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From: Christoph Hellwig <hch@lst.de>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: "Wang, Zhi A" <zhi.a.wang@intel.com>,
	Gerd Hoffmann <kraxel@redhat.com>,
	Greg KH <gregkh@linuxfoundation.org>,
	Christoph Hellwig <hch@lst.de>,
	Jani Nikula <jani.nikula@linux.intel.com>,
	Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
	"Vivi, Rodrigo" <rodrigo.vivi@intel.com>,
	Zhenyu Wang <zhenyuw@linux.intel.com>,
	"intel-gfx@lists.freedesktop.org"
	<intel-gfx@lists.freedesktop.org>,
	"intel-gvt-dev@lists.freedesktop.org" 
	<intel-gvt-dev@lists.freedesktop.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"dri-devel@lists.freedesktop.org"
	<dri-devel@lists.freedesktop.org>
Subject: Re: refactor the i915 GVT support
Date: Thu, 29 Jul 2021 09:20:22 +0200	[thread overview]
Message-ID: <20210729072022.GB31896@lst.de> (raw)
In-Reply-To: <20210728175925.GU1721383@nvidia.com>

On Wed, Jul 28, 2021 at 02:59:25PM -0300, Jason Gunthorpe wrote:
> On Wed, Jul 28, 2021 at 01:38:58PM +0000, Wang, Zhi A wrote:
> 
> > I guess those APIs you were talking about are KVM-only. For other
> > hypervisors, e.g. Xen, ARCN cannot use the APIs you mentioned. Not
> > sure if you have already noticed that VFIO is KVM-only right now.
> 
> There is very little hard connection between VFIO and KVM, so no, I
> don't think that is completely true.

The only connection is the SET_KVM notifier as far as I can tell.
Which is used by a total of two drivers, including i915/gvt.  That
being said gvt does not only use vfio, but also does quite a few
direct cals to KVM.

> In an event, an in-tree version of other hypervisor support for GVT
> needs to go through enabling VFIO support so that the existing API
> multiplexers we have can be used properly, not adding a shim layer
> trying to recreate VFIO inside a GPU driver.

Yes.  And if we go back to actually looking at the series a lot of
it just removes entirely pointless indirect calls that go to generic
code and not even the kvm code, or questionable data structure designs.
If we were to support another upstream hypervisor we'd just need to
union a few fields in struct intel_gpu and maybe introduce a few
methods.  Preferably in a way that avoids expensive indirect calls
in the fast path.

  reply	other threads:[~2021-07-29  7:20 UTC|newest]

