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[Qemu-devel] [PATCH] dataplane: drop copy_in_vring_desc()
From: |
Greg Kurz |
Subject: |
[Qemu-devel] [PATCH] dataplane: drop copy_in_vring_desc() |
Date: |
Thu, 25 Jun 2015 17:26:09 +0200 |
User-agent: |
StGit/0.17.1-dirty |
During early virtio 1.0 devel, there were several proposals about how to
deal endianness of the vring descriptor fields:
- convert the decriptor to host endianness in a single place, and use its
fields directly in the code
- keep the descriptor untouched and use virtio memory helpers to access its
fields with the appropriate endianness
It seems like both approaches got merged: commit f5a5628cf0b6 introduces
an extra swap that negates the one brought by commit b0e5d90ebc3e. This
breaks cross-endian setups with the following error:
Failed to map descriptor addr 0x18e2517e00000000 len 268435456
A solution could be to revert f5a5628cf0b6, but dropping copy_in_vring_desc()
is equivalent and gives a smaller patch.
Signed-off-by: Greg Kurz <address@hidden>
---
hw/virtio/dataplane/vring.c | 14 ++------------
1 file changed, 2 insertions(+), 12 deletions(-)
diff --git a/hw/virtio/dataplane/vring.c b/hw/virtio/dataplane/vring.c
index 35891856ee06..3fa421b9d773 100644
--- a/hw/virtio/dataplane/vring.c
+++ b/hw/virtio/dataplane/vring.c
@@ -207,16 +207,6 @@ static int get_desc(VirtIODevice *vdev, Vring *vring,
VirtQueueElement *elem,
return 0;
}
-static void copy_in_vring_desc(VirtIODevice *vdev,
- const struct vring_desc *guest,
- struct vring_desc *host)
-{
- host->addr = virtio_ldq_p(vdev, &guest->addr);
- host->len = virtio_ldl_p(vdev, &guest->len);
- host->flags = virtio_lduw_p(vdev, &guest->flags);
- host->next = virtio_lduw_p(vdev, &guest->next);
-}
-
/* This is stolen from linux/drivers/vhost/vhost.c. */
static int get_indirect(VirtIODevice *vdev, Vring *vring,
VirtQueueElement *elem, struct vring_desc *indirect)
@@ -261,7 +251,7 @@ static int get_indirect(VirtIODevice *vdev, Vring *vring,
vring->broken = true;
return -EFAULT;
}
- copy_in_vring_desc(vdev, desc_ptr, &desc);
+ desc = *desc_ptr;
memory_region_unref(mr);
/* Ensure descriptor has been loaded before accessing fields */
@@ -383,7 +373,7 @@ int vring_pop(VirtIODevice *vdev, Vring *vring,
ret = -EFAULT;
goto out;
}
- copy_in_vring_desc(vdev, &vring->vr.desc[i], &desc);
+ desc = vring->vr.desc[i];
/* Ensure descriptor is loaded before accessing fields */
barrier();
- [Qemu-devel] [PATCH] dataplane: drop copy_in_vring_desc(),
Greg Kurz <=