Re: [PATCH RFC v1 10/11] uapi/virtio-iommu: Add a new request type to send page response

[Jean-Philippe Brucker]

On Fri, Apr 23, 2021 at 03:21:46PM +0530, Vivek Gautam wrote:
> Once the page faults are handled, the response has to be sent to
> virtio-iommu backend, from where it can be sent to the host to
> prepare the response to a generated io page fault by the device.
> Add a new virt-queue request type to handle this.
> 
> Signed-off-by: Vivek Gautam <vivek.gautam@xxxxxxx>
> ---
>  include/uapi/linux/virtio_iommu.h | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/include/uapi/linux/virtio_iommu.h b/include/uapi/linux/virtio_iommu.h
> index c12d9b6a7243..1b174b98663a 100644
> --- a/include/uapi/linux/virtio_iommu.h
> +++ b/include/uapi/linux/virtio_iommu.h
> @@ -48,6 +48,7 @@ struct virtio_iommu_config {
>  #define VIRTIO_IOMMU_T_PROBE			0x05
>  #define VIRTIO_IOMMU_T_ATTACH_TABLE		0x06
>  #define VIRTIO_IOMMU_T_INVALIDATE		0x07
> +#define VIRTIO_IOMMU_T_PAGE_RESP		0x08
>  
>  /* Status types */
>  #define VIRTIO_IOMMU_S_OK			0x00
> @@ -70,6 +71,23 @@ struct virtio_iommu_req_tail {
>  	__u8					reserved[3];
>  };
>  
> +struct virtio_iommu_req_page_resp {
> +	struct virtio_iommu_req_head		head;
> +	__le32					domain;

I don't think we need this field, since the fault report doesn't come with
a domain.

> +	__le32					endpoint;
> +#define VIRTIO_IOMMU_PAGE_RESP_PASID_VALID	(1 << 0)

To be consistent with the rest of the document this would be
VIRTIO_IOMMU_PAGE_RESP_F_PASID_VALID

> +	__le32					flags;
> +	__le32					pasid;
> +	__le32					grpid;
> +#define VIRTIO_IOMMU_PAGE_RESP_SUCCESS		(0x0)
> +#define VIRTIO_IOMMU_PAGE_RESP_INVALID		(0x1)
> +#define VIRTIO_IOMMU_PAGE_RESP_FAILURE		(0x2)
> +	__le16					resp_code;
> +	__u8					pasid_valid;

This field isn't needed since there already is
VIRTIO_IOMMU_PAGE_RESP_PASID_VALID

> +	__u8					reserved[9];
> +	struct virtio_iommu_req_tail		tail;
> +};

I'd align the size of the struct to 16 bytes, but I don't think that's
strictly necessary.

Thanks,
Jean

> +
>  struct virtio_iommu_req_attach {
>  	struct virtio_iommu_req_head		head;
>  	__le32					domain;
> -- 
> 2.17.1
>