net/mlx4_core: Implement the master-slave communication channel

When SRIOV is enabled, pf and vfs communicate via shared comm channel.
The vf gets its side of the comm channel via a VF BAR.
Each VF (slave) creates its vHCR (virtual HCA Command Register),
Its DMA address is passed to the PF (master) using Communication Channel Register.
The same Register is used to notify the master of commands posted by the
slaves and for the master to pass events to the slaves, such as command completions
and asynchronous events.

The vHCR format is identical to the HCR format, except for the 'go' and 't' bits,
which are reserved in the vHCR. Posting commands to the vHCR is identical to
the way it is done with the HCR, albeit that the function/PF token fields are
used instead of the HCR go bit.
Specifically:
- When the function prepares a new command in the vHCR, it issues the Post_vHCR_cmd
  communication channel command and toggles the value of the function token;
  when PF token has an equal value, the command has been accepted and a new command may be posted.
- When the PF detects a Post_vHCR_cmd command, it concludes that a new command is available in the vHCR;
  after processing the command, the PF toggles the PF token to match the function token.

When the 'e' bit is not set, the completion of a Post_vHCR_cmd command also indicates
the completion the vHCR command. If, however, the 'e' bit is set, the completion of a
Post_vHCR_cmd command only indicates that the vHCR command has been accepted for execution by the PF.

Function commands are processed by the PF as follows:
-DMA (using the ACCESS_MEM command) the vHCR image into a shadow buffer.
-Validate that the opcode is non-privileged, and that the opcode- and input-modifiers are legal.
-DMA the in-box (if required) into a shadow buffer.
-Validate the command:
	o Resource ranges (e.g., QP ranges).
	o Partition key.
	o Ranges of referenced resources (e.g., CQs within QP contexts).
-If the 'e' bit is set
	o complete the Post_vHCR_cmd command
-Execute the command on the HCR.
-DMA the results to the vHCR out-box (if required).
-If the 'e' bit is set
	o Indicate command completion by generating a completion event using the GEN_EQE command
-Otherwise
	o DMA the command status to the vHCR
	o Complete the Post_vHCR_cmd command

Signed-off-by: Jack Morgenstein <jackm@dev.mellanox.co.il>
Signed-off-by: Yevgeny Petrillin <yevgenyp@mellanox.com>
Signed-off-by: Liran Liss <liranl@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/mellanox/mlx4/cmd.c

@@ -39,12 +39,18 @@
 #include <linux/errno.h>
 
 #include <linux/mlx4/cmd.h>
+#include <linux/semaphore.h>
 
 #include <asm/io.h>
 
 #include "mlx4.h"
+#include "fw.h"
 
 #define CMD_POLL_TOKEN 0xffff
+#define INBOX_MASK	0xffffffffffffff00ULL
+
+#define CMD_CHAN_VER 1
+#define CMD_CHAN_IF_REV 1
 
 enum {
 	/* command completed successfully: */
@@ -110,8 +116,12 @@ struct mlx4_cmd_context {
 	int			next;
 	u64			out_param;
 	u16			token;
+	u8			fw_status;
 };
 
+static int mlx4_master_process_vhcr(struct mlx4_dev *dev, int slave,
+				    struct mlx4_vhcr_cmd *in_vhcr);
+
 static int mlx4_status_to_errno(u8 status)
 {
 	static const int trans_table[] = {
@@ -142,6 +152,125 @@ static int mlx4_status_to_errno(u8 status)
 	return trans_table[status];
 }
 
