Re: [Intel-gfx] [PATCH v2 0/9] Move vfio_ccw to the new mdev API

Eric Farman
2021-09-13T20:47:10Z

On Mon, 2021-09-13 at 16:24 -0300, Jason Gunthorpe wrote:
> On Mon, Sep 13, 2021 at 01:40:34PM -0400, Eric Farman wrote:
> > On Thu, 2021-09-09 at 16:38 -0300, Jason Gunthorpe wrote:
> > > This addresses Cornelia's remark on the earlier patch that ccw
> > > has a
> > > confusing lifecycle. While it doesn't seem like the original
> > > attempt
> > > was
> > > functionally wrong, the result can be made better with a lot of
> > > further
> > > work.
> >
> > I thought I'd take a stab at seeing how this works with the
> > hardware
> > before looking at the code much. git couldn't apply patches 1, 6,
> > or 9
> > to 5.15-rc1, but I was able to hand-fit them into place.
>
> Oh? Thats odd, I had no remarks from git when rebasing onto
> v5.15-rc1..
>
> Maybe this is a situation where you need "b4 am --prep-3way" ...

Ah, that does indeed help, thanks. Still missing the vfio-ap patch
that's elsewhere on the list, but I'm not caring about that at the
moment.

>
> > [ 64.585462] Call Trace:
> > [ 64.585464] [<0000000000000002>] 0x2
> > [ 64.585467] ([<000003ff80179d74>] vfio_ccw_mdev_ioctl+0x84/0x318
> > [vfio_ccw])
> > [ 64.585476] [<00000000bb7adda6>] __s390x_sys_ioctl+0xbe/0x100
> > [ 64.585481] [<00000000bbfbf5e4>] __do_syscall+0x1bc/0x1e8
> > [ 64.585488] [<00000000bbfcc8d8>] system_call+0x78/0xa0
>
> I think it is this:
>
> diff --git a/drivers/s390/cio/vfio_ccw_fsm.c
> b/drivers/s390/cio/vfio_ccw_fsm.c
> index df1490943b20ec..5ea392959c0711 100644
> --- a/drivers/s390/cio/vfio_ccw_fsm.c
> +++ b/drivers/s390/cio/vfio_ccw_fsm.c
> @@ -441,6 +441,7 @@ fsm_func_t
> *vfio_ccw_jumptable[NR_VFIO_CCW_STATES][NR_VFIO_CCW_EVENTS] = {
> [VFIO_CCW_EVENT_IO_REQ] = fsm_io_error,
> [VFIO_CCW_EVENT_ASYNC_REQ] = fsm_async_error,
> [VFIO_CCW_EVENT_INTERRUPT] = fsm_disabled_irq,
> + [VFIO_CCW_EVENT_OPEN] = fsm_nop,
> [VFIO_CCW_EVENT_CLOSE] = fsm_nop,
> },
> [VFIO_CCW_STATE_CLOSED] = {
>
> I rebased it and fixed it up here:
>
> https://github.com/jgunthorpe/linux/tree/vfio_ccw
>
> Can you try again?

That does address the crash, but then why is it processing a BROKEN
event? Seems problematic. All the configuration works fine, but the
devices get ripped away once a guest is started that wants to open/use
them.

So, there's more problems to figure out.

Eric

>
> Thanks,
> Jason