From: Abhimanyu Saini <absa...@amd.com>
libvhost calls dev_conf() before prosessing the
VHOST_USER_SET_VRING_CALL message for the last VQ. So
this message is processed after dev_conf() returns.
However, the dev_conf() function spawns a thread to set
rte_vhost_host_notifier_ctrl() before returning control to
libvhost. This parallel thread in turn invokes get_notify_area().
To get the notify_area, the vdpa driver needs to query the HW and
for this query it needs an enabled VQ.
But at the same time libvhost is processing the last
VHOST_USER_SET_VRING_CALL, and to do that it disables the last VQ.
Hence there is a race b/w the libvhost and the vdpa driver.
To resolve this race condition, query the HW and cache notify_area
inside dev_conf() instead of doing it the parallel thread.
Signed-off-by: Abhimanyu Saini <absa...@amd.com>
---
drivers/vdpa/sfc/sfc_vdpa_ops.c | 36 ++++++++++++++++++------------------
drivers/vdpa/sfc/sfc_vdpa_ops.h | 1 +
2 files changed, 19 insertions(+), 18 deletions(-)
diff --git a/drivers/vdpa/sfc/sfc_vdpa_ops.c b/drivers/vdpa/sfc/sfc_vdpa_ops.c
index 63aa52d..b84699d 100644
--- a/drivers/vdpa/sfc/sfc_vdpa_ops.c
+++ b/drivers/vdpa/sfc/sfc_vdpa_ops.c
@@ -222,6 +222,7 @@
sfc_vdpa_virtq_start(struct sfc_vdpa_ops_data *ops_data, int vq_num)
{
int rc;
+ uint32_t doorbell;
efx_virtio_vq_t *vq;
struct sfc_vdpa_vring_info vring;
efx_virtio_vq_cfg_t vq_cfg;
@@ -270,22 +271,35 @@
/* Start virtqueue */
rc = efx_virtio_qstart(vq, &vq_cfg, &vq_dyncfg);
if (rc != 0) {
- /* destroy virtqueue */
sfc_vdpa_err(ops_data->dev_handle,
"virtqueue start failed: %s",
rte_strerror(rc));
- efx_virtio_qdestroy(vq);
goto fail_virtio_qstart;
}
sfc_vdpa_info(ops_data->dev_handle,
"virtqueue started successfully for vq_num %d", vq_num);
+ rc = efx_virtio_get_doorbell_offset(vq, &doorbell);
+ if (rc != 0) {
+ sfc_vdpa_err(ops_data->dev_handle,
+ "failed to get doorbell offset: %s",
+ rte_strerror(rc));
+ goto fail_doorbell;
+ }
+
+ /*
+ * Cache the bar_offset here for each VQ here, it will come
+ * in handy when sfc_vdpa_get_notify_area() is invoked.
+ */
+ ops_data->vq_cxt[vq_num].doorbell = (void *)(uintptr_t)doorbell;
ops_data->vq_cxt[vq_num].enable = B_TRUE;
return rc;
+fail_doorbell:
fail_virtio_qstart:
+ efx_virtio_qdestroy(vq);
fail_vring_info:
return rc;
}
@@ -792,8 +806,6 @@
int ret;
efx_nic_t *nic;
int vfio_dev_fd;
- efx_rc_t rc;
- unsigned int bar_offset;
volatile void *doorbell;
struct rte_pci_device *pci_dev;
struct rte_vdpa_device *vdpa_dev;
@@ -824,19 +836,6 @@
return -1;
}
- if (ops_data->vq_cxt[qid].enable != B_TRUE) {
- sfc_vdpa_err(dev, "vq is not enabled");
- return -1;
- }
-
- rc = efx_virtio_get_doorbell_offset(ops_data->vq_cxt[qid].vq,
- &bar_offset);
- if (rc != 0) {
- sfc_vdpa_err(dev, "failed to get doorbell offset: %s",
- rte_strerror(rc));
- return rc;
- }
-
reg.index = sfc_vdpa_adapter_by_dev_handle(dev)->mem_bar.esb_rid;
ret = ioctl(vfio_dev_fd, VFIO_DEVICE_GET_REGION_INFO, ®);
if (ret != 0) {
@@ -845,7 +844,8 @@
return ret;
}
- *offset = reg.offset + bar_offset;
+ /* Use bar_offset that was cached during sfc_vdpa_virtq_start() */
+ *offset = reg.offset + (uint64_t)ops_data->vq_cxt[qid].doorbell;
len = (1U << encp->enc_vi_window_shift) / 2;
if (len >= sysconf(_SC_PAGESIZE)) {
diff --git a/drivers/vdpa/sfc/sfc_vdpa_ops.h b/drivers/vdpa/sfc/sfc_vdpa_ops.h
index 6d790fd..9dbd5b8 100644
--- a/drivers/vdpa/sfc/sfc_vdpa_ops.h
+++ b/drivers/vdpa/sfc/sfc_vdpa_ops.h
@@ -35,6 +35,7 @@ struct sfc_vdpa_vring_info {
};
typedef struct sfc_vdpa_vq_context_s {
+ volatile void *doorbell;
uint8_t enable;
uint32_t pidx;
uint32_t cidx;
--
1.8.3.1
