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| author | Andy Lutomirski <luto@kernel.org> | 2016-02-02 21:46:40 -0800 |
|---|---|---|
| committer | Michael S. Tsirkin <mst@redhat.com> | 2016-03-02 17:01:59 +0200 |
| commit | 78fe39872378b0bef00a91181f1947acb8a08500 (patch) | |
| tree | 9d6e181e2614abce3f465cfd04745ea9b1e2744f /drivers/virtio/virtio_ring.c | |
| parent | 7a5589b240b405d55b2b395554082ec284f414bb (diff) | |
| download | lwn-78fe39872378b0bef00a91181f1947acb8a08500.tar.gz lwn-78fe39872378b0bef00a91181f1947acb8a08500.zip | |
vring: Use the DMA API on Xen
Signed-off-by: Andy Lutomirski <luto@kernel.org>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: David Vrabel <david.vrabel@citrix.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>
Diffstat (limited to 'drivers/virtio/virtio_ring.c')
| -rw-r--r-- | drivers/virtio/virtio_ring.c | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c index e46d08107a50..5c802d47892c 100644 --- a/drivers/virtio/virtio_ring.c +++ b/drivers/virtio/virtio_ring.c @@ -25,6 +25,7 @@ #include <linux/hrtimer.h> #include <linux/kmemleak.h> #include <linux/dma-mapping.h> +#include <xen/xen.h> #ifdef DEBUG /* For development, we want to crash whenever the ring is screwed. */ @@ -136,6 +137,17 @@ struct vring_virtqueue { static bool vring_use_dma_api(struct virtio_device *vdev) { + /* + * In theory, it's possible to have a buggy QEMU-supposed + * emulated Q35 IOMMU and Xen enabled at the same time. On + * such a configuration, virtio has never worked and will + * not work without an even larger kludge. Instead, enable + * the DMA API if we're a Xen guest, which at least allows + * all of the sensible Xen configurations to work correctly. + */ + if (xen_domain()) + return true; + return false; } |