+static int comm_pending(struct mlx4_dev *dev)
+{
+	struct mlx4_priv *priv = mlx4_priv(dev);
+	u32 status = readl(&priv->mfunc.comm->slave_read);
+
+	return (swab32(status) >> 31) != priv->cmd.comm_toggle;
+}
+
+static void mlx4_comm_cmd_post(struct mlx4_dev *dev, u8 cmd, u16 param)
+{
+	struct mlx4_priv *priv = mlx4_priv(dev);
+	u32 val;
+
+	priv->cmd.comm_toggle ^= 1;
+	val = param | (cmd << 16) | (priv->cmd.comm_toggle << 31);
+	__raw_writel((__force u32) cpu_to_be32(val),
+		     &priv->mfunc.comm->slave_write);
+	mmiowb();
+}
+
+/* dummy procedure for this patch */
+int mlx4_GEN_EQE(struct mlx4_dev *dev, int slave, struct mlx4_eqe *eqe)
+{
+	return 0;
+}
+
+static int mlx4_comm_cmd_poll(struct mlx4_dev *dev, u8 cmd, u16 param,
+		       unsigned long timeout)
+{
+	struct mlx4_priv *priv = mlx4_priv(dev);
+	unsigned long end;
+	int err = 0;
+	int ret_from_pending = 0;
+
+	/* First, verify that the master reports correct status */
+	if (comm_pending(dev)) {
+		mlx4_warn(dev, "Communication channel is not idle."
+			  "my toggle is %d (cmd:0x%x)\n",
+			  priv->cmd.comm_toggle, cmd);
+		return -EAGAIN;
+	}
+
+	/* Write command */
+	down(&priv->cmd.poll_sem);
+	mlx4_comm_cmd_post(dev, cmd, param);
+
+	end = msecs_to_jiffies(timeout) + jiffies;
+	while (comm_pending(dev) && time_before(jiffies, end))
+		cond_resched();
+	ret_from_pending = comm_pending(dev);
+	if (ret_from_pending) {
+		/* check if the slave is trying to boot in the middle of
+		 * FLR process. The only non-zero result in the RESET command
+		 * is MLX4_DELAY_RESET_SLAVE*/
+		if ((MLX4_COMM_CMD_RESET == cmd)) {
+			mlx4_warn(dev, "Got slave FLRed from Communication"
+				  " channel (ret:0x%x)\n", ret_from_pending);
+			err = MLX4_DELAY_RESET_SLAVE;
+		} else {
+			mlx4_warn(dev, "Communication channel timed out\n");
+			err = -ETIMEDOUT;
+		}
+	}
+
+	up(&priv->cmd.poll_sem);
+	return err;
+}
+
+static int mlx4_comm_cmd_wait(struct mlx4_dev *dev, u8 op,
+			      u16 param, unsigned long timeout)
+{
+	struct mlx4_cmd *cmd = &mlx4_priv(dev)->cmd;
+	struct mlx4_cmd_context *context;
+	int err = 0;
+
+	down(&cmd->event_sem);
+
+	spin_lock(&cmd->context_lock);
+	BUG_ON(cmd->free_head < 0);
+	context = &cmd->context[cmd->free_head];
+	context->token += cmd->token_mask + 1;
+	cmd->free_head = context->next;
+	spin_unlock(&cmd->context_lock);
+
+	init_completion(&context->done);
+
+	mlx4_comm_cmd_post(dev, op, param);
+
+	if (!wait_for_completion_timeout(&context->done,
+					 msecs_to_jiffies(timeout))) {
+		err = -EBUSY;
+		goto out;
+	}
+
+	err = context->result;
+	if (err && context->fw_status != CMD_STAT_MULTI_FUNC_REQ) {
+		mlx4_err(dev, "command 0x%x failed: fw status = 0x%x\n",
+			 op, context->fw_status);
+		goto out;
+	}
+
+out:
+	spin_lock(&cmd->context_lock);
+	context->next = cmd->free_head;
+	cmd->free_head = context - cmd->context;
+	spin_unlock(&cmd->context_lock);
+
+	up(&cmd->event_sem);
+	return err;
+}
+
+static int mlx4_comm_cmd(struct mlx4_dev *dev, u8 cmd, u16 param,
+		  unsigned long timeout)
+{
+	if (mlx4_priv(dev)->cmd.use_events)
+		return mlx4_comm_cmd_wait(dev, cmd, param, timeout);
+	return mlx4_comm_cmd_poll(dev, cmd, param, timeout);
+}
+
 static int cmd_pending(struct mlx4_dev *dev)
 {
 	u32 status = readl(mlx4_priv(dev)->cmd.hcr + HCR_STATUS_OFFSET);
@@ -167,8 +296,10 @@ static int mlx4_cmd_post(struct mlx4_dev *dev, u64 in_param, u64 out_param,
 		end += msecs_to_jiffies(GO_BIT_TIMEOUT_MSECS);
 
 	while (cmd_pending(dev)) {
-		if (time_after_eq(jiffies, end))
+		if (time_after_eq(jiffies, end)) {
+			mlx4_err(dev, "%s:cmd_pending failed\n", __func__);
 			goto out;
+		}
 		cond_resched();
 	}
 
