net: mana: Support holes in device list reply msg

According to GDMA protocol, holes (zeros) are allowed at the beginning
or middle of the gdma_list_devices_resp message. The existing code
cannot properly handle this, and may miss some devices in the list.

To fix, scan the entire list until the num_of_devs are found, or until
the end of the list.

Cc: [email protected]
Fixes: ca9c54d ("net: mana: Add a driver for Microsoft Azure Network Adapter (MANA)")
Signed-off-by: Haiyang Zhang <[email protected]>
Reviewed-by: Long Li <[email protected]>
Reviewed-by: Shradha Gupta <[email protected]>
Reviewed-by: Michal Swiatkowski <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Paolo Abeni <[email protected]>

Author: haiyangz

drivers/net/ethernet/microsoft/mana/gdma_main.c

@@ -134,9 +134,10 @@ static int mana_gd_detect_devices(struct pci_dev *pdev)
 	struct gdma_list_devices_resp resp = {};
 	struct gdma_general_req req = {};
 	struct gdma_dev_id dev;
-	u32 i, max_num_devs;
+	int found_dev = 0;
 	u16 dev_type;
 	int err;
+	u32 i;
 
 	mana_gd_init_req_hdr(&req.hdr, GDMA_LIST_DEVICES, sizeof(req),
 			     sizeof(resp));
@@ -148,12 +149,17 @@ static int mana_gd_detect_devices(struct pci_dev *pdev)
 		return err ? err : -EPROTO;
 	}
 
-	max_num_devs = min_t(u32, MAX_NUM_GDMA_DEVICES, resp.num_of_devs);
-
-	for (i = 0; i < max_num_devs; i++) {
+	for (i = 0; i < GDMA_DEV_LIST_SIZE &&
+	     found_dev < resp.num_of_devs; i++) {
 		dev = resp.devs[i];
 		dev_type = dev.type;
 
+		/* Skip empty devices */
+		if (dev.as_uint32 == 0)
+			continue;
+
+		found_dev++;
+
 		/* HWC is already detected in mana_hwc_create_channel(). */
 		if (dev_type == GDMA_DEVICE_HWC)
 			continue;

include/net/mana/gdma.h

@@ -408,8 +408,6 @@ struct gdma_context {
 	struct gdma_dev		mana_ib;
 };
 
-#define MAX_NUM_GDMA_DEVICES	4
-
 static inline bool mana_gd_is_mana(struct gdma_dev *gd)
 {
 	return gd->dev_id.type == GDMA_DEVICE_MANA;
@@ -556,11 +554,15 @@ enum {
 #define GDMA_DRV_CAP_FLAG_1_HWC_TIMEOUT_RECONFIG BIT(3)
 #define GDMA_DRV_CAP_FLAG_1_VARIABLE_INDIRECTION_TABLE_SUPPORT BIT(5)
 
+/* Driver can handle holes (zeros) in the device list */
+#define GDMA_DRV_CAP_FLAG_1_DEV_LIST_HOLES_SUP BIT(11)
+
 #define GDMA_DRV_CAP_FLAGS1 \
 	(GDMA_DRV_CAP_FLAG_1_EQ_SHARING_MULTI_VPORT | \
 	 GDMA_DRV_CAP_FLAG_1_NAPI_WKDONE_FIX | \
 	 GDMA_DRV_CAP_FLAG_1_HWC_TIMEOUT_RECONFIG | \
-	 GDMA_DRV_CAP_FLAG_1_VARIABLE_INDIRECTION_TABLE_SUPPORT)
+	 GDMA_DRV_CAP_FLAG_1_VARIABLE_INDIRECTION_TABLE_SUPPORT | \
+	 GDMA_DRV_CAP_FLAG_1_DEV_LIST_HOLES_SUP)
 
 #define GDMA_DRV_CAP_FLAGS2 0
 
@@ -621,11 +623,12 @@ struct gdma_query_max_resources_resp {
 }; /* HW DATA */
 
 /* GDMA_LIST_DEVICES */
+#define GDMA_DEV_LIST_SIZE 64
 struct gdma_list_devices_resp {
 	struct gdma_resp_hdr hdr;
 	u32 num_of_devs;
 	u32 reserved;
-	struct gdma_dev_id devs[64];
+	struct gdma_dev_id devs[GDMA_DEV_LIST_SIZE];
 }; /* HW DATA */
 
 /* GDMA_REGISTER_DEVICE */