[PATCH net-next v9 6/7] ixgbevf: Add RSS Key query code

[Vlad Zolotarov <vladz@cloudius-systems.com>]

Add the ixgbevf_get_rss_key() function that queries the PF for an RSS Random Key
using a new VF-PF channel IXGBE_VF_GET_RSS_KEY command.

This patch adds the support for 82599 and x540 devices only. Support for other
devices will be added later.

Signed-off-by: Vlad Zolotarov <vladz@cloudius-systems.com>
---
New in v9:
   - Reduce the support to 82599 and x540 devices only.
   - Added IXGBEVF_RSS_HASH_KEY_SIZE macro.

New in v8:
   - Protect a mailbox access.

New in v6:
   - Return a proper return code when an operation is blocked by PF.

New in v2:
   - Added a more detailed patch description.

New in v1 (compared to RFC):
   - Use "if-else" statement instead of a "switch-case" for a single option case
     (in ixgbevf_get_rss_key()).
---
 drivers/net/ethernet/intel/ixgbevf/ixgbevf.h |  1 +
 drivers/net/ethernet/intel/ixgbevf/mbx.h     |  1 +
 drivers/net/ethernet/intel/ixgbevf/vf.c      | 66 ++++++++++++++++++++++++++++
 drivers/net/ethernet/intel/ixgbevf/vf.h      |  1 +
 4 files changed, 69 insertions(+)

diff --git a/drivers/net/ethernet/intel/ixgbevf/ixgbevf.h b/drivers/net/ethernet/intel/ixgbevf/ixgbevf.h
index bc939a1..6771ae3 100644
--- a/drivers/net/ethernet/intel/ixgbevf/ixgbevf.h
+++ b/drivers/net/ethernet/intel/ixgbevf/ixgbevf.h
@@ -145,6 +145,7 @@ struct ixgbevf_ring {
 #define MAX_RX_QUEUES IXGBE_VF_MAX_RX_QUEUES
 #define MAX_TX_QUEUES IXGBE_VF_MAX_TX_QUEUES
 #define IXGBEVF_MAX_RSS_QUEUES	2
+#define IXGBEVF_RSS_HASH_KEY_SIZE	40
 
 #define IXGBEVF_DEFAULT_TXD	1024
 #define IXGBEVF_DEFAULT_RXD	512
diff --git a/drivers/net/ethernet/intel/ixgbevf/mbx.h b/drivers/net/ethernet/intel/ixgbevf/mbx.h
index 66e138b..82f44e0 100644
--- a/drivers/net/ethernet/intel/ixgbevf/mbx.h
+++ b/drivers/net/ethernet/intel/ixgbevf/mbx.h
@@ -110,6 +110,7 @@ enum ixgbe_pfvf_api_rev {
 
 /* mailbox API, version 1.2 VF requests */
 #define IXGBE_VF_GET_RETA	0x0a	/* VF request for RETA */
+#define IXGBE_VF_GET_RSS_KEY	0x0b	/* get RSS hash key */
 
 /* length of permanent address message returned from PF */
 #define IXGBE_VF_PERMADDR_MSG_LEN	4
diff --git a/drivers/net/ethernet/intel/ixgbevf/vf.c b/drivers/net/ethernet/intel/ixgbevf/vf.c
index 2676c0b..ec68145 100644
--- a/drivers/net/ethernet/intel/ixgbevf/vf.c
+++ b/drivers/net/ethernet/intel/ixgbevf/vf.c
@@ -301,6 +301,72 @@ static inline int ixgbevf_get_reta_locked(struct ixgbe_hw *hw, u32 *msgbuf,
 	return 0;
 }
 
+static inline int ixgbevf_get_rss_key_locked(struct ixgbe_hw *hw, u8 *rss_key)
+{
+	int err;
+	u32 msgbuf[IXGBE_VFMAILBOX_SIZE];
+
+	/* We currently support the RSS Random Key retrieval for 82599 and x540
+	 * devices only.
+	 *
+	 * Thus return an error if API doesn't support RSS Random Key retrieval
+	 * or if the operation is not supported for this device type.
+	 */
+	if (hw->api_version != ixgbe_mbox_api_12 ||
+	    hw->mac.type >= ixgbe_mac_X550_vf)
+		return -EPERM;
+
+	msgbuf[0] = IXGBE_VF_GET_RSS_KEY;
+	err = hw->mbx.ops.write_posted(hw, msgbuf, 1);
+
+	if (err)
+		return err;
+
+	err = hw->mbx.ops.read_posted(hw, msgbuf, 11);
+
+	if (err)
+		return err;
+
+	msgbuf[0] &= ~IXGBE_VT_MSGTYPE_CTS;
+
+	/* If the operation has been refused by a PF return -EPERM */
+	if (msgbuf[0] == (IXGBE_VF_GET_RETA | IXGBE_VT_MSGTYPE_NACK))
+		return -EPERM;
+
+	/* If we didn't get an ACK there must have been
+	 * some sort of mailbox error so we should treat it
+	 * as such.
+	 */
+	if (msgbuf[0] != (IXGBE_VF_GET_RSS_KEY | IXGBE_VT_MSGTYPE_ACK))
+		return IXGBE_ERR_MBX;
+
+	memcpy(rss_key, msgbuf + 1, IXGBEVF_RSS_HASH_KEY_SIZE);
+
+	return 0;
+}
+
+/**
+ * ixgbevf_get_rss_key - get the RSS Random Key
+ * @hw: pointer to the HW structure
+ * @reta: buffer to fill with RETA contents.
+ *
+ * The "rss_key" buffer should be big enough to contain 10 registers.
+ * Ensures the atomicy of a mailbox access using the adapter.mbx_lock spinlock.
+ *
+ * Returns: 0 on success.
+ *          if API doesn't support this operation - (-EPERM).
+ */
+int ixgbevf_get_rss_key(struct ixgbevf_adapter *a, u8 *rss_key)
+{
+	int rc;
+
+	spin_lock_bh(&a->mbx_lock);
+	rc = ixgbevf_get_rss_key_locked(&a->hw, rss_key);
+	spin_unlock_bh(&a->mbx_lock);
+
+	return rc;
+}
+
 /**
  * ixgbevf_get_reta - get the RSS redirection table (RETA) contents.
  * @adapter: pointer to the port handle
diff --git a/drivers/net/ethernet/intel/ixgbevf/vf.h b/drivers/net/ethernet/intel/ixgbevf/vf.h
index 7944962..a054716 100644
--- a/drivers/net/ethernet/intel/ixgbevf/vf.h
+++ b/drivers/net/ethernet/intel/ixgbevf/vf.h
@@ -212,4 +212,5 @@ int ixgbevf_negotiate_api_version(struct ixgbe_hw *hw, int api);
 int ixgbevf_get_queues(struct ixgbe_hw *hw, unsigned int *num_tcs,
 		       unsigned int *default_tc);
 int ixgbevf_get_reta(struct ixgbevf_adapter *adapter, u32 *reta);
+int ixgbevf_get_rss_key(struct ixgbevf_adapter *adapter, u8 *rss_key);
 #endif /* __IXGBE_VF_H__ */
-- 
2.1.0