On Mon,  1 Jul 2019 15:57:52 -0700, Catherine Sullivan wrote:

Add a driver framework for the Compute Engine Virtual NIC that will be
available in the future.

At this point the only functionality is loading the driver.

Signed-off-by: Catherine Sullivan <redacted>
Signed-off-by: Sagi Shahar <redacted>
Signed-off-by: Jon Olson <redacted>
Acked-by: Willem de Bruijn <willemb@google.com>
Reviewed-by: Luigi Rizzo <redacted>

+Admin Queue (AQ)
+----------------
+The Admin Queue is a PAGE_SIZE memory block, treated as an array of AQ
+commands, used by the driver to issue commands to the device and set up
+resources.The driver and the device maintain a count of how many commands
+have been submitted and executed. To issue AQ commands, the driver must do
+the following (with proper locking):
+
+1)  Copy new commands into next available slots in the AQ array
+2)  Increment its counter by he number of new commands

s/he/the/

+3)  Write the counter into the GVE_ADMIN_QUEUE_DOORBELL register
+4)  Poll the ADMIN_QUEUE_EVENT_COUNTER register until it equals
+    the value written to the doorbell, or until a timeout.
+
+The device will update the status field in each AQ command reported as
+executed through the ADMIN_QUEUE_EVENT_COUNTER register.
+

+/* This function is not threadsafe - the caller is responsible for any
+ * necessary locks.
+ */
+int gve_adminq_execute_cmd(struct gve_priv *priv,
+			   union gve_adminq_command *cmd_orig)
+{
+	union gve_adminq_command *cmd;
+	u32 status = 0;
+	u32 prod_cnt;
+
+	cmd = &priv->adminq[priv->adminq_prod_cnt & priv->adminq_mask];
+	priv->adminq_prod_cnt++;
+	prod_cnt = priv->adminq_prod_cnt;
+
+	memcpy(cmd, cmd_orig, sizeof(*cmd_orig));

Eh, I guess you don't even need memory barriers around the data movement
to the DMA buffer because of the restriction to x86? :)

+	gve_adminq_kick_cmd(priv, prod_cnt);
+	if (!gve_adminq_wait_for_cmd(priv, prod_cnt)) {
+		dev_err(&priv->pdev->dev, "AQ command timed out, need to reset AQ\n");
+		return -ENOTRECOVERABLE;
+	}

+	memcpy(cmd_orig, cmd, sizeof(*cmd));
+	status = be32_to_cpu(READ_ONCE(cmd->status));
+	return gve_adminq_parse_err(&priv->pdev->dev, status);
+}

+int gve_adminq_describe_device(struct gve_priv *priv)
+{
+	struct gve_device_descriptor *descriptor;
+	union gve_adminq_command cmd;
+	dma_addr_t descriptor_bus;
+	int err = 0;
+	u8 *mac;
+	u16 mtu;
+
+	memset(&cmd, 0, sizeof(cmd));
+	descriptor = dma_alloc_coherent(&priv->pdev->dev, PAGE_SIZE,
+					&descriptor_bus, GFP_KERNEL);
+	if (!descriptor)
+		return -ENOMEM;
+	cmd.opcode = cpu_to_be32(GVE_ADMINQ_DESCRIBE_DEVICE);
+	cmd.describe_device.device_descriptor_addr =
+						cpu_to_be64(descriptor_bus);
+	cmd.describe_device.device_descriptor_version =
+			cpu_to_be32(GVE_ADMINQ_DEVICE_DESCRIPTOR_VERSION);
+	cmd.describe_device.available_length = cpu_to_be32(PAGE_SIZE);
+
+	err = gve_adminq_execute_cmd(priv, &cmd);
+	if (err)
+		goto free_device_descriptor;
+
+	mtu = be16_to_cpu(descriptor->mtu);
+	if (mtu < ETH_MIN_MTU) {
+		netif_err(priv, drv, priv->dev, "MTU %d below minimum MTU\n",
+			  mtu);
+		err = -EINVAL;
+		goto free_device_descriptor;
+	}
+	priv->dev->max_mtu = mtu;
+	priv->num_event_counters = be16_to_cpu(descriptor->counters);
+	ether_addr_copy(priv->dev->dev_addr, descriptor->mac);

Since you check MTU you can check the address with
is_valid_ether_addr().

Also it's common practice to copy the provisioned MAC to
netdev->perm_addr as well as dev_addr for VFs.

+	mac = descriptor->mac;
+	netif_info(priv, drv, priv->dev, "MAC addr: %pM\n", mac);
+
+free_device_descriptor:
+	dma_free_coherent(&priv->pdev->dev, sizeof(*descriptor), descriptor,
+			  descriptor_bus);
+	return err;
+}

Oh, okay, David already applied..