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Re: [RFC PATCH 6/6] drm/i915/gvt: support QEMU getting the dmabuf

From Gerd Hoffmann <kraxel@redhat.com>
Newsgroups linux.kernel
Subject Re: [RFC PATCH 6/6] drm/i915/gvt: support QEMU getting the dmabuf
Date 2017-05-02 12:00 +0200
Message-ID <tCCL7-4Uk-3@gated-at.bofh.it> (permalink)
References <tBaHf-5yJ-7@gated-at.bofh.it> <tBaHf-5yJ-5@gated-at.bofh.it>
Organization linux.* mail to news gateway

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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?

cheers,
  Gerd

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Thread

[RFC PATCH 6/6] drm/i915/gvt: support QEMU getting the dmabuf Xiaoguang Chen <xiaoguang.chen@intel.com> - 2017-04-28 11:50 +0200
  Re: [RFC PATCH 6/6] drm/i915/gvt: support QEMU getting the dmabuf Gerd Hoffmann <kraxel@redhat.com> - 2017-05-02 12:00 +0200
    RE: [RFC PATCH 6/6] drm/i915/gvt: support QEMU getting the dmabuf "Chen, Xiaoguang" <xiaoguang.chen@intel.com> - 2017-05-03 03:50 +0200
      RE: [RFC PATCH 6/6] drm/i915/gvt: support QEMU getting the dmabuf "Chen, Xiaoguang" <xiaoguang.chen@intel.com> - 2017-05-04 05:20 +0200
        Re: [RFC PATCH 6/6] drm/i915/gvt: support QEMU getting the dmabuf Alex Williamson <alex.williamson@redhat.com> - 2017-05-04 18:10 +0200
          Re: [RFC PATCH 6/6] drm/i915/gvt: support QEMU getting the dmabuf Gerd Hoffmann <kraxel@redhat.com> - 2017-05-05 09:00 +0200
            Re: [RFC PATCH 6/6] drm/i915/gvt: support QEMU getting the dmabuf Alex Williamson <alex.williamson@redhat.com> - 2017-05-05 17:20 +0200
              RE: [RFC PATCH 6/6] drm/i915/gvt: support QEMU getting the dmabuf "Chen, Xiaoguang" <xiaoguang.chen@intel.com> - 2017-05-11 10:50 +0200
                Re: [RFC PATCH 6/6] drm/i915/gvt: support QEMU getting the dmabuf Gerd Hoffmann <kraxel@redhat.com> - 2017-05-11 15:30 +0200
                Re: [RFC PATCH 6/6] drm/i915/gvt: support QEMU getting the dmabuf Alex Williamson <alex.williamson@redhat.com> - 2017-05-11 17:50 +0200

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