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

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

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'))
>  
>  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:

hw/s390x/s390-pci-vfio.c:52: undefined reference to
`vfio_get_info_dma_avail'

Can you have a look please?

Thanks.