-----Original Message-----
From: Maheshwari, Abhishek <[email protected]>
Sent: Thursday, November 3, 2022 3:05 PM
To: [email protected]; Wang, Xiao W <[email protected]>
Cc: [email protected]; [email protected]; Xia, Chenbo <[email protected]>; Mandal,
Purna Chandra <[email protected]>; Maheshwari, Abhishek
<[email protected]>
Subject: [PATCH v5] vdpa/ifc/base: wait for queue disable before saving q-state
Some ifc hardware require synchronization between disabling a queue and saving
queue-state from LM registers. When queue is disabled from vDPA driver, ifc
device stops executing new virtio-cmds and then updates LM registers with
used/avail index. Before saving the queue-state, vDPA driver should wait until
the queue is disabled from backend.
Fixes: 5d75517beffe ("vdpa/ifc/base: access block device registers")
Cc: [email protected]
Signed-off-by: Abhishek Maheshwari <[email protected]>
---
v2:
* Fixing the styling issues
* Addressing comment to avoid reading the register again after
exhausting the tries
v3:
* Fixing warning condition
v4:
* Fixing print argument format to %u in warning
v5:
* Addressing comments based on input that line length limit is 100
---
drivers/vdpa/ifc/base/ifcvf.c | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/drivers/vdpa/ifc/base/ifcvf.c b/drivers/vdpa/ifc/base/ifcvf.c
index f1e1474447..60555a6786 100644
--- a/drivers/vdpa/ifc/base/ifcvf.c
+++ b/drivers/vdpa/ifc/base/ifcvf.c
@@ -257,6 +257,7 @@ ifcvf_hw_disable(struct ifcvf_hw *hw)
u32 i;
struct ifcvf_pci_common_cfg *cfg;
u32 ring_state;
+ int q_disable_try;
cfg = hw->common_cfg;
if (!cfg) {
@@ -275,6 +276,20 @@ ifcvf_hw_disable(struct ifcvf_hw *hw)
continue;
}
+ /* Some ifc hardware require synchronization between disabling a
+ * queue and saving queue-state from LM registers. When queue is
+ * disabled from vDPA driver, ifc device stops executing new
+ * virtio-cmds and then updates LM registers with used/avail
+ * index. Before saving the queue-state, vDPA driver waits until
+ * the queue is disabled from backend.
+ */
+ q_disable_try = 10;
+ while (q_disable_try-- && IFCVF_READ_REG16(&cfg->queue_enable))
+ msec_delay(10);
+
+ if (!q_disable_try)
+ WARNINGOUT("Failed to disable Q:%u, Saved state could
be invalid\n",
+i);
+
if (hw->device_type == IFCVF_BLK)
ring_state = *(u32 *)(hw->lm_cfg +
IFCVF_LM_RING_STATE_OFFSET +
--
2.31.1
Ack. Reviewed by Purna Chandra Mandal <purna.chandra,[email protected]>