@@ -192,7 +323,7 @@ static int mlx4_cmd_post(struct mlx4_dev *dev, u64 in_param, u64 out_param,
 					       (cmd->toggle << HCR_T_BIT)	|
 					       (event ? (1 << HCR_E_BIT) : 0)	|
 					       (op_modifier << HCR_OPMOD_SHIFT) |
-					       op),			  hcr + 6);
+					       op), hcr + 6);
 
 	/*
 	 * Make sure that our HCR writes don't get mixed in with
@@ -209,6 +340,62 @@ out:
 	return ret;
 }
 
+static int mlx4_slave_cmd(struct mlx4_dev *dev, u64 in_param, u64 *out_param,
+			  int out_is_imm, u32 in_modifier, u8 op_modifier,
+			  u16 op, unsigned long timeout)
+{
+	struct mlx4_priv *priv = mlx4_priv(dev);
+	struct mlx4_vhcr_cmd *vhcr = priv->mfunc.vhcr;
+	int ret;
+
+	down(&priv->cmd.slave_sem);
+	vhcr->in_param = cpu_to_be64(in_param);
+	vhcr->out_param = out_param ? cpu_to_be64(*out_param) : 0;
+	vhcr->in_modifier = cpu_to_be32(in_modifier);
+	vhcr->opcode = cpu_to_be16((((u16) op_modifier) << 12) | (op & 0xfff));
+	vhcr->token = cpu_to_be16(CMD_POLL_TOKEN);
+	vhcr->status = 0;
+	vhcr->flags = !!(priv->cmd.use_events) << 6;
+	if (mlx4_is_master(dev)) {
+		ret = mlx4_master_process_vhcr(dev, dev->caps.function, vhcr);
+		if (!ret) {
+			if (out_is_imm) {
+				if (out_param)
+					*out_param =
+						be64_to_cpu(vhcr->out_param);
+				else {
+					mlx4_err(dev, "response expected while"
+						 "output mailbox is NULL for "
+						 "command 0x%x\n", op);
+					vhcr->status = -EINVAL;
+				}
+			}
+			ret = vhcr->status;
+		}
+	} else {
+		ret = mlx4_comm_cmd(dev, MLX4_COMM_CMD_VHCR_POST, 0,
+				    MLX4_COMM_TIME + timeout);
+		if (!ret) {
+			if (out_is_imm) {
+				if (out_param)
+					*out_param =
+						be64_to_cpu(vhcr->out_param);
+				else {
+					mlx4_err(dev, "response expected while"
+						 "output mailbox is NULL for "
+						 "command 0x%x\n", op);
+					vhcr->status = -EINVAL;
+				}
+			}
+			ret = vhcr->status;
+		} else
+			mlx4_err(dev, "failed execution of VHCR_POST command"
+				 "opcode 0x%x\n", op);
+	}
+	up(&priv->cmd.slave_sem);
+	return ret;
+}
+
 static int mlx4_cmd_poll(struct mlx4_dev *dev, u64 in_param, u64 *out_param,
 			 int out_is_imm, u32 in_modifier, u8 op_modifier,
 			 u16 op, unsigned long timeout)
@@ -217,6 +404,7 @@ static int mlx4_cmd_poll(struct mlx4_dev *dev, u64 in_param, u64 *out_param,
 	void __iomem *hcr = priv->cmd.hcr;
 	int err = 0;
 	unsigned long end;
+	u32 stat;
 
 	down(&priv->cmd.poll_sem);
 
@@ -240,9 +428,12 @@ static int mlx4_cmd_poll(struct mlx4_dev *dev, u64 in_param, u64 *out_param,
 					  __raw_readl(hcr + HCR_OUT_PARAM_OFFSET)) << 32 |
 			(u64) be32_to_cpu((__force __be32)
 					  __raw_readl(hcr + HCR_OUT_PARAM_OFFSET + 4));
-
-	err = mlx4_status_to_errno(be32_to_cpu((__force __be32)
-					       __raw_readl(hcr + HCR_STATUS_OFFSET)) >> 24);
+	stat = be32_to_cpu((__force __be32)
+			   __raw_readl(hcr + HCR_STATUS_OFFSET)) >> 24;
+	err = mlx4_status_to_errno(stat);
+	if (err)
+		mlx4_err(dev, "command 0x%x failed: fw status = 0x%x\n",
+			 op, stat);
 
 out:
 	up(&priv->cmd.poll_sem);
@@ -259,6 +450,7 @@ void mlx4_cmd_event(struct mlx4_dev *dev, u16 token, u8 status, u64 out_param)
 	if (token != context->token)
 		return;
 
