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Re: [Qemu-devel] [RFC 3/3] vhost-user: support programming VFIO group in
From: |
Michael S. Tsirkin |
Subject: |
Re: [Qemu-devel] [RFC 3/3] vhost-user: support programming VFIO group in master |
Date: |
Wed, 12 Sep 2018 12:14:44 -0400 |
On Wed, Sep 12, 2018 at 04:04:00PM +0800, Tiwei Bie wrote:
> On Mon, Jul 30, 2018 at 12:30:58PM +0300, Michael S. Tsirkin wrote:
> [...]
> >
> > I generally wonder how are restarts of the backend handled
> > with this approach: closing the VFIO device tends to reset
> > the whole device.
>
> Hi Michael,
>
> I missed this comment previously.. This is a good point!
> In this RFC, before sending the VFIO group fd to QEMU,
> backend needs to close the VFIO device and unset the VFIO
> container first. Otherwise, QEMU won't be able to set the
> VFIO container for the VFIO group.
>
> Another option is to share the container fd instead of
> the group fd to QEMU. In this case, backend won't need
> to close any fd. But there is one problem that, it's
> hard to unmap the old mappings, especially when QEMU
> crashes.
What are these old mappings and who creates them?
If you want to just reset everything the way it was
on open, surely it would be easy to add such a reset ioctl.
> Do you have any suggestions? Thanks!
>
> Best regards,
> Tiwei Bie
Donnu. Alex, any thoughts? Which approach would you prefer?
--
MST
- Re: [Qemu-devel] [RFC 3/3] vhost-user: support programming VFIO group in master, Tiwei Bie, 2018/09/12
- Re: [Qemu-devel] [RFC 3/3] vhost-user: support programming VFIO group in master,
Michael S. Tsirkin <=
- Re: [Qemu-devel] [RFC 3/3] vhost-user: support programming VFIO group in master, Alex Williamson, 2018/09/12
- Re: [Qemu-devel] [RFC 3/3] vhost-user: support programming VFIO group in master, Michael S. Tsirkin, 2018/09/12
- Re: [Qemu-devel] [RFC 3/3] vhost-user: support programming VFIO group in master, Alex Williamson, 2018/09/12
- Re: [Qemu-devel] [RFC 3/3] vhost-user: support programming VFIO group in master, Michael S. Tsirkin, 2018/09/12
- Re: [Qemu-devel] [RFC 3/3] vhost-user: support programming VFIO group in master, Alex Williamson, 2018/09/12
- Re: [Qemu-devel] [RFC 3/3] vhost-user: support programming VFIO group in master, Tian, Kevin, 2018/09/13