Re: [RFC v3 12/25] vfio/common: add pasid_alloc/free support

[Peter Xu <peterx@redhat.com>]

On Wed, Jan 29, 2020 at 04:16:43AM -0800, Liu, Yi L wrote:
> From: Liu Yi L <yi.l.liu@intel.com>
> 
> This patch adds VFIO pasid alloc/free support to allow host intercept
> in PASID allocation for VM by adding VFIO implementation of
> DualStageIOMMUOps.pasid_alloc/free callbacks.
> 
> Cc: Kevin Tian <kevin.tian@intel.com>
> Cc: Jacob Pan <jacob.jun.pan@linux.intel.com>
> Cc: Peter Xu <peterx@redhat.com>
> Cc: Eric Auger <eric.auger@redhat.com>
> Cc: Yi Sun <yi.y.sun@linux.intel.com>
> Cc: David Gibson <david@gibson.dropbear.id.au>
> Cc: Alex Williamson <alex.williamson@redhat.com>
> Signed-off-by: Liu Yi L <yi.l.liu@intel.com>
> ---
>  hw/vfio/common.c | 42 ++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 42 insertions(+)
> 
> diff --git a/hw/vfio/common.c b/hw/vfio/common.c
> index a07824b..014f4e7 100644
> --- a/hw/vfio/common.c
> +++ b/hw/vfio/common.c
> @@ -1179,7 +1179,49 @@ static int vfio_get_iommu_type(VFIOContainer *container,
>      return -EINVAL;
>  }
>  
> +static int vfio_ds_iommu_pasid_alloc(DualStageIOMMUObject *dsi_obj,
> +                         uint32_t min, uint32_t max, uint32_t *pasid)
> +{
> +    VFIOContainer *container = container_of(dsi_obj, VFIOContainer, dsi_obj);
> +    struct vfio_iommu_type1_pasid_request req;
> +    unsigned long argsz;
> +
> +    argsz = sizeof(req);
> +    req.argsz = argsz;
> +    req.flags = VFIO_IOMMU_PASID_ALLOC;
> +    req.alloc_pasid.min = min;
> +    req.alloc_pasid.max = max;
> +
> +    if (ioctl(container->fd, VFIO_IOMMU_PASID_REQUEST, &req)) {
> +        error_report("%s: %d, alloc failed", __func__, -errno);
> +        return -errno;

Note that errno is prone to change by other syscalls.  Better cache it
right after the ioctl.

> +    }
> +    *pasid = req.alloc_pasid.result;
> +    return 0;
> +}
> +
> +static int vfio_ds_iommu_pasid_free(DualStageIOMMUObject *dsi_obj,
> +                                     uint32_t pasid)
> +{
> +    VFIOContainer *container = container_of(dsi_obj, VFIOContainer, dsi_obj);
> +    struct vfio_iommu_type1_pasid_request req;
> +    unsigned long argsz;
> +
> +    argsz = sizeof(req);
> +    req.argsz = argsz;
> +    req.flags = VFIO_IOMMU_PASID_FREE;
> +    req.free_pasid = pasid;
> +
> +    if (ioctl(container->fd, VFIO_IOMMU_PASID_REQUEST, &req)) {
> +        error_report("%s: %d, free failed", __func__, -errno);
> +        return -errno;

Same here.

> +    }
> +    return 0;
> +}
> +
>  static struct DualStageIOMMUOps vfio_ds_iommu_ops = {
> +    .pasid_alloc = vfio_ds_iommu_pasid_alloc,
> +    .pasid_free = vfio_ds_iommu_pasid_free,
>  };
>  
>  static int vfio_get_iommu_info(VFIOContainer *container,
> -- 
> 2.7.4
> 

-- 
Peter Xu