Qemu and virtio 1.0

Rusty Russell
2015-02-25T04:20:22Z

OK, I am trying to experiment with virtio 1.0 support using the
latest kernel and MST's qemu tree:

https://git.kernel.org/cgit/virt/kvm/mst/qemu.git/?h=virtio-1.0

The first issue is that the device config endian was wrong (see
attached patch).

I'm now setting up a BE guest on my x86 laptop, and a BE and LE guest
on a BE powerpc machine, to check that all combinations work correctly.
If others test too, that would be appreciated!

Cheers,
Rusty.

>From 95ac91554ed602f856a2a5fcc25eaffcad1b1c8d Mon Sep 17 00:00:00 2001
From: Rusty Russell <rusty@rustcorp.com.au>
Date: Tue, 24 Feb 2015 14:47:44 +1030
Subject: [PATCH] virtio_config_write*/virtio_config_read*: Don't endian swap
for virtio 1.0.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index 079944c..882a31b 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -662,7 +662,12 @@ uint32_t virtio_config_readw(VirtIODevice *vdev, uint32_t addr)

k->get_config(vdev, vdev->config);

- val = lduw_p(vdev->config + addr);
+ /* Virtio 1.0 is always LE */
+ if (virtio_has_feature(vdev, VIRTIO_F_VERSION_1)) {
+ val = lduw_le_p(vdev->config + addr);
+ } else {
+ val = lduw_p(vdev->config + addr);
+ }
return val;
}

@@ -677,7 +682,12 @@ uint32_t virtio_config_readl(VirtIODevice *vdev, uint32_t addr)

k->get_config(vdev, vdev->config);

- val = ldl_p(vdev->config + addr);
+ /* Virtio 1.0 is always LE */
+ if (virtio_has_feature(vdev, VIRTIO_F_VERSION_1)) {
+ val = ldl_le_p(vdev->config + addr);
+ } else {
+ val = ldl_p(vdev->config + addr);
+ }
return val;
}

@@ -706,7 +716,12 @@ void virtio_config_writew(VirtIODevice *vdev, uint32_t addr, uint32_t data)
return;
}

- stw_p(vdev->config + addr, val);
+ /* Virtio 1.0 is always LE */
+ if (virtio_has_feature(vdev, VIRTIO_F_VERSION_1)) {
+ stw_le_p(vdev->config + addr, val);
+ } else {
+ stw_p(vdev->config + addr, val);
+ }

if (k->set_config) {
k->set_config(vdev, vdev->config);
@@ -722,7 +737,12 @@ void virtio_config_writel(VirtIODevice *vdev, uint32_t addr, uint32_t data)
return;
}

- stl_p(vdev->config + addr, val);
+ /* Virtio 1.0 is always LE */
+ if (virtio_has_feature(vdev, VIRTIO_F_VERSION_1)) {
+ stl_le_p(vdev->config + addr, val);
+ } else {
+ stl_p(vdev->config + addr, val);
+ }

if (k->set_config) {
k->set_config(vdev, vdev->config);