vdpa/snet: support getting and setting VQ state

This patch adds the get_vq_state and set_vq_state vDPA callbacks.

In order to get the VQ state, the state needs to be read from the DPU.
In order to allow that, the old messaging mechanism is replaced with a new,
flexible control mechanism.
This mechanism allows to read data from the DPU.

The mechanism can be used if the negotiated config version is 2 or
higher.

If the new mechanism is used when the config version is 1, it will call
snet_send_ctrl_msg_old, which is config 1 compatible.

Signed-off-by: Alvaro Karsz <alvaro.karsz@solid-run.com>
Message-Id: <20230413073337.31367-2-alvaro.karsz@solid-run.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Jason Wang <jasowang@redhat.com>

1 files changed, 45 insertions, 67 deletions

diff --git a/drivers/vdpa/solidrun/snet_main.c b/drivers/vdpa/solidrun/snet_main.c
index 68de727398ed..86769f436b4d 100644
--- a/drivers/vdpa/solidrun/snet_main.c
+++ b/drivers/vdpa/solidrun/snet_main.c
@@ -2,7 +2,7 @@
 /*
  * SolidRun DPU driver for control plane
  *
- * Copyright (C) 2022 SolidRun
+ * Copyright (C) 2022-2023 SolidRun
  *
  * Author: Alvaro Karsz <alvaro.karsz@solid-run.com>
  *
@@ -16,14 +16,12 @@
 /* SNET signature */
 #define SNET_SIGNATURE          0xD0D06363
 /* Max. config version that we can work with */
-#define SNET_CFG_VERSION        0x1
+#define SNET_CFG_VERSION        0x2
 /* Queue align */
 #define SNET_QUEUE_ALIGNMENT    PAGE_SIZE
 /* Kick value to notify that new data is available */
 #define SNET_KICK_VAL           0x1
 #define SNET_CONFIG_OFF         0x0
-/* ACK timeout for a message */
-#define SNET_ACK_TIMEOUT	2000000
 /* How long we are willing to wait for a SNET device */
 #define SNET_DETECT_TIMEOUT	5000000
 /* How long should we wait for the DPU to read our config */
@@ -32,56 +30,11 @@
 #define SNET_GENERAL_CFG_LEN	36
 #define SNET_GENERAL_CFG_VQ_LEN	40
 
-enum snet_msg {
-	SNET_MSG_DESTROY = 1,
-};
-
 static struct snet *vdpa_to_snet(struct vdpa_device *vdpa)
 {
 	return container_of(vdpa, struct snet, vdpa);
 }
 
-static int snet_wait_for_msg_ack(struct snet *snet)
-{
-	struct pci_dev *pdev = snet->pdev;
-	int ret;
-	u32 val;
-
-	/* The DPU will clear the messages offset once messages
-	 * are processed.
-	 */
-	ret = readx_poll_timeout(ioread32, snet->bar + snet->psnet->cfg.msg_off,
-				 val, !val, 10, SNET_ACK_TIMEOUT);
-	if (ret)
-		SNET_WARN(pdev, "Timeout waiting for message ACK\n");
-
-	return ret;
-}
-
-/* Sends a message to the DPU.
- * If blocking is set, the function will return once the
- * message was processed by the DPU (or timeout).
- */
-static int snet_send_msg(struct snet *snet, u32 msg, bool blocking)
-{
-	int ret = 0;
-
-	/* Make sure the DPU acked last message before issuing a new one */
-	ret = snet_wait_for_msg_ack(snet);
-	if (ret)
-		return ret;
-
-	/* Write the message */
-	snet_write32(snet, snet->psnet->cfg.msg_off, msg);
-
-	if (blocking)
-		ret = snet_wait_for_msg_ack(snet);
-	else /* If non-blocking, flush the write by issuing a read */
-		snet_read32(snet, snet->psnet->cfg.msg_off);
-
-	return ret;
-}
-
 static irqreturn_t snet_cfg_irq_hndlr(int irq, void *data)
 {
 	struct snet *snet = data;
@@ -181,33 +134,48 @@ static bool snet_get_vq_ready(struct vdpa_device *vdev, u16 idx)
 	return snet->vqs[idx]->ready;
 }
 
-static int snet_set_vq_state(struct vdpa_device *vdev, u16 idx, const struct vdpa_vq_state *state)
+static bool snet_vq_state_is_initial(struct snet *snet, const struct vdpa_vq_state *state)
 {
-	struct snet *snet = vdpa_to_snet(vdev);
-	/* Setting the VQ state is not supported.
-	 * If the asked state is the same as the initial one
-	 * we can ignore it.
-	 */
 	if (SNET_HAS_FEATURE(snet, VIRTIO_F_RING_PACKED)) {
 		const struct vdpa_vq_state_packed *p = &state->packed;
 
 		if (p->last_avail_counter == 1 && p->last_used_counter == 1 &&
 		    p->last_avail_idx == 0 && p->last_used_idx == 0)
-			return 0;
+			return true;
 	} else {
 		const struct vdpa_vq_state_split *s = &state->split;
 
 		if (s->avail_index == 0)
-			return 0;
+			return true;
+	}
+
+	return false;
+}
+
+static int snet_set_vq_state(struct vdpa_device *vdev, u16 idx, const struct vdpa_vq_state *state)
+{
+	struct snet *snet = vdpa_to_snet(vdev);
+
+	/* We can set any state for config version 2+ */
+	if (SNET_CFG_VER(snet, 2)) {
+		memcpy(&snet->vqs[idx]->vq_state, state, sizeof(*state));
+		return 0;
 	}
 
