Re: [PULL v3 23/32] s390x/pci: Add routine to get the vfio dma available count

[Cornelia Huck <cohuck@redhat.com>]

On Tue, 3 Nov 2020 06:49:13 +0100
Philippe Mathieu-Daudé <philmd@redhat.com> wrote:

> Hi Matthew,
> 
> On 11/1/20 10:02 PM, Alex Williamson wrote:
> > From: Matthew Rosato <mjrosato@linux.ibm.com>
> > 
> > Create new files for separating out vfio-specific work for s390
> > pci. Add the first such routine, which issues VFIO_IOMMU_GET_INFO
> > ioctl to collect the current dma available count.
> > 
> > Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
> > Reviewed-by: Cornelia Huck <cohuck@redhat.com>
> > [aw: Fix non-Linux build with CONFIG_LINUX]
> > Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
> > ---
> >  hw/s390x/meson.build             |    1 +
> >  hw/s390x/s390-pci-vfio.c         |   54 ++++++++++++++++++++++++++++++++++++++
> >  include/hw/s390x/s390-pci-vfio.h |   24 +++++++++++++++++
> >  3 files changed, 79 insertions(+)
> >  create mode 100644 hw/s390x/s390-pci-vfio.c
> >  create mode 100644 include/hw/s390x/s390-pci-vfio.h
> > 
> > diff --git a/hw/s390x/meson.build b/hw/s390x/meson.build
> > index 948ceae7a7b3..f4663a835514 100644
> > --- a/hw/s390x/meson.build
> > +++ b/hw/s390x/meson.build
> > @@ -27,6 +27,7 @@ s390x_ss.add(when: 'CONFIG_KVM', if_true: files(
> >  ))
> >  s390x_ss.add(when: 'CONFIG_S390_CCW_VIRTIO', if_true: files('s390-virtio-ccw.c'))
> >  s390x_ss.add(when: 'CONFIG_TERMINAL3270', if_true: files('3270-ccw.c'))
> > +s390x_ss.add(when: 'CONFIG_LINUX', if_true: files('s390-pci-vfio.c'))

I think we need s/CONFIG_LINUX/CONFIG_VFIO/ here.

> >  
> >  virtio_ss = ss.source_set()
> >  virtio_ss.add(files('virtio-ccw.c'))
> > diff --git a/hw/s390x/s390-pci-vfio.c b/hw/s390x/s390-pci-vfio.c
> > new file mode 100644
> > index 000000000000..cb3f4d98adf8
> > --- /dev/null
> > +++ b/hw/s390x/s390-pci-vfio.c
> > @@ -0,0 +1,54 @@
> > +/*
> > + * s390 vfio-pci interfaces
> > + *
> > + * Copyright 2020 IBM Corp.
> > + * Author(s): Matthew Rosato <mjrosato@linux.ibm.com>
> > + *
> > + * This work is licensed under the terms of the GNU GPL, version 2 or (at
> > + * your option) any later version. See the COPYING file in the top-level
> > + * directory.
> > + */
> > +
> > +#include <sys/ioctl.h>
> > +
> > +#include "qemu/osdep.h"
> > +#include "hw/s390x/s390-pci-vfio.h"
> > +#include "hw/vfio/vfio-common.h"
> > +
> > +/*
> > + * Get the current DMA available count from vfio.  Returns true if vfio is
> > + * limiting DMA requests, false otherwise.  The current available count read
> > + * from vfio is returned in avail.
> > + */
> > +bool s390_pci_update_dma_avail(int fd, unsigned int *avail)
> > +{
> > +    g_autofree struct vfio_iommu_type1_info *info;
> > +    uint32_t argsz;
> > +
> > +    assert(avail);
> > +
> > +    argsz = sizeof(struct vfio_iommu_type1_info);
> > +    info = g_malloc0(argsz);
> > +
> > +    /*
> > +     * If the specified argsz is not large enough to contain all capabilities
> > +     * it will be updated upon return from the ioctl.  Retry until we have
> > +     * a big enough buffer to hold the entire capability chain.
> > +     */
> > +retry:
> > +    info->argsz = argsz;
> > +
> > +    if (ioctl(fd, VFIO_IOMMU_GET_INFO, info)) {
> > +        return false;
> > +    }
> > +
> > +    if (info->argsz > argsz) {
> > +        argsz = info->argsz;
> > +        info = g_realloc(info, argsz);
> > +        goto retry;
> > +    }
> > +
> > +    /* If the capability exists, update with the current value */
> > +    return vfio_get_info_dma_avail(info, avail);
> > +}  
> 
> --without-default-devices configuration is broken, bisected
> to this commit:

Hm. Is this run in any of the CI tests? I did not even realize it
existed :)

> 
> hw/s390x/s390-pci-vfio.c:52: undefined reference to
> `vfio_get_info_dma_avail'
> 
> Can you have a look please?
> 
> Thanks.
>