Re: [PATCH v2 1/3] vfio: Find DMA available capability

[Cornelia Huck]

On Mon, 14 Sep 2020 18:29:28 -0400
Matthew Rosato <mjrosato@linux.ibm.com> wrote:

> The underlying host may be limiting the number of outstanding DMA
> requests for type 1 IOMMU.  Add helper functions to check for the
> DMA available capability and retrieve the current number of DMA
> mappings allowed.
> 
> Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
> ---
>  hw/vfio/common.c              | 37 +++++++++++++++++++++++++++++++++++++
>  include/hw/vfio/vfio-common.h |  2 ++
>  2 files changed, 39 insertions(+)
> 

(...)

> +bool vfio_get_info_dma_avail(struct vfio_iommu_type1_info *info,
> +                             unsigned int *avail)
> +{
> +    struct vfio_info_cap_header *hdr;
> +    struct vfio_iommu_type1_info_dma_avail *cap;
> +
> +    /* If the capability cannot be found, assume no DMA limiting */
> +    hdr = vfio_get_iommu_type1_info_cap(info,
> +                                        VFIO_IOMMU_TYPE1_INFO_DMA_AVAIL);

...don't you need a headers sync first to get the new definitions?

(...)