xen/virtio: Optimize the setup of "xen-grant-dma" devices

This is needed to avoid having to parse the same device-tree
several times for a given device.

For this to work we need to install the xen_virtio_restricted_mem_acc
callback in Arm's xen_guest_init() which is same callback as x86's
PV and HVM modes already use and remove the manual assignment in
xen_setup_dma_ops(). Also we need to split the code to initialize
backend_domid into a separate function.

Prior to current patch we parsed the device-tree three times:
1. xen_setup_dma_ops()->...->xen_is_dt_grant_dma_device()
2. xen_setup_dma_ops()->...->xen_dt_grant_init_backend_domid()
3. xen_virtio_mem_acc()->...->xen_is_dt_grant_dma_device()

With current patch we parse the device-tree only once in
xen_virtio_restricted_mem_acc()->...->xen_dt_grant_init_backend_domid()

Other benefits are:
- Not diverge from x86 when setting up Xen grant DMA ops
- Drop several global functions

Signed-off-by: Oleksandr Tyshchenko <[email protected]>
Reviewed-by: Xenia Ragiadakou <[email protected]>
Reviewed-by: Stefano Stabellini <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Juergen Gross <[email protected]>

0 files changed, 0 insertions, 0 deletions