+	context->fw_status = status;
 	context->result    = mlx4_status_to_errno(status);
 	context->out_param = out_param;
 
@@ -287,14 +479,18 @@ static int mlx4_cmd_wait(struct mlx4_dev *dev, u64 in_param, u64 *out_param,
 	mlx4_cmd_post(dev, in_param, out_param ? *out_param : 0,
 		      in_modifier, op_modifier, op, context->token, 1);
 
-	if (!wait_for_completion_timeout(&context->done, msecs_to_jiffies(timeout))) {
+	if (!wait_for_completion_timeout(&context->done,
+					 msecs_to_jiffies(timeout))) {
 		err = -EBUSY;
 		goto out;
 	}
 
 	err = context->result;
-	if (err)
+	if (err) {
+		mlx4_err(dev, "command 0x%x failed: fw status = 0x%x\n",
+			 op, context->fw_status);
 		goto out;
+	}
 
 	if (out_is_imm)
 		*out_param = context->out_param;
@@ -313,15 +509,448 @@ int __mlx4_cmd(struct mlx4_dev *dev, u64 in_param, u64 *out_param,
 	       int out_is_imm, u32 in_modifier, u8 op_modifier,
 	       u16 op, unsigned long timeout, int native)
 {
-	if (mlx4_priv(dev)->cmd.use_events)
-		return mlx4_cmd_wait(dev, in_param, out_param, out_is_imm,
-				     in_modifier, op_modifier, op, timeout);
-	else
-		return mlx4_cmd_poll(dev, in_param, out_param, out_is_imm,
-				     in_modifier, op_modifier, op, timeout);
+	if (!mlx4_is_mfunc(dev) || (native && mlx4_is_master(dev))) {
+		if (mlx4_priv(dev)->cmd.use_events)
+			return mlx4_cmd_wait(dev, in_param, out_param,
+					     out_is_imm, in_modifier,
+					     op_modifier, op, timeout);
+		else
+			return mlx4_cmd_poll(dev, in_param, out_param,
+					     out_is_imm, in_modifier,
+					     op_modifier, op, timeout);
+	}
+	return mlx4_slave_cmd(dev, in_param, out_param, out_is_imm,
+			      in_modifier, op_modifier, op, timeout);
 }
 EXPORT_SYMBOL_GPL(__mlx4_cmd);
 
