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* [PATCH] vdpa/ifc/base: wait for queue disable before saving q-state
@ 2022-10-25  7:51 Abhishek Maheshwari
  2022-10-26  5:32 ` Maxime Coquelin
  0 siblings, 1 reply; 3+ messages in thread
From: Abhishek Maheshwari @ 2022-10-25  7:51 UTC (permalink / raw)
  To: xiao.w.wang, chenbo.xia; +Cc: abhishek.maheshwari, dev, purna.chandra.mandal

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.

Signed-off-by: Abhishek Maheshwari <abhishek.maheshwari@intel.com>
---
 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..76690c1f55 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_tries;
 
 	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_tries = 10;
+		while (q_disable_tries-- && IFCVF_READ_REG16(&cfg->queue_enable))
+			msec_delay(10);
+
+		if (IFCVF_READ_REG16(&cfg->queue_enable))
+			WARNINGOUT("Failed Q disable: %d. saved state is invalid\n", i);
+
 		if (hw->device_type == IFCVF_BLK)
 			ring_state = *(u32 *)(hw->lm_cfg +
 					IFCVF_LM_RING_STATE_OFFSET +
-- 
2.31.1


^ permalink raw reply	[flat|nested] 3+ messages in thread
* [PATCH] vdpa/ifc/base: wait for queue disable before saving q-state
@ 2022-10-25  7:23 Abhishek Maheshwari
  0 siblings, 0 replies; 3+ messages in thread
From: Abhishek Maheshwari @ 2022-10-25  7:23 UTC (permalink / raw)
  To: abhishek.maheshwari; +Cc: dev, chenbo.xia, purna.chandra.mandal

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.

Signed-off-by: Abhishek Maheshwari <abhishek.maheshwari@intel.com>
---
 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..fb51c793a2 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_tries;
 
 	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_tries = 10;
+		while (q_disable_tries-- && IFCVF_READ_REG16(&cfg->queue_enable))
+			msec_delay(10);
+
+		if (IFCVF_READ_REG16(&cfg->queue_enable))
+			WARNINGOUT("Failed Q disable: %d. saved state is invalid\n", i);
+
 		if (hw->device_type == IFCVF_BLK)
 			ring_state = *(u32 *)(hw->lm_cfg +
 					IFCVF_LM_RING_STATE_OFFSET +
-- 
2.31.1


^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2022-10-26  5:32 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2022-10-25  7:51 [PATCH] vdpa/ifc/base: wait for queue disable before saving q-state Abhishek Maheshwari
2022-10-26  5:32 ` Maxime Coquelin
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2022-10-25  7:23 Abhishek Maheshwari

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