+	/* Older config - we can't set the VQ state.
+	 * Return 0 only if this is the initial state we use in the DPU.
+	 */
+	if (snet_vq_state_is_initial(snet, state))
+		return 0;
+
 	return -EOPNOTSUPP;
 }
 
 static int snet_get_vq_state(struct vdpa_device *vdev, u16 idx, struct vdpa_vq_state *state)
 {
-	/* Not supported */
-	return -EOPNOTSUPP;
+	struct snet *snet = vdpa_to_snet(vdev);
+
+	return snet_read_vq_state(snet, idx, state);
 }
 
 static int snet_get_vq_irq(struct vdpa_device *vdev, u16 idx)
@@ -232,9 +200,9 @@ static int snet_reset_dev(struct snet *snet)
 	if (!snet->status)
 		return 0;
 
-	/* If DPU started, send a destroy message */
+	/* If DPU started, destroy it */
 	if (snet->status & VIRTIO_CONFIG_S_DRIVER_OK)
-		ret = snet_send_msg(snet, SNET_MSG_DESTROY, true);
+		ret = snet_destroy_dev(snet);
 
 	/* Clear VQs */
 	for (i = 0; i < snet->cfg->vq_num; i++) {
@@ -258,7 +226,7 @@ static int snet_reset_dev(struct snet *snet)
 	snet->dpu_ready = false;
 
 	if (ret)
-		SNET_WARN(pdev, "Incomplete reset to SNET[%u] device\n", snet->sid);
+		SNET_WARN(pdev, "Incomplete reset to SNET[%u] device, err: %d\n", snet->sid, ret);
 	else
 		SNET_DBG(pdev, "Reset SNET[%u] device\n", snet->sid);
 
@@ -356,7 +324,7 @@ static int snet_write_conf(struct snet *snet)
 	 * |             DESC AREA                |
 	 * |            DEVICE AREA               |
 	 * |            DRIVER AREA               |
-	 * |             RESERVED                 |
+	 * |    VQ STATE (CFG 2+)     |   RSVD    |
 	 *
 	 * Magic number should be written last, this is the DPU indication that the data is ready
 	 */
@@ -391,12 +359,15 @@ static int snet_write_conf(struct snet *snet)
 		off += 8;
 		snet_write64(snet, off, snet->vqs[i]->driver_area);
 		off += 8;
+		/* Write VQ state if config version is 2+ */
+		if (SNET_CFG_VER(snet, 2))
+			snet_write32(snet, off, *(u32 *)&snet->vqs[i]->vq_state);
+		off += 4;
+
 		/* Ignore reserved */
-		off += 8;
+		off += 4;
 	}
 
-	/* Clear snet messages address for this device */
-	snet_write32(snet, snet->psnet->cfg.msg_off, 0);
 	/* Write magic number - data is ready */
 	snet_write32(snet, snet->psnet->cfg.host_cfg_off, SNET_SIGNATURE);
 
@@ -697,7 +668,7 @@ static int psnet_read_cfg(struct pci_dev *pdev, struct psnet *psnet)
 	off += 4;
 	cfg->hwmon_off = psnet_read32(psnet, off);
 	off += 4;
-	cfg->msg_off = psnet_read32(psnet, off);
+	cfg->ctrl_off = psnet_read32(psnet, off);
 	off += 4;
 	cfg->flags = psnet_read32(psnet, off);
 	off += 4;
@@ -997,6 +968,10 @@ static int snet_vdpa_probe_vf(struct pci_dev *pdev)
 		goto free_irqs;
 	}
 
+	/* Init control mutex and spinlock */
+	mutex_init(&snet->ctrl_lock);
+	spin_lock_init(&snet->ctrl_spinlock);
+
 	/* Save pci device pointer */
 	snet->pdev = pdev;
 	snet->psnet = psnet;
@@ -1013,6 +988,9 @@ static int snet_vdpa_probe_vf(struct pci_dev *pdev)
 	/* Create a VirtIO config pointer */
 	snet->cfg->virtio_cfg = snet->bar + snet->psnet->cfg.virtio_cfg_off;
 
+	/* Clear control registers */
+	snet_ctrl_clear(snet);
+
 	pci_set_master(pdev);
 	pci_set_drvdata(pdev, snet);