[RFC PATCH 0/7] A General Accelerator Framework, WarpDrive
liguozhu at hisilicon.com
Thu Aug 2 15:35:58 AEST 2018
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 at intel.com>
> To: Kenneth Lee <liguozhu at hisilicon.com>
> CC: Kenneth Lee <nek.in.cn at gmail.com>, Herbert Xu
> <herbert at gondor.apana.org.au>, "kvm at vger.kernel.org"
> <kvm at vger.kernel.org>, Jonathan Corbet <corbet at lwn.net>, Greg
> Kroah-Hartman <gregkh at linuxfoundation.org>, "linux-doc at vger.kernel.org"
> <linux-doc at vger.kernel.org>, "Kumar, Sanjay K" <sanjay.k.kumar at intel.com>,
> Hao Fang <fanghao11 at huawei.com>, "iommu at lists.linux-foundation.org"
> <iommu at lists.linux-foundation.org>, "linux-kernel at vger.kernel.org"
> <linux-kernel at vger.kernel.org>, "linuxarm at huawei.com"
> <linuxarm at huawei.com>, Alex Williamson <alex.williamson at redhat.com>,
> Thomas Gleixner <tglx at linutronix.de>, "linux-crypto at vger.kernel.org"
> <linux-crypto at vger.kernel.org>, Philippe Ombredanne
> <pombredanne at nexb.com>, Zaibo Xu <xuzaibo at huawei.com>, "David S . Miller"
> <davem at davemloft.net>, "linux-accelerators at lists.ozlabs.org"
> <linux-accelerators at lists.ozlabs.org>
> Subject: RE: [RFC PATCH 0/7] A General Accelerator Framework, WarpDrive
> Message-ID: <AADFC41AFE54684AB9EE6CBC0274A5D19129105A at 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 at 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  (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.
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