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From: Jason Gunthorpe <jgg@nvidia.com>
To: "Raj, Ashok" <ashok.raj@intel.com>
Cc: "Jacob Pan (Jun)" <jacob.jun.pan@intel.com>,
	Alex Williamson <alex.williamson@redhat.com>,
	Jean-Philippe Brucker <jean-philippe@linaro.org>,
	Jason Wang <jasowang@redhat.com>, Liu Yi L <yi.l.liu@intel.com>,
	<eric.auger@redhat.com>, <baolu.lu@linux.intel.com>,
	<joro@8bytes.org>, <kevin.tian@intel.com>, <jun.j.tian@intel.com>,
	<yi.y.sun@intel.com>, <peterx@redhat.com>, <hao.wu@intel.com>,
	<stefanha@gmail.com>, <iommu@lists.linux-foundation.org>,
	<kvm@vger.kernel.org>, "Michael S. Tsirkin" <mst@redhat.com>,
	<jacob.jun.pan@linux.intel.com>
Subject: Re: [PATCH v7 00/16] vfio: expose virtual Shared Virtual Addressing to VMs
Date: Wed, 16 Sep 2020 14:01:13 -0300	[thread overview]
Message-ID: <20200916170113.GD3699@nvidia.com> (raw)
In-Reply-To: <20200916163343.GA76252@otc-nc-03>

On Wed, Sep 16, 2020 at 09:33:43AM -0700, Raj, Ashok wrote:
> On Wed, Sep 16, 2020 at 12:07:54PM -0300, Jason Gunthorpe wrote:
> > On Tue, Sep 15, 2020 at 05:22:26PM -0700, Jacob Pan (Jun) wrote:
> > > > If user space wants to bind page tables, create the PASID with
> > > > /dev/sva, use ioctls there to setup the page table the way it wants,
> > > > then pass the now configured PASID to a driver that can use it. 
> > > 
> > > Are we talking about bare metal SVA? 
> > 
> > What a weird term.
> 
> Glad you noticed it at v7 :-) 
> 
> Any suggestions on something less weird than 
> Shared Virtual Addressing? There is a reason why we moved from SVM
> to SVA.

SVA is fine, what is "bare metal" supposed to mean?

PASID is about constructing an arbitary DMA IOVA map for PCI-E
devices, being able to intercept device DMA faults, etc.

SVA is doing DMA IOVA 1:1 with the mm_struct CPU VA. DMA faults
trigger the same thing as CPU page faults. If is it not 1:1 then there
is no "shared". When SVA is done using PCI-E PASID it is "PASID for
SVA". Lots of existing devices already have SVA without PASID or
IOMMU, so lets not muddy the terminology.

vPASID/vIOMMU is allowing a guest to control the DMA IOVA map and
manipulate the PASIDs.

vSVA is when a guest uses a vPASID to provide SVA, not sure this is
an informative term.

This particular patch series seems to be about vPASID/vIOMMU for vfio-mdev
vs the other vPASID/vIOMMU patch which was about vPASID for vfio-pci.

> > > If so, I don't see the need for userspace to know there is a
> > > PASID. All user space need is that my current mm is bound to a
> > > device by the driver. So it can be a one-step process for user
> > > instead of two.
> > 
> > You've missed the entire point of the conversation, VDPA already needs
> > more than "my current mm is bound to a device"
> 
> You mean current version of vDPA? or a potential future version of vDPA?

Future VDPA drivers, it was made clear this was important to Intel
during the argument about VDPA as a mdev.

Jason

  reply	other threads:[~2020-09-16 20:39 UTC|newest]