+
+static int mlx4_ARM_COMM_CHANNEL(struct mlx4_dev *dev)
+{
+	return mlx4_cmd(dev, 0, 0, 0, MLX4_CMD_ARM_COMM_CHANNEL,
+			MLX4_CMD_TIME_CLASS_B, MLX4_CMD_NATIVE);
+}
+
+static int mlx4_ACCESS_MEM(struct mlx4_dev *dev, u64 master_addr,
+			   int slave, u64 slave_addr,
+			   int size, int is_read)
+{
+	u64 in_param;
+	u64 out_param;
+
+	if ((slave_addr & 0xfff) | (master_addr & 0xfff) |
+	    (slave & ~0x7f) | (size & 0xff)) {
+		mlx4_err(dev, "Bad access mem params - slave_addr:0x%llx "
+			      "master_addr:0x%llx slave_id:%d size:%d\n",
+			      slave_addr, master_addr, slave, size);
+		return -EINVAL;
+	}
+
+	if (is_read) {
+		in_param = (u64) slave | slave_addr;
+		out_param = (u64) dev->caps.function | master_addr;
+	} else {
+		in_param = (u64) dev->caps.function | master_addr;
+		out_param = (u64) slave | slave_addr;
+	}
+
+	return mlx4_cmd_imm(dev, in_param, &out_param, size, 0,
+			    MLX4_CMD_ACCESS_MEM,
+			    MLX4_CMD_TIME_CLASS_A, MLX4_CMD_NATIVE);
+}
+
+int mlx4_DMA_wrapper(struct mlx4_dev *dev, int slave,
+		     struct mlx4_vhcr *vhcr,
+		     struct mlx4_cmd_mailbox *inbox,
+		     struct mlx4_cmd_mailbox *outbox,
+		     struct mlx4_cmd_info *cmd)
+{
+	u64 in_param;
+	u64 out_param;
+	int err;
+
+	in_param = cmd->has_inbox ? (u64) inbox->dma : vhcr->in_param;
+	out_param = cmd->has_outbox ? (u64) outbox->dma : vhcr->out_param;
+	if (cmd->encode_slave_id) {
+		in_param &= 0xffffffffffffff00ll;
+		in_param |= slave;
+	}
+
+	err = __mlx4_cmd(dev, in_param, &out_param, cmd->out_is_imm,
+			 vhcr->in_modifier, vhcr->op_modifier, vhcr->op,
+			 MLX4_CMD_TIME_CLASS_A, MLX4_CMD_NATIVE);
+
+	if (cmd->out_is_imm)
+		vhcr->out_param = out_param;
+
+	return err;
+}
+
+static struct mlx4_cmd_info cmd_info[] = {
+	{
+		.opcode = MLX4_CMD_QUERY_FW,
+		.has_inbox = false,
+		.has_outbox = true,
+		.out_is_imm = false,
+		.encode_slave_id = false,
+		.verify = NULL,
+		.wrapper = NULL
+	},
+	{
+		.opcode = MLX4_CMD_QUERY_HCA,
+		.has_inbox = false,
+		.has_outbox = true,
+		.out_is_imm = false,
+		.encode_slave_id = false,
+		.verify = NULL,
+		.wrapper = NULL
+	},
+	{
+		.opcode = MLX4_CMD_QUERY_DEV_CAP,
+		.has_inbox = false,
+		.has_outbox = true,
+		.out_is_imm = false,
+		.encode_slave_id = false,
+		.verify = NULL,
+		.wrapper = NULL
+	},
+};
+
+static int mlx4_master_process_vhcr(struct mlx4_dev *dev, int slave,
+				    struct mlx4_vhcr_cmd *in_vhcr)
+{
+	struct mlx4_priv *priv = mlx4_priv(dev);
+	struct mlx4_cmd_info *cmd = NULL;
+	struct mlx4_vhcr_cmd *vhcr_cmd = in_vhcr ? in_vhcr : priv->mfunc.vhcr;
+	struct mlx4_vhcr *vhcr;
+	struct mlx4_cmd_mailbox *inbox = NULL;
+	struct mlx4_cmd_mailbox *outbox = NULL;
+	u64 in_param;
+	u64 out_param;
+	int ret = 0;
+	int i;
+
+	/* Create sw representation of Virtual HCR */
+	vhcr = kzalloc(sizeof(struct mlx4_vhcr), GFP_KERNEL);
+	if (!vhcr)
+		return -ENOMEM;
+
+	/* DMA in the vHCR */
+	if (!in_vhcr) {
+		ret = mlx4_ACCESS_MEM(dev, priv->mfunc.vhcr_dma, slave,
+				      priv->mfunc.master.slave_state[slave].vhcr_dma,
+				      ALIGN(sizeof(struct mlx4_vhcr_cmd),
+					    MLX4_ACCESS_MEM_ALIGN), 1);
+		if (ret) {
+			mlx4_err(dev, "%s:Failed reading vhcr"
+				 "ret: 0x%x\n", __func__, ret);
+			kfree(vhcr);
+			return ret;
+		}
+	}
+
+	/* Fill SW VHCR fields */
+	vhcr->in_param = be64_to_cpu(vhcr_cmd->in_param);
