Re: [qemu-s390x] [PATCH v3 12/16] s390-bios: Refactor virtio to run channel programs via cio

[Jason J. Herne]

On 3/5/19 7:30 AM, Cornelia Huck wrote:
> On Fri,  1 Mar 2019 13:59:32 -0500
> "Jason J. Herne" <address@hidden> wrote:
>
> > Now that we have a Channel I/O library let's modify virtio boot code to
> > make use of it for running channel programs.
> >
> > Signed-off-by: Jason J. Herne <address@hidden>
> > ---
> >   pc-bios/s390-ccw/virtio.c | 49 +++++++++++++++++++----------------------------
> >   1 file changed, 20 insertions(+), 29 deletions(-)
> >
> > diff --git a/pc-bios/s390-ccw/virtio.c b/pc-bios/s390-ccw/virtio.c
> > index aa9da72..711daf5 100644
> > --- a/pc-bios/s390-ccw/virtio.c
> > +++ b/pc-bios/s390-ccw/virtio.c
> > @@ -14,6 +14,7 @@
> >   #include "virtio.h"
> >   #include "virtio-scsi.h"
> >   #include "bswap.h"
> > +#include "helper.h"
> >   
> >   #define VRING_WAIT_REPLY_TIMEOUT 30
> >   
> > @@ -89,33 +90,20 @@ int drain_irqs(SubChannelId schid)
> >       }
> >   }
> >   
> > -static int run_ccw(VDev *vdev, int cmd, void *ptr, int len)
> > +static int run_ccw(VDev *vdev, int cmd, void *ptr, int len, bool sli)
> >   {
> >       Ccw1 ccw = {};
> > -    CmdOrb orb = {};
> > -    int r;
> > -
> > -    enable_subchannel(vdev->schid);
> > -
> > -    /* start subchannel command */
> > -    orb.fmt = 1;
> > -    orb.cpa = (u32)(long)&ccw;
> > -    orb.lpm = 0x80;
> >   
> >       ccw.cmd_code = cmd;
> >       ccw.cda = (long)ptr;
> >       ccw.count = len;
> >   
> > -    r = ssch(vdev->schid, &orb);
> > -    /*
> > -     * XXX Wait until device is done processing the CCW. For now we can
> > -     *     assume that a simple tsch will have finished the CCW processing,
> > -     *     but the architecture allows for asynchronous operation
> > -     */
> > -    if (!r) {
> > -        r = drain_irqs(vdev->schid);
> > +    if (sli) {
> > +        ccw.flags |= CCW_FLAG_SLI;
> >       }
> > -    return r;
> > +
> > +    enable_subchannel(vdev->schid);
>
> As said, maybe just move this to the main routine, instead of having to
> call this here again and again.

I can just remove this call all together, but because of the netboot case I'll need to add 
a call to enable_subchannel to virtio_is_supported() or find_net_dev().

netmain.c: main -> virtio_setup-> find_net_dev-> virtio_is_supported

Let me know if you like this idea or not. If you're okay with it, I'll queue it up for v4. 
IMHO, adding the call to find_net_dev makes more sense than virtio_is_supported.


> > +    return do_cio(vdev->schid, ptr2u32(&ccw), CCW_FMT1);
> >   }
> >   
> >   static void vring_init(VRing *vr, VqInfo *info)
>
> (...)
>
> > @@ -324,7 +314,8 @@ bool virtio_is_supported(SubChannelId schid)
> >       vdev.schid = schid;
> >       memset(&vdev.senseid, 0, sizeof(vdev.senseid));
> >       /* run sense id command */
> > -    if (run_ccw(&vdev, CCW_CMD_SENSE_ID, &vdev.senseid, sizeof(vdev.senseid))) 
> > {
> > +    if (run_ccw(&vdev, CCW_CMD_SENSE_ID, &vdev.senseid, sizeof(vdev.senseid),
> > +                true)) {
> >           return false;
> >       }
> >       if (vdev.senseid.cu_type == 0x3832) {
>
> Can't you use the new routine for obtaining the cu type here?

cu_type only returns the control unit type. This code goes on to look at the model number 
as well. In hind sight, I could have noticed this and simply structured my code to return 
the whole sense_id data structure. I'm not against making this change, but things seem 
pretty clean as they are. :)

--
-- Jason J. Herne (address@hidden)