From: Alex Williamson <alex.williamson@redhat.com>
To: "Chen, Xiaoguang" <xiaoguang.chen@intel.com>
Cc: "Tian, Kevin" <kevin.tian@intel.com>,
"intel-gfx@lists.freedesktop.org"
<intel-gfx@lists.freedesktop.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"zhenyuw@linux.intel.com" <zhenyuw@linux.intel.com>,
"Lv, Zhiyuan" <zhiyuan.lv@intel.com>,
"intel-gvt-dev@lists.freedesktop.org"
<intel-gvt-dev@lists.freedesktop.org>,
"Wang, Zhi A" <zhi.a.wang@intel.com>,
Gerd Hoffmann <kraxel@redhat.com>
Subject: Re: [RFC PATCH 6/6] drm/i915/gvt: support QEMU getting the dmabuf
Date: Thu, 4 May 2017 10:08:33 -0600 [thread overview]
Message-ID: <20170504100833.199bc8ba@t450s.home> (raw)
In-Reply-To: <DD379D741F77464281CE7ED1CD7C12DE6FC93698@SHSMSX101.ccr.corp.intel.com>
On Thu, 4 May 2017 03:09:40 +0000
"Chen, Xiaoguang" <xiaoguang.chen@intel.com> wrote:
> Hi Alex, do you have any comments for this interface?
>
> >-----Original Message-----
> >From: intel-gvt-dev [mailto:intel-gvt-dev-bounces@lists.freedesktop.org] On
> >Behalf Of Chen, Xiaoguang
> >Sent: Wednesday, May 03, 2017 9:39 AM
> >To: Gerd Hoffmann <kraxel@redhat.com>
> >Cc: Tian, Kevin <kevin.tian@intel.com>; intel-gfx@lists.freedesktop.org; linux-
> >kernel@vger.kernel.org; zhenyuw@linux.intel.com; alex.williamson@redhat.com;
> >Lv, Zhiyuan <zhiyuan.lv@intel.com>; intel-gvt-dev@lists.freedesktop.org; Wang,
> >Zhi A <zhi.a.wang@intel.com>
> >Subject: RE: [RFC PATCH 6/6] drm/i915/gvt: support QEMU getting the dmabuf
> >
> >
> >
> >>-----Original Message-----
> >>From: Gerd Hoffmann [mailto:kraxel@redhat.com]
> >>Sent: Tuesday, May 02, 2017 5:51 PM
> >>To: Chen, Xiaoguang <xiaoguang.chen@intel.com>
> >>Cc: alex.williamson@redhat.com; intel-gfx@lists.freedesktop.org;
> >>intel-gvt- dev@lists.freedesktop.org; Wang, Zhi A
> >><zhi.a.wang@intel.com>; zhenyuw@linux.intel.com;
> >>linux-kernel@vger.kernel.org; Lv, Zhiyuan <zhiyuan.lv@intel.com>; Tian,
> >>Kevin <kevin.tian@intel.com>
> >>Subject: Re: [RFC PATCH 6/6] drm/i915/gvt: support QEMU getting the
> >>dmabuf
> >>
> >>On Fr, 2017-04-28 at 17:35 +0800, Xiaoguang Chen wrote:
> >>> +static size_t intel_vgpu_reg_rw_gvtg(struct intel_vgpu *vgpu, char
> >>> *buf,
> >>> + size_t count, loff_t *ppos, bool iswrite) {
> >>> + unsigned int i = VFIO_PCI_OFFSET_TO_INDEX(*ppos) -
> >>> + VFIO_PCI_NUM_REGIONS;
> >>> + loff_t pos = *ppos & VFIO_PCI_OFFSET_MASK;
> >>> + int fd;
> >>> +
> >>> + if (pos >= vgpu->vdev.region[i].size || iswrite) {
> >>> + gvt_vgpu_err("invalid op or offset for Intel vgpu fd
> >>> region\n");
> >>> + return -EINVAL;
> >>> + }
> >>> +
> >>> + fd = anon_inode_getfd("gvtg", &intel_vgpu_gvtg_ops, vgpu,
> >>> + O_RDWR | O_CLOEXEC);
> >>> + if (fd < 0) {
> >>> + gvt_vgpu_err("create intel vgpu fd failed:%d\n", fd);
> >>> + return -EINVAL;
> >>> + }
> >>> +
> >>> + count = min(count, (size_t)(vgpu->vdev.region[i].size - pos));
> >>> + memcpy(buf, &fd, count);
> >>> +
> >>> + return count;
> >>> +}
> >>
> >>Hmm, that looks like a rather strange way to return a file descriptor.
