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authorEugenio Pérez <eperezma@redhat.com>2023-03-02 19:18:57 +0100
committerMichael S. Tsirkin <mst@redhat.com>2023-03-13 02:29:12 -0400
commitb4cca6d48eb3fa6f0d9caba4329b1a2b0ff67a77 (patch)
treef1210b41149ec5866b469ade97c8dcd19449e507 /drivers/vdpa
parent5a522150093a0eabae9470a70a37a6e436bfad08 (diff)
vdpa_sim: set last_used_idx as last_avail_idx in vdpasim_queue_ready
Starting from an used_idx different than 0 is needed in use cases like virtual machine migration. Not doing so and letting the caller set an avail idx different than 0 causes destination device to try to use old buffers that source driver already recover and are not available anymore. Since vdpa_sim does not support receive inflight descriptors as a destination of a migration, let's set both avail_idx and used_idx the same at vq start. This is how vhost-user works in a VHOST_SET_VRING_BASE call. Although the simple fix is to set last_used_idx at vdpasim_set_vq_state, it would be reset at vdpasim_queue_ready. The last_avail_idx case is fixed with commit 0e84f918fac8 ("vdpa_sim: not reset state in vdpasim_queue_ready"). Since the only option is to make it equal to last_avail_idx, adding the only change needed here. This was discovered and tested live migrating the vdpa_sim_net device. Fixes: 2c53d0f64c06 ("vdpasim: vDPA device simulator") Reviewed-by: Stefano Garzarella <sgarzare@redhat.com> Signed-off-by: Eugenio Pérez <eperezma@redhat.com> Message-Id: <20230302181857.925374-1-eperezma@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Diffstat (limited to 'drivers/vdpa')
-rw-r--r--drivers/vdpa/vdpa_sim/vdpa_sim.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
index 6a0a65814626..eea23c630f7c 100644
--- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c
@@ -68,6 +68,17 @@ static void vdpasim_queue_ready(struct vdpasim *vdpasim, unsigned int idx)
(uintptr_t)vq->device_addr);
vq->vring.last_avail_idx = last_avail_idx;
+
+ /*
+ * Since vdpa_sim does not support receive inflight descriptors as a
+ * destination of a migration, let's set both avail_idx and used_idx
+ * the same at vq start. This is how vhost-user works in a
+ * VHOST_SET_VRING_BASE call.
+ *
+ * Although the simple fix is to set last_used_idx at
+ * vdpasim_set_vq_state, it would be reset at vdpasim_queue_ready.
+ */
+ vq->vring.last_used_idx = last_avail_idx;
vq->vring.notify = vdpasim_vq_notify;
}