On Mon, Nov 14, 2022 at 10:36:52AM +0100, Gerd Hoffmann wrote:
On Mon, Nov 14, 2022 at 11:58:17AM +0800, Xuan Zhuo wrote:
Under mmio, when we read the feature from the device, we should read the high 32-bit part. Similarly, when writing the feature back, we should also write back the high 32-bit feature.
Signed-off-by: Xuan Zhuo xuanzhuo@linux.alibaba.com
src/hw/virtio-pci.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/src/hw/virtio-pci.c b/src/hw/virtio-pci.c index 213c497..89a4f50 100644 --- a/src/hw/virtio-pci.c +++ b/src/hw/virtio-pci.c @@ -193,7 +193,8 @@ u64 vp_get_features(struct vp_device *vp) if (vp->use_mmio) { vp_write(&vp->common, virtio_mmio_cfg, device_feature_select, 0); f0 = vp_read(&vp->common, virtio_mmio_cfg, device_feature);
f1 = 0;
vp_write(&vp->common, virtio_mmio_cfg, device_feature_select, 1);f1 = vp_read(&vp->common, virtio_mmio_cfg, device_feature);You need to check the version here, legacy virtio has only 32 feature bits so you can't read/write f1 like this.
if (vp_read(&vp->common, virtio_mmio_cfg, version) == 2) { /* virtio 1.0 */ } else { /* legacy */ }(see also vp_find_vq()).
take care, Gerd
Hmm we won't want to re-read it many times I think. It probably makes sense to add a new field u8 mmio_version, and set it in vp_init_simple.