> >>
> >>What is the reason to not use ioctls on the vfio file handle, like
> >>older version of these patches did?
> >If I understood correctly that Alex prefer not to change the ioctls on the vfio file
> >handle like the old version.
> >So I used this way the smallest change to general vfio framework only adding a
> >subregion definition.
I think I was hoping we could avoid a separate file descriptor
altogether and use a vfio region instead. However, it was explained
previously why this really needs to be a separate fd and I agree that
using a region to expose an fd is really awkward. If we're going to
have a separate fd, let's use a device specific ioctl to get it.
Thanks,
Alex
next prev parent reply other threads:[~2017-05-04 16:08 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-28 9:35 [RFC PATCH 0/6] drm/i915/gvt: dma-buf support for GVT-g Xiaoguang Chen
2017-04-28 9:35 ` [RFC PATCH 1/6] drm/i915/gvt: extend the GVT-g architecture to support vfio device region Xiaoguang Chen
2017-04-28 9:35 ` [RFC PATCH 2/6] drm/i915/gvt: OpRegion support for GVT-g Xiaoguang Chen
2017-04-28 9:35 ` [RFC PATCH 3/6] drm/i915/gvt: framebuffer decoder " Xiaoguang Chen
2017-04-28 9:35 ` [RFC PATCH 4/6] drm/i915: export i915 dmabuf_ops Xiaoguang Chen
2017-04-28 9:35 ` [RFC PATCH 5/6] drm/i915/gvt: dmabuf support for GVT-g Xiaoguang Chen
2017-04-28 10:08 ` [Intel-gfx] " Chris Wilson
2017-05-02 7:40 ` Chen, Xiaoguang
2017-05-04 3:12 ` Chen, Xiaoguang
2017-05-02 9:37 ` Gerd Hoffmann
2017-04-28 9:35 ` [RFC PATCH 6/6] drm/i915/gvt: support QEMU getting the dmabuf Xiaoguang Chen
2017-05-02 9:50 ` Gerd Hoffmann
2017-05-03 1:39 ` Chen, Xiaoguang
2017-05-04 3:09 ` Chen, Xiaoguang
2017-05-04 16:08 ` Alex Williamson [this message]
2017-05-05 6:55 ` Gerd Hoffmann
2017-05-05 15:11 ` Alex Williamson
2017-05-11 8:45 ` Chen, Xiaoguang
2017-05-11 13:27 ` Gerd Hoffmann
2017-05-11 15:45 ` Alex Williamson
2017-05-12 2:12 ` Chen, Xiaoguang
2017-05-12 2:58 ` Alex Williamson
2017-05-12 3:52 ` Chen, Xiaoguang
2017-05-12 9:12 ` Gerd Hoffmann
2017-05-12 16:38 ` Alex Williamson
2017-05-15 3:36 ` Chen, Xiaoguang
2017-05-15 17:44 ` Alex Williamson
2017-05-16 10:16 ` Chen, Xiaoguang
2017-05-17 21:43 ` Alex Williamson
2017-05-18 1:51 ` Chen, Xiaoguang
2017-05-18 14:56 ` Alex Williamson
2017-05-19 6:23 ` Chen, Xiaoguang
2017-05-19 8:04 ` Gerd Hoffmann
2017-05-19 8:17 ` Chen, Xiaoguang
2017-05-19 8:57 ` Gerd Hoffmann
2017-05-19 9:14 ` Chen, Xiaoguang
2017-05-19 10:51 ` Gerd Hoffmann
2017-05-18 6:22 ` Gerd Hoffmann
2017-05-12 6:56 ` Chen, Xiaoguang
2017-05-12 17:04 ` Alex Williamson
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