Re: [PATCH v3 4/5] s390x/pci: Add routine to get the vfio dma available count

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

On 9/15/20 9:14 PM, Matthew Rosato wrote:
> 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>
> ---
>  hw/s390x/meson.build     |  1 +
>  hw/s390x/s390-pci-vfio.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++
>  hw/s390x/s390-pci-vfio.h | 17 +++++++++++++++
>  3 files changed, 72 insertions(+)
>  create mode 100644 hw/s390x/s390-pci-vfio.c
>  create mode 100644 hw/s390x/s390-pci-vfio.h
> 
> diff --git a/hw/s390x/meson.build b/hw/s390x/meson.build
> index b63782d..ed2f66b 100644
> --- a/hw/s390x/meson.build
> +++ b/hw/s390x/meson.build
> @@ -10,6 +10,7 @@ s390x_ss.add(files(
>    's390-ccw.c',
>    's390-pci-bus.c',
>    's390-pci-inst.c',
> +  's390-pci-vfio.c',
>    's390-skeys.c',
>    's390-stattrib.c',
>    's390-virtio-hcall.c',
> diff --git a/hw/s390x/s390-pci-vfio.c b/hw/s390x/s390-pci-vfio.c
> new file mode 100644
> index 0000000..75e3ac1
> --- /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 "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;
> +    int ret;
> +
> +    assert(avail);
> +
> +    argsz = sizeof(struct vfio_iommu_type1_info);
> +    info = g_malloc0(argsz);
> +    info->argsz = argsz;
> +    /*
> +     * If the specified argsz is not large enough to contain all
> +     * capabilities it will be updated upon return.  In this case
> +     * use the updated value to get the entire capability chain.
> +     */
> +    ret = ioctl(fd, VFIO_IOMMU_GET_INFO, info);
> +    if (argsz != info->argsz) {
> +        argsz = info->argsz;
> +        info = g_realloc(info, argsz);

Do we need to bzero [sizeof(struct vfio_iommu_type1_info)..argsz[?

> +        info->argsz = argsz;
> +        ret = ioctl(fd, VFIO_IOMMU_GET_INFO, info);
> +    }
> +
> +    if (ret) {
> +        return false;
> +    }
> +
> +    /* If the capability exists, update with the current value */
> +    return vfio_get_info_dma_avail(info, avail);
> +}
> +
> diff --git a/hw/s390x/s390-pci-vfio.h b/hw/s390x/s390-pci-vfio.h
> new file mode 100644
> index 0000000..2a5a261
> --- /dev/null
> +++ b/hw/s390x/s390-pci-vfio.h
> @@ -0,0 +1,17 @@
> +/*
> + * 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.
> + */
> +
> +#ifndef HW_S390_PCI_VFIO_H
> +#define HW_S390_PCI_VFIO_H
> +
> +bool s390_pci_update_dma_avail(int fd, unsigned int *avail);
> +
> +#endif
>