[PATCH net-next v2 2/5] gve: Add adminq extended command

[Ziwei Xiao <ziweixiao@google.com>]

From: Jeroen de Borst <jeroendb@google.com>

The adminq command is limited to 64 bytes per entry and it's 56 bytes
for the command itself at maximum. To support larger commands, we need
to dma_alloc a separate memory to put the command in that memory and
send the dma memory address instead of the actual command.

Introduce an extended adminq command to wrap the real command with the
inner opcode and the allocated dma memory address specified. Once the
device receives it, it can get the real command from the given dma
memory address. As designed with the device, all the extended commands
will use inner opcode larger than 0xFF.

Signed-off-by: Jeroen de Borst <jeroendb@google.com>
Co-developed-by: Ziwei Xiao <ziweixiao@google.com>
Signed-off-by: Ziwei Xiao <ziweixiao@google.com>
Reviewed-by: Praveen Kaligineedi <pkaligineedi@google.com>
Reviewed-by: Harshitha Ramamurthy <hramamurthy@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
---
Changes in v2:
	- Update the commit message to use imperative mood 
	- Add the __maybe_unused attribute for the unused function of
	  gve_adminq_execute_extended_cmd

 drivers/net/ethernet/google/gve/gve_adminq.c | 31 ++++++++++++++++++++
 drivers/net/ethernet/google/gve/gve_adminq.h | 12 ++++++++
 2 files changed, 43 insertions(+)

diff --git a/drivers/net/ethernet/google/gve/gve_adminq.c b/drivers/net/ethernet/google/gve/gve_adminq.c
index 2e0c1eb87b11..5b54ce369eb2 100644
--- a/drivers/net/ethernet/google/gve/gve_adminq.c
+++ b/drivers/net/ethernet/google/gve/gve_adminq.c
@@ -461,6 +461,8 @@ static int gve_adminq_issue_cmd(struct gve_priv *priv,
 
 	memcpy(cmd, cmd_orig, sizeof(*cmd_orig));
 	opcode = be32_to_cpu(READ_ONCE(cmd->opcode));
+	if (opcode == GVE_ADMINQ_EXTENDED_COMMAND)
+		opcode = be32_to_cpu(cmd->extended_command.inner_opcode);
 
 	switch (opcode) {
 	case GVE_ADMINQ_DESCRIBE_DEVICE:
@@ -537,6 +539,35 @@ static int gve_adminq_execute_cmd(struct gve_priv *priv,
 	return err;
 }
 
+static int __maybe_unused gve_adminq_execute_extended_cmd(struct gve_priv *priv, u32 opcode,
+							  size_t cmd_size, void *cmd_orig)
+{
+	union gve_adminq_command cmd;
+	dma_addr_t inner_cmd_bus;
+	void *inner_cmd;
+	int err;
+
+	inner_cmd = dma_alloc_coherent(&priv->pdev->dev, cmd_size,
+				       &inner_cmd_bus, GFP_KERNEL);
+	if (!inner_cmd)
+		return -ENOMEM;
+
+	memcpy(inner_cmd, cmd_orig, cmd_size);
+
+	memset(&cmd, 0, sizeof(cmd));
+	cmd.opcode = cpu_to_be32(GVE_ADMINQ_EXTENDED_COMMAND);
+	cmd.extended_command = (struct gve_adminq_extended_command) {
+		.inner_opcode = cpu_to_be32(opcode),
+		.inner_length = cpu_to_be32(cmd_size),
+		.inner_command_addr = cpu_to_be64(inner_cmd_bus),
+	};
+
+	err = gve_adminq_execute_cmd(priv, &cmd);
+
+	dma_free_coherent(&priv->pdev->dev, cmd_size, inner_cmd, inner_cmd_bus);
+	return err;
+}
+
 /* The device specifies that the management vector can either be the first irq
  * or the last irq. ntfy_blk_msix_base_idx indicates the first irq assigned to
  * the ntfy blks. It if is 0 then the management vector is last, if it is 1 then
diff --git a/drivers/net/ethernet/google/gve/gve_adminq.h b/drivers/net/ethernet/google/gve/gve_adminq.h
index e64f0dbe744d..e0370ace8397 100644
--- a/drivers/net/ethernet/google/gve/gve_adminq.h
+++ b/drivers/net/ethernet/google/gve/gve_adminq.h
@@ -25,6 +25,9 @@ enum gve_adminq_opcodes {
 	GVE_ADMINQ_REPORT_LINK_SPEED		= 0xD,
 	GVE_ADMINQ_GET_PTYPE_MAP		= 0xE,
 	GVE_ADMINQ_VERIFY_DRIVER_COMPATIBILITY	= 0xF,
+
+	/* For commands that are larger than 56 bytes */
+	GVE_ADMINQ_EXTENDED_COMMAND		= 0xFF,
 };
 
 /* Admin queue status codes */
@@ -208,6 +211,14 @@ enum gve_driver_capbility {
 #define GVE_DRIVER_CAPABILITY_FLAGS3 0x0
 #define GVE_DRIVER_CAPABILITY_FLAGS4 0x0
 
+struct gve_adminq_extended_command {
+	__be32 inner_opcode;
+	__be32 inner_length;
+	__be64 inner_command_addr;
+};
+
+static_assert(sizeof(struct gve_adminq_extended_command) == 16);
+
 struct gve_driver_info {
 	u8 os_type;	/* 0x01 = Linux */
 	u8 driver_major;
@@ -432,6 +443,7 @@ union gve_adminq_command {
 			struct gve_adminq_get_ptype_map get_ptype_map;
 			struct gve_adminq_verify_driver_compatibility
 						verify_driver_compatibility;
+			struct gve_adminq_extended_command extended_command;
 		};
 	};
 	u8 reserved[64];
-- 
2.45.2.627.g7a2c4fd464-goog