On Thu, 4 May 2017 03:09:40 +0000 "Chen, Xiaoguang" <xiaoguang.chen@xxxxxxxxx> wrote: > Hi Alex, do you have any comments for this interface? > > >-----Original Message----- > >From: intel-gvt-dev [mailto:intel-gvt-dev-bounces@xxxxxxxxxxxxxxxxxxxxx] On > >Behalf Of Chen, Xiaoguang > >Sent: Wednesday, May 03, 2017 9:39 AM > >To: Gerd Hoffmann <kraxel@xxxxxxxxxx> > >Cc: Tian, Kevin <kevin.tian@xxxxxxxxx>; intel-gfx@xxxxxxxxxxxxxxxxxxxxx; linux- > >kernel@xxxxxxxxxxxxxxx; zhenyuw@xxxxxxxxxxxxxxx; alex.williamson@xxxxxxxxxx; > >Lv, Zhiyuan <zhiyuan.lv@xxxxxxxxx>; intel-gvt-dev@xxxxxxxxxxxxxxxxxxxxx; Wang, > >Zhi A <zhi.a.wang@xxxxxxxxx> > >Subject: RE: [RFC PATCH 6/6] drm/i915/gvt: support QEMU getting the dmabuf > > > > > > > >>-----Original Message----- > >>From: Gerd Hoffmann [mailto:kraxel@xxxxxxxxxx] > >>Sent: Tuesday, May 02, 2017 5:51 PM > >>To: Chen, Xiaoguang <xiaoguang.chen@xxxxxxxxx> > >>Cc: alex.williamson@xxxxxxxxxx; intel-gfx@xxxxxxxxxxxxxxxxxxxxx; > >>intel-gvt- dev@xxxxxxxxxxxxxxxxxxxxx; Wang, Zhi A > >><zhi.a.wang@xxxxxxxxx>; zhenyuw@xxxxxxxxxxxxxxx; > >>linux-kernel@xxxxxxxxxxxxxxx; Lv, Zhiyuan <zhiyuan.lv@xxxxxxxxx>; Tian, > >>Kevin <kevin.tian@xxxxxxxxx> > >>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 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
