[gve] Parse option list returned in device descriptor

Provide space for the device to return its list of supported options.
Parse the option list and record the existence of each option in a
support bitmask.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

src/drivers/net/gve.h

@@ -155,10 +155,48 @@ struct gve_device_descriptor {
 	uint8_t reserved_c[4];
 	/** MAC address */
 	struct google_mac mac;
+	/** Number of device options */
+	uint16_t opt_count;
+	/** Total length (including this header) */
+	uint16_t len;
 	/** Reserved */
-	uint8_t reserved_d[10];
+	uint8_t reserved_d[6];
+	/** Space for options
+	 *
+	 * There is no specified upper limit, and no negotiation
+	 * mechanism for the amount of space required.  We allow space
+	 * for seems like a reasonable number of options.
+	 */
+	uint8_t opts[216];
 } __attribute__ (( packed ));
 
+/** Device option header */
+struct gve_option {
+	/** Option ID */
+	uint16_t id;
+	/** Length (excluding this header) */
+	uint16_t len;
+	/** Required feature mask
+	 *
+	 * The purpose of this field is remarkably unclear.  The Linux
+	 * kernel driver does define enum gve_dev_opt_req_feat_mask,
+	 * but every member of this enum has a zero value.
+	 */
+	uint32_t required;
+} __attribute__ (( packed ));
+
+/** In-order descriptor queues with raw DMA addressing */
+#define GVE_OPT_GQI_RDA 0x02
+
+/** In-order descriptor queues with queue page list addressing */
+#define GVE_OPT_GQI_QPL 0x03
+
+/** Out-of-order descriptor queues with raw DMA addressing */
+#define GVE_OPT_DQO_RDA 0x04
+
+/** Out-of-order descriptor queues with queue page list addressing */
+#define GVE_OPT_DQO_QPL 0x07
+
 /** Configure device resources command */
 #define GVE_ADMIN_CONFIGURE 0x0002
 
@@ -663,6 +701,8 @@ struct gve_nic {
 	struct gve_events events;
 	/** Scratch buffer */
 	struct gve_scratch scratch;
+	/** Supported options */
+	uint32_t options;
 
 	/** Transmit queue */
 	struct gve_queue tx;