Max Makarov aef0a43b52 vdpa: fix RX failure after device reset by always using base 0 ...

After a vDPA device reset, activate_vdpa() read avail_idx from guest
memory to pass as the vring base via VHOST_SET_VRING_BASE. However,
the guest memory still contained the stale avail_idx from the previous
session. For a 256-entry ring, this meant base=256, causing the
hardware to believe the entire RX ring was consumed with no available
buffers — RX silently stopped while TX continued to work.

QEMU handles this correctly by tracking last_avail_idx internally
(reset to 0 in virtio_reset()) and passing that value, rather than
reading from guest memory.

Fix by always passing base=0 to set_vring_base(). After a device
reset, both the guest driver and the vhost backend restart their rings
from index 0. For live migration, the correct base should come from
VHOST_GET_VRING_BASE (saved before the migration), not guest memory.

Tested with mlx5_vdpa (ConnectX-6 Dx) + Windows Server 2025 (netkvm).
Before: RX=0 after 3rd driver activation. After: full connectivity.

Signed-off-by: Max Makarov <maxpain@linux.com>

2026-04-07 00:48:19 +00:00

..

src

vdpa: fix RX failure after device reset by always using base 0

2026-04-07 00:48:19 +00:00

build.rs

build: Add "fuzzing" as a valid cfg(..) attribute

2024-05-08 08:10:28 +00:00

Cargo.toml

virtio-devices: Add set_notifier() method to VirtioInterrupt

2026-03-18 09:25:27 +00:00