+	vhcr->out_param = be64_to_cpu(vhcr_cmd->out_param);
+	vhcr->in_modifier = be32_to_cpu(vhcr_cmd->in_modifier);
+	vhcr->token = be16_to_cpu(vhcr_cmd->token);
+	vhcr->op = be16_to_cpu(vhcr_cmd->opcode) & 0xfff;
+	vhcr->op_modifier = (u8) (be16_to_cpu(vhcr_cmd->opcode) >> 12);
+	vhcr->e_bit = vhcr_cmd->flags & (1 << 6);
+
+	/* Lookup command */
+	for (i = 0; i < ARRAY_SIZE(cmd_info); ++i) {
+		if (vhcr->op == cmd_info[i].opcode) {
+			cmd = &cmd_info[i];
+			break;
+		}
+	}
+	if (!cmd) {
+		mlx4_err(dev, "Unknown command:0x%x accepted from slave:%d\n",
+			 vhcr->op, slave);
+		vhcr_cmd->status = -EINVAL;
+		goto out_status;
+	}
+
+	/* Read inbox */
+	if (cmd->has_inbox) {
+		vhcr->in_param &= INBOX_MASK;
+		inbox = mlx4_alloc_cmd_mailbox(dev);
+		if (IS_ERR(inbox)) {
+			ret = PTR_ERR(inbox);
+			inbox = NULL;
+			goto out;
+		}
+
+		ret = mlx4_ACCESS_MEM(dev, inbox->dma, slave,
+				      vhcr->in_param,
+				      MLX4_MAILBOX_SIZE, 1);
+		if (ret) {
+			mlx4_err(dev, "%s: Failed reading inbox (cmd:0x%x)\n",
+				 __func__, cmd->opcode);
+			goto out;
+		}
+	}
+
+	/* Apply permission and bound checks if applicable */
+	if (cmd->verify && cmd->verify(dev, slave, vhcr, inbox)) {
+		mlx4_warn(dev, "Command:0x%x from slave: %d failed protection "
+			  "checks for resource_id:%d\n", vhcr->op, slave,
+			  vhcr->in_modifier);
+		vhcr_cmd->status = -EPERM;
+		goto out_status;
+	}
+
+	/* Allocate outbox */
+	if (cmd->has_outbox) {
+		outbox = mlx4_alloc_cmd_mailbox(dev);
+		if (IS_ERR(outbox)) {
+			ret = PTR_ERR(outbox);
+			outbox = NULL;
+			goto out;
+		}
+	}
+
+	/* Execute the command! */
+	if (cmd->wrapper) {
+		vhcr_cmd->status = cmd->wrapper(dev, slave, vhcr, inbox, outbox,
+					   cmd);
+		if (cmd->out_is_imm)
+			vhcr_cmd->out_param = cpu_to_be64(vhcr->out_param);
+	} else {
+		in_param = cmd->has_inbox ? (u64) inbox->dma :
+			vhcr->in_param;
+		out_param = cmd->has_outbox ? (u64) outbox->dma :
+			vhcr->out_param;
+		vhcr_cmd->status = __mlx4_cmd(dev, in_param, &out_param,
+					 cmd->out_is_imm, vhcr->in_modifier,
+					 vhcr->op_modifier, vhcr->op,
+					 MLX4_CMD_TIME_CLASS_A,
+					 MLX4_CMD_NATIVE);
+
+		if (vhcr_cmd->status) {
+			mlx4_warn(dev, "vhcr command:0x%x slave:%d failed with"
+				  " error:%d, status %d\n",
+				  vhcr->op, slave, vhcr->errno,
+				  vhcr_cmd->status);
+			ret = vhcr_cmd->status;
+			goto out;
+		}
+
+		if (cmd->out_is_imm) {
+			vhcr->out_param = out_param;
+			vhcr_cmd->out_param = cpu_to_be64(vhcr->out_param);
+		}
+	}
+
+	/* Write outbox if command completed successfully */
+	if (cmd->has_outbox && !vhcr->errno) {
+		ret = mlx4_ACCESS_MEM(dev, outbox->dma, slave,
+				      vhcr->out_param,
+				      MLX4_MAILBOX_SIZE, MLX4_CMD_WRAPPED);
+		if (ret) {
+			mlx4_err(dev, "%s:Failed writing outbox\n", __func__);
+			goto out;
+		}
+	}
+
+out_status:
+	/* DMA back vhcr result */
+	if (!in_vhcr) {
+		ret = mlx4_ACCESS_MEM(dev, priv->mfunc.vhcr_dma, slave,
+				      priv->mfunc.master.slave_state[slave].vhcr_dma,
+				      ALIGN(sizeof(struct mlx4_vhcr),
+					    MLX4_ACCESS_MEM_ALIGN),
+				      MLX4_CMD_WRAPPED);
+		if (ret)
+			mlx4_err(dev, "%s:Failed writing vhcr result\n",
+				 __func__);
+		else if (vhcr->e_bit &&
+			 mlx4_GEN_EQE(dev, slave, &priv->mfunc.master.cmd_eqe))