Thread overview: 60+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-21 15:53 Christoph Hellwig
2021-07-21 15:53 ` [PATCH 01/21] drm/i915/gvt: integrate into the main Makefile Christoph Hellwig
2021-08-03  9:27   ` Zhenyu Wang
2021-07-21 15:53 ` [PATCH 02/21] drm/i915/gvt: remove module refcounting in intel_gvt_{,un}register_hypervisor Christoph Hellwig
2021-07-21 15:53 ` [PATCH 03/21] drm/i915/gvt: remove enum hypervisor_type Christoph Hellwig
2021-07-21 15:53 ` [PATCH 04/21] drm/i915/gvt: move the gvt code into kvmgt.ko Christoph Hellwig
2021-08-09 11:29   ` Joonas Lahtinen
2021-08-09 14:29     ` Christoph Hellwig
2021-07-21 15:53 ` [PATCH 05/21] drm/i915/gvt: remove intel_gvt_ops Christoph Hellwig
2021-07-21 15:53 ` [PATCH 06/21] drm/i915/gvt: remove the map_gfn_to_mfn and set_trap_area ops Christoph Hellwig
2021-07-21 15:53 ` [PATCH 07/21] drm/i915/gvt: remove the unused from_virt_to_mfn op Christoph Hellwig
2021-07-21 15:53 ` [PATCH 08/21] drm/i915/gvt: merge struct kvmgt_vdev into struct intel_vgpu Christoph Hellwig
2021-07-21 15:53 ` [PATCH 09/21] drm/i915/gvt: merge struct kvmgt_guest_info into strut intel_vgpu Christoph Hellwig
2021-07-21 15:53 ` [PATCH 10/21] drm/i915/gvt: remove vgpu->handle Christoph Hellwig
2021-07-21 15:53 ` [PATCH 11/21] drm/i915/gvt: devirtualize ->{read,write}_gpa Christoph Hellwig
2021-07-21 15:53 ` [PATCH 12/21] drm/i915/gvt: devirtualize ->{get,put}_vfio_device Christoph Hellwig
2021-07-21 15:53 ` [PATCH 13/21] drm/i915/gvt: devirtualize ->set_edid and ->set_opregion Christoph Hellwig
2021-07-21 15:53 ` [PATCH 14/21] drm/i915/gvt: devirtualize ->detach_vgpu Christoph Hellwig
2021-07-21 15:53 ` [PATCH 15/21] drm/i915/gvt: devirtualize ->inject_msi Christoph Hellwig
2021-07-21 15:53 ` [PATCH 16/21] drm/i915/gvt: devirtualize ->is_valid_gfn Christoph Hellwig
2021-07-21 15:53 ` [PATCH 17/21] drm/i915/gvt: devirtualize ->gfn_to_mfn Christoph Hellwig
2021-07-21 15:53 ` [PATCH 18/21] drm/i915/gvt: devirtualize ->{enable,disable}_page_track Christoph Hellwig
2021-07-21 15:53 ` [PATCH 19/21] drm/i915/gvt: devirtualize ->dma_{,un}map_guest_page Christoph Hellwig
2021-07-21 15:53 ` [PATCH 20/21] drm/i915/gvt: devirtualize dma_pin_guest_page Christoph Hellwig
2021-07-21 15:53 ` [PATCH 21/21] drm/i915/gvt: remove struct intel_gvt_mpt Christoph Hellwig
2021-07-22  9:45 ` refactor the i915 GVT support Zhenyu Wang
2021-07-22 12:55   ` Christoph Hellwig
2021-07-22 10:49 ` Wang, Zhi A
2021-07-22 11:26   ` Gerd Hoffmann
2021-07-27 12:12     ` Jason Gunthorpe
2021-07-28 13:38       ` Wang, Zhi A
2021-07-28 13:43         ` Greg KH
2021-07-28 17:59         ` Jason Gunthorpe
2021-07-29  7:20           ` Christoph Hellwig [this message]
2021-07-29  7:30             ` [Intel-gfx] " Daniel Vetter
2021-08-03  9:43             ` Zhenyu Wang
2021-08-03 14:30               ` Jason Gunthorpe
2021-08-04  5:26                 ` Zhenyu Wang
2021-08-16 17:34                   ` Christoph Hellwig
2021-08-17  1:08                     ` Zhenyu Wang
2021-08-17  5:22                       ` Zhenyu Wang
2021-08-19  8:29                         ` Zhenyu Wang
2021-08-19 14:43                           ` Joonas Lahtinen
2021-08-26  6:04                             ` Zhenyu Wang
2021-08-20 14:17                           ` Christoph Hellwig
2021-08-20 19:56                             ` Luis Chamberlain
2021-08-26  6:12                               ` Zhenyu Wang
2021-09-28  7:41                                 ` Wang, Zhi A
2021-09-28 14:00                                   ` Luis Chamberlain
2021-09-28 14:35                                     ` Wang, Zhi A
2021-09-28 15:05                                       ` Jason Gunthorpe
2021-09-29 18:27                                         ` Wang, Zhi A
2021-09-29 18:55                                           ` Jason Gunthorpe
2021-10-01 13:01                                             ` Wang, Zhi A
2021-10-05  7:33                                               ` Wang, Zhi A
2021-09-30  5:24                                           ` Christoph Hellwig
2021-08-26  6:08                             ` Zhenyu Wang
2021-08-04  5:40                 ` Christoph Hellwig
2021-07-29  8:19           ` Wang, Zhi A
2021-07-22 13:16   ` Greg KH

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