[PATCH v2 2/4] net/gve: introduce extended adminq command

["Jasper Tran O'Leary" <jtranoleary@google.com>]

From: Vee Agarwal <veethebee@google.com>

Flow steering adminq commands are too large to fit into a normal adminq
command buffer which accepts at most 56 bytes. As a result, introduce
extended adminq commands which permit larger command buffers using
indirection. Namely, extended command operations point to inner command
buffers allocated at a specified DMA address. As specified with the
device, all extended commands will use inner opcodes larger than 0xFF.

Signed-off-by: Vee Agarwal <veethebee@google.com>
Signed-off-by: Jasper Tran O'Leary <jtranoleary@google.com>
Reviewed-by: Joshua Washington <joshwash@google.com>
---
 drivers/net/gve/base/gve_adminq.c | 30 ++++++++++++++++++++++++++++++
 drivers/net/gve/base/gve_adminq.h | 16 ++++++++++++++++
 2 files changed, 46 insertions(+)

diff --git a/drivers/net/gve/base/gve_adminq.c b/drivers/net/gve/base/gve_adminq.c
index 64b9468..0cc6d44 100644
--- a/drivers/net/gve/base/gve_adminq.c
+++ b/drivers/net/gve/base/gve_adminq.c
@@ -438,6 +438,8 @@ static int gve_adminq_issue_cmd(struct gve_priv *priv,
 
 	memcpy(cmd, cmd_orig, sizeof(*cmd_orig));
 	opcode = be32_to_cpu(READ_ONCE32(cmd->opcode));
+	if (opcode == GVE_ADMINQ_EXTENDED_COMMAND)
+		opcode = be32_to_cpu(READ_ONCE32(cmd->extended_command.inner_opcode));
 
 	switch (opcode) {
 	case GVE_ADMINQ_DESCRIBE_DEVICE:
@@ -516,6 +518,34 @@ static int gve_adminq_execute_cmd(struct gve_priv *priv,
 	return gve_adminq_kick_and_wait(priv);
 }
 
+static int gve_adminq_execute_extended_cmd(struct gve_priv *priv, u32 opcode,
+					   size_t cmd_size, void *cmd_orig)
+{
+	union gve_adminq_command cmd;
+	struct gve_dma_mem inner_cmd_dma_mem;
+	void *inner_cmd;
+	int err;
+
+	inner_cmd = gve_alloc_dma_mem(&inner_cmd_dma_mem, cmd_size);
+	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_dma_mem.pa),
+	};
+
+	err = gve_adminq_execute_cmd(priv, &cmd);
+
+	gve_free_dma_mem(&inner_cmd_dma_mem);
+	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/gve/base/gve_adminq.h b/drivers/net/gve/base/gve_adminq.h
index e237353..f52658e 100644
--- a/drivers/net/gve/base/gve_adminq.h
+++ b/drivers/net/gve/base/gve_adminq.h
@@ -25,8 +25,15 @@ 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,
 };
 
+/* The normal adminq command is restricted to be 56 bytes at maximum. For the
+ * longer adminq command, it is wrapped by GVE_ADMINQ_EXTENDED_COMMAND with
+ * inner opcode of gve_adminq_extended_cmd_opcodes specified. The inner command
+ * is written in the dma memory allocated by GVE_ADMINQ_EXTENDED_COMMAND.
+ */
 /* Admin queue status codes */
 enum gve_adminq_statuses {
 	GVE_ADMINQ_COMMAND_UNSET			= 0x0,
@@ -194,6 +201,14 @@ 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;
+};
+
+GVE_CHECK_STRUCT_LEN(16, gve_adminq_extended_command);
+
 struct gve_driver_info {
 	u8 os_type;	/* 0x05 = DPDK */
 	u8 driver_major;
@@ -440,6 +455,7 @@ 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];
-- 
2.53.0.473.g4a7958ca14-goog