Re: [Qemu-devel] [RFC PATCH 1/7] virtio: Add shared memory capability

[Eric Blake <eblake@redhat.com>]

On 12/10/18 11:31 AM, Dr. David Alan Gilbert (git) wrote:
> From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
> 
> Define a new capability type 'VIRTIO_PCI_CAP_SHARED_MEMORY_CFG'
> and the data structure 'virtio_pci_shm_cap' to go with it.
> They allow defining shared memory regions with sizes and offsets
> of 2^32 and more.
> Multiple instances of the capability are allowed and distinguished
> by a device-specific 'id'.
> 
> Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> ---
>   hw/virtio/virtio-pci.c                      | 20 ++++++++++++++++++++
>   include/standard-headers/linux/virtio_pci.h |  9 +++++++++
>   2 files changed, 29 insertions(+)
> 

> +++ b/include/standard-headers/linux/virtio_pci.h
> @@ -113,6 +113,8 @@
>   #define VIRTIO_PCI_CAP_DEVICE_CFG	4
>   /* PCI configuration access */
>   #define VIRTIO_PCI_CAP_PCI_CFG		5
> +/* Additional shared memory capability */
> +#define VIRTIO_PCI_CAP_SHARED_MEMORY_CFG 8
>   
>   /* This is the PCI capability header: */
>   struct virtio_pci_cap {
> @@ -163,6 +165,13 @@ struct virtio_pci_cfg_cap {
>   	uint8_t pci_cfg_data[4]; /* Data for BAR access. */
>   };
>   
> +struct virtio_pci_shm_cap {
> +	struct virtio_pci_cap cap;
> +	uint32_t offset_hi;             /* Most sig 32 bits of offset */
> +	uint32_t length_hi;             /* Most sig 32 bits of length */
> +        uint8_t  id;                    /* To distinguish shm chunks */

TAB damage.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org