[PATCH V1 6/6] arm/xen: Assign xen-grant DMA ops for xen-grant DMA devices

[Oleksandr Tyshchenko <olekstysh@xxxxxxxxx>]

From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>

As the main (and single at the moment) purpose of xen-grant
DMA devices is to enable using virtio devices in Xen guests
in a safe manner, assign xen-grant DMA ops only if restricted
access to the guest memory is enabled.

Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>
---
Changes RFC -> V1:
   - update commit subject/description
   - remove #ifdef CONFIG_XEN_VIRTIO
   - re-organize the check taking into the account that
     swiotlb and virtio cases are mutually exclusive
   - update according to the new naming scheme:
     s/virtio/grant_dma
---
 include/xen/arm/xen-ops.h | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/include/xen/arm/xen-ops.h b/include/xen/arm/xen-ops.h
index 288deb1..26954e5 100644
--- a/include/xen/arm/xen-ops.h
+++ b/include/xen/arm/xen-ops.h
@@ -2,12 +2,17 @@
 #ifndef _ASM_ARM_XEN_OPS_H
 #define _ASM_ARM_XEN_OPS_H
 
+#include <linux/virtio_config.h>
 #include <xen/swiotlb-xen.h>
+#include <xen/xen-ops.h>
 
 static inline void xen_setup_dma_ops(struct device *dev)
 {
 #ifdef CONFIG_XEN
-       if (xen_swiotlb_detect())
+       if (arch_has_restricted_virtio_memory_access() &&
+                       xen_is_grant_dma_device(dev))
+               xen_grant_setup_dma_ops(dev);
+       else if (xen_swiotlb_detect())
                dev->dma_ops = &xen_swiotlb_dma_ops;
 #endif
 }
-- 
2.7.4