Thread overview: 81+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-10 10:45 [PATCH v7 00/16] vfio: expose virtual Shared Virtual Addressing to VMs Liu Yi L
2020-09-10 10:45 ` [PATCH v7 01/16] iommu: Report domain nesting info Liu Yi L
2020-09-11 19:38   ` Alex Williamson
2020-09-10 10:45 ` [PATCH v7 02/16] iommu/smmu: Report empty " Liu Yi L
2021-01-12  6:50   ` Vivek Gautam
2021-01-12  9:21     ` Liu, Yi L
2021-01-12 11:05       ` Vivek Gautam
2021-01-13  5:56         ` Liu, Yi L
2021-01-19 10:03           ` Auger Eric
2021-01-23  8:59             ` Liu, Yi L
2021-02-12  7:14               ` Vivek Gautam
2021-02-12  9:57                 ` Auger Eric
2021-02-12 10:18                   ` Vivek Kumar Gautam
2021-02-12 11:01                     ` Vivek Kumar Gautam
2021-03-03  9:44                   ` Liu, Yi L
2020-09-10 10:45 ` [PATCH v7 03/16] vfio/type1: Report iommu nesting info to userspace Liu Yi L
2020-09-11 20:16   ` Alex Williamson
2020-09-12  8:24     ` Liu, Yi L
2020-09-10 10:45 ` [PATCH v7 04/16] vfio: Add PASID allocation/free support Liu Yi L
2020-09-11 20:54   ` Alex Williamson
2020-09-15  4:03     ` Liu, Yi L
2020-09-10 10:45 ` [PATCH v7 05/16] iommu/vt-d: Support setting ioasid set to domain Liu Yi L
2020-09-10 10:45 ` [PATCH v7 06/16] iommu/vt-d: Remove get_task_mm() in bind_gpasid() Liu Yi L
2020-09-10 10:45 ` [PATCH v7 07/16] vfio/type1: Add VFIO_IOMMU_PASID_REQUEST (alloc/free) Liu Yi L
2020-09-11 21:38   ` Alex Williamson
2020-09-10 10:45 ` [PATCH v7 08/16] iommu: Pass domain to sva_unbind_gpasid() Liu Yi L
2020-09-10 10:45 ` [PATCH v7 09/16] iommu/vt-d: Check ownership for PASIDs from user-space Liu Yi L
2020-09-10 10:45 ` [PATCH v7 10/16] vfio/type1: Support binding guest page tables to PASID Liu Yi L
2020-09-11 22:03   ` Alex Williamson
2020-09-12  6:02     ` Liu, Yi L
2020-09-10 10:45 ` [PATCH v7 11/16] vfio/type1: Allow invalidating first-level/stage IOMMU cache Liu Yi L
2020-09-10 10:45 ` [PATCH v7 12/16] vfio/type1: Add vSVA support for IOMMU-backed mdevs Liu Yi L
2020-09-10 10:45 ` [PATCH v7 13/16] vfio/pci: Expose PCIe PASID capability to guest Liu Yi L
2020-09-11 22:13   ` Alex Williamson
2020-09-12  7:17     ` Liu, Yi L
2020-09-10 10:45 ` [PATCH v7 14/16] vfio: Document dual stage control Liu Yi L
2020-09-10 10:45 ` [PATCH v7 15/16] iommu/vt-d: Only support nesting when nesting caps are consistent across iommu units Liu Yi L
2020-09-10 10:45 ` [PATCH v7 16/16] iommu/vt-d: Support reporting nesting capability info Liu Yi L
2020-09-14  4:20 ` [PATCH v7 00/16] vfio: expose virtual Shared Virtual Addressing to VMs Jason Wang
2020-09-14  8:01   ` Tian, Kevin
2020-09-14  8:57     ` Jason Wang
2020-09-14 10:38       ` Tian, Kevin
2020-09-14 11:38         ` Jason Gunthorpe
2020-09-14 13:31   ` Jean-Philippe Brucker
2020-09-14 13:47     ` Jason Gunthorpe
2020-09-14 16:22       ` Raj, Ashok
2020-09-14 16:33         ` Jason Gunthorpe
2020-09-14 16:58           ` Alex Williamson
2020-09-14 17:41             ` Jason Gunthorpe
2020-09-14 18:23               ` Alex Williamson
2020-09-14 19:00                 ` Jason Gunthorpe
2020-09-14 22:33                   ` Alex Williamson
2020-09-15 14:29                     ` Jason Gunthorpe
2020-09-16  1:19                       ` Tian, Kevin
2020-09-16  8:32                         ` Jean-Philippe Brucker
2020-09-16 14:51                           ` Jason Gunthorpe
2020-09-16 16:20                             ` Jean-Philippe Brucker
2020-09-16 16:32                               ` Jason Gunthorpe
2020-09-16 16:50                                 ` Auger Eric
2020-09-16 14:44                         ` Jason Gunthorpe
2020-09-17  6:01                           ` Tian, Kevin
     [not found]                   ` <20200914224438.GA65940@otc-nc-03>
2020-09-15 11:33                     ` Jason Gunthorpe
2020-09-15 18:11                       ` Raj, Ashok
2020-09-15 18:45                         ` Jason Gunthorpe
2020-09-15 19:26                           ` Raj, Ashok
2020-09-15 23:45                             ` Jason Gunthorpe
2020-09-16  2:33                             ` Jason Wang
2020-09-15 22:08                           ` Jacob Pan
2020-09-15 23:51                             ` Jason Gunthorpe
     [not found]                               ` <20200915171319.00003f59@linux.intel.com>
2020-09-16  1:46                                 ` Lu Baolu
2020-09-16 15:07                                 ` Jason Gunthorpe
2020-09-16 16:33                                   ` Raj, Ashok
2020-09-16 17:01                                     ` Jason Gunthorpe [this message]
2020-09-16 18:21                                       ` Jacob Pan (Jun)
2020-09-16 18:38                                         ` Jason Gunthorpe
2020-09-16 23:09                                           ` Jacob Pan (Jun)
2020-09-17  3:53                                             ` Jason Wang
2020-09-17 17:31                                               ` Jason Gunthorpe
2020-09-17 18:17                                               ` Jacob Pan (Jun)
2020-09-18  3:58                                                 ` Jason Wang
2020-09-16  2:29     ` Jason Wang

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