Re: [Qemu-devel] [PATCH v14 13/22] vfio: Introduce common function to add capabilities

[Auger Eric <eric.auger@redhat.com>]

Hi,

On 16/11/2016 21:46, Kirti Wankhede wrote:
> Vendor driver using mediated device framework should use
> vfio_info_add_capability() to add capabilities.
> Introduced this function to reduce code duplication in vendor drivers.
> 
> vfio_info_cap_shift() manipulated a data buffer to add an offset to each
> element in a chain. This data buffer is documented in a uapi header.
> Changing vfio_info_cap_shift symbol to be available to all drivers.
> 
> Signed-off-by: Kirti Wankhede <kwankhede@nvidia.com>
> Signed-off-by: Neo Jia <cjia@nvidia.com>
> Change-Id: I6fca329fa2291f37a2c859d0bc97574d9e2ce1a6
> ---
>  drivers/vfio/vfio.c  | 60 +++++++++++++++++++++++++++++++++++++++++++++++++++-
>  include/linux/vfio.h |  3 +++
>  2 files changed, 62 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/vfio/vfio.c b/drivers/vfio/vfio.c
> index c850ba324be2..82257cf30f52 100644
> --- a/drivers/vfio/vfio.c
> +++ b/drivers/vfio/vfio.c
> @@ -1797,8 +1797,66 @@ void vfio_info_cap_shift(struct vfio_info_cap *caps, size_t offset)
>  	for (tmp = caps->buf; tmp->next; tmp = (void *)tmp + tmp->next - offset)
>  		tmp->next += offset;
>  }
> -EXPORT_SYMBOL_GPL(vfio_info_cap_shift);
> +EXPORT_SYMBOL(vfio_info_cap_shift);
>  
> +static int sparse_mmap_cap(struct vfio_info_cap *caps, void *cap_type)
> +{
> +	struct vfio_info_cap_header *header;
> +	struct vfio_region_info_cap_sparse_mmap *sparse_cap, *sparse = cap_type;
> +	size_t size;
> +
> +	size = sizeof(*sparse) + sparse->nr_areas *  sizeof(*sparse->areas);
> +	header = vfio_info_cap_add(caps, size,
> +				   VFIO_REGION_INFO_CAP_SPARSE_MMAP, 1);
> +	if (IS_ERR(header))
> +		return PTR_ERR(header);
> +
> +	sparse_cap = container_of(header,
> +			struct vfio_region_info_cap_sparse_mmap, header);
> +	sparse_cap->nr_areas = sparse->nr_areas;
> +	memcpy(sparse_cap->areas, sparse->areas,
> +	       sparse->nr_areas * sizeof(*sparse->areas));
> +	return 0;
> +}
> +
> +static int region_type_cap(struct vfio_info_cap *caps, void *cap_type)
> +{
> +	struct vfio_info_cap_header *header;
> +	struct vfio_region_info_cap_type *type_cap, *cap = cap_type;
> +
> +	header = vfio_info_cap_add(caps, sizeof(*cap),
> +				   VFIO_REGION_INFO_CAP_TYPE, 1);
> +	if (IS_ERR(header))
> +		return PTR_ERR(header);
> +
> +	type_cap = container_of(header, struct vfio_region_info_cap_type,
> +				header);
> +	type_cap->type = cap->type;
> +	type_cap->subtype = cap->subtype;
> +	return 0;
> +}
> +
> +int vfio_info_add_capability(struct vfio_info_cap *caps, int cap_type_id,
> +			     void *cap_type)
> +{
> +	int ret = -EINVAL;
> +
> +	if (!cap_type)
> +		return 0;
> +
> +	switch (cap_type_id) {
> +	case VFIO_REGION_INFO_CAP_SPARSE_MMAP:
> +		ret = sparse_mmap_cap(caps, cap_type);
> +		break;
> +
> +	case VFIO_REGION_INFO_CAP_TYPE:
> +		ret = region_type_cap(caps, cap_type);
> +		break;
> +	}
> +
> +	return ret;
> +}
> +EXPORT_SYMBOL(vfio_info_add_capability);
>  
>  /*
>   * Pin a set of guest PFNs and return their associated host PFNs for local
> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
> index 6ab13f7e2920..e26f7ccab564 100644
> --- a/include/linux/vfio.h
> +++ b/include/linux/vfio.h
> @@ -126,6 +126,9 @@ extern struct vfio_info_cap_header *vfio_info_cap_add(
>  		struct vfio_info_cap *caps, size_t size, u16 id, u16 version);
>  extern void vfio_info_cap_shift(struct vfio_info_cap *caps, size_t offset);
>  
> +extern int vfio_info_add_capability(struct vfio_info_cap *caps,
> +				    int cap_type_id, void *cap_type);
> +
>  struct pci_dev;
>  #ifdef CONFIG_EEH
>  extern void vfio_spapr_pci_eeh_open(struct pci_dev *pdev);
> 
Reviewed-by: Eric Auger <eric.auger@redhat.com>

Eric