philippe Ombredanne
>  <pombredanne@nexb.com>, Zaibo Xu <xuzaibo@huawei.com>, "David S . Miller"
>  <davem@davemloft.net>, "linux-accelerators@lists.ozlabs.org"
>  <linux-accelerators@lists.ozlabs.org>
> Subject: RE: [RFC PATCH 0/7] A General Accelerator Framework, WarpDrive
> Message-ID: <AADFC41AFE54684AB9EE6CBC0274A5D19129105A@SHSMSX101.ccr.corp.intel.com>
> 
> > From: Kenneth Lee
> > Sent: Thursday, August 2, 2018 11:40 AM
> > 
> > On Thu, Aug 02, 2018 at 02:59:33AM +0000, Tian, Kevin wrote:
> > > > From: Kenneth Lee
> > > > Sent: Wednesday, August 1, 2018 6:22 PM
> > > >
> > > > From: Kenneth Lee <liguozhu@hisilicon.com>
> > > >
> > > > WarpDrive is an accelerator framework to expose the hardware
> > capabilities
> > > > directly to the user space. It makes use of the exist vfio and vfio-mdev
> > > > facilities. So the user application can send request and DMA to the
> > > > hardware without interaction with the kernel. This remove the latency
> > > > of syscall and context switch.
> > > >
> > > > The patchset contains documents for the detail. Please refer to it for
> > more
> > > > information.
> > > >
> > > > This patchset is intended to be used with Jean Philippe Brucker's SVA
> > > > patch [1] (Which is also in RFC stage). But it is not mandatory. This
> > > > patchset is tested in the latest mainline kernel without the SVA patches.
> > > > So it support only one process for each accelerator.
> > >
> > > If no sharing, then why not just assigning the whole parent device to
> > > the process? IMO if SVA usage is the clear goal of your series, it
> > > might be made clearly so then Jean's series is mandatory dependency...
> > >
> > 
> > We don't know how SVA will be finally. But the feature, "make use of
> > per-PASID/substream ID IOMMU page table", should be able to be enabled
> > in the
> > kernel. So we don't want to enforce it here. After we have this serial ready,
> > it
> > can be hooked to any implementation.
> 
> "any" or "only queue-based" implementation? some devices may not
> have queue concept, e.g. GPU.

Here, "any implementation" refer to the "per PASID page table" implementatin:)

> 
> > 
> > Further more, even without "per-PASID IOMMU page table", this series has
> > its
> > value. It is not simply dedicate the whole device to the process. It "shares"
> > the device with the kernel driver. So you can support crypto and a user
> > application at the same time.
> 
> OK.
> 
> Thanks
> Kevin

-- 
			-Kenneth(Hisilicon)

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