+				mlx4_warn(dev, "Failed to generate command completion "
+					  "eqe for slave %d\n", slave);
+	}
+
+out:
+	kfree(vhcr);
+	mlx4_free_cmd_mailbox(dev, inbox);
+	mlx4_free_cmd_mailbox(dev, outbox);
+	return ret;
+}
+
+static void mlx4_master_do_cmd(struct mlx4_dev *dev, int slave, u8 cmd,
+			       u16 param, u8 toggle)
+{
+	struct mlx4_priv *priv = mlx4_priv(dev);
+	struct mlx4_slave_state *slave_state = priv->mfunc.master.slave_state;
+	u32 reply;
+	u32 slave_status = 0;
+	u8 is_going_down = 0;
+
+	slave_state[slave].comm_toggle ^= 1;
+	reply = (u32) slave_state[slave].comm_toggle << 31;
+	if (toggle != slave_state[slave].comm_toggle) {
+		mlx4_warn(dev, "Incorrect toggle %d from slave %d. *** MASTER"
+			  "STATE COMPROMISIED ***\n", toggle, slave);
+		goto reset_slave;
+	}
+	if (cmd == MLX4_COMM_CMD_RESET) {
+		mlx4_warn(dev, "Received reset from slave:%d\n", slave);
+		slave_state[slave].active = false;
+		/*check if we are in the middle of FLR process,
+		if so return "retry" status to the slave*/
+		if (MLX4_COMM_CMD_FLR == slave_state[slave].last_cmd) {
+			slave_status = MLX4_DELAY_RESET_SLAVE;
+			goto inform_slave_state;
+		}
+
+		/* write the version in the event field */
+		reply |= mlx4_comm_get_version();
+
+		goto reset_slave;
+	}
+	/*command from slave in the middle of FLR*/
+	if (cmd != MLX4_COMM_CMD_RESET &&
+	    MLX4_COMM_CMD_FLR == slave_state[slave].last_cmd) {
+		mlx4_warn(dev, "slave:%d is Trying to run cmd(0x%x) "
+			  "in the middle of FLR\n", slave, cmd);
+		return;
+	}
+
+	switch (cmd) {
+	case MLX4_COMM_CMD_VHCR0:
+		if (slave_state[slave].last_cmd != MLX4_COMM_CMD_RESET)
+			goto reset_slave;
+		slave_state[slave].vhcr_dma = ((u64) param) << 48;
+		priv->mfunc.master.slave_state[slave].cookie = 0;
+		mutex_init(&priv->mfunc.master.gen_eqe_mutex[slave]);
+		break;
+	case MLX4_COMM_CMD_VHCR1:
+		if (slave_state[slave].last_cmd != MLX4_COMM_CMD_VHCR0)
+			goto reset_slave;
+		slave_state[slave].vhcr_dma |= ((u64) param) << 32;
+		break;
+	case MLX4_COMM_CMD_VHCR2:
+		if (slave_state[slave].last_cmd != MLX4_COMM_CMD_VHCR1)
+			goto reset_slave;
+		slave_state[slave].vhcr_dma |= ((u64) param) << 16;
+		break;
+	case MLX4_COMM_CMD_VHCR_EN:
+		if (slave_state[slave].last_cmd != MLX4_COMM_CMD_VHCR2)
+			goto reset_slave;
+		slave_state[slave].vhcr_dma |= param;
+		slave_state[slave].active = true;
+		break;
+	case MLX4_COMM_CMD_VHCR_POST:
+		if ((slave_state[slave].last_cmd != MLX4_COMM_CMD_VHCR_EN) &&
+		    (slave_state[slave].last_cmd != MLX4_COMM_CMD_VHCR_POST))
+			goto reset_slave;
+		down(&priv->cmd.slave_sem);
+		if (mlx4_master_process_vhcr(dev, slave, NULL)) {
+			mlx4_err(dev, "Failed processing vhcr for slave:%d,"
+				 " reseting slave.\n", slave);
+			up(&priv->cmd.slave_sem);
+			goto reset_slave;
+		}
+		up(&priv->cmd.slave_sem);
+		break;
+	default:
+		mlx4_warn(dev, "Bad comm cmd:%d from slave:%d\n", cmd, slave);
+		goto reset_slave;
+	}
+	spin_lock(&priv->mfunc.master.slave_state_lock);
+	if (!slave_state[slave].is_slave_going_down)
+		slave_state[slave].last_cmd = cmd;
+	else
+		is_going_down = 1;
+	spin_unlock(&priv->mfunc.master.slave_state_lock);
+	if (is_going_down) {
+		mlx4_warn(dev, "Slave is going down aborting command(%d)"
+			  " executing from slave:%d\n",
+			  cmd, slave);
+		return;
+	}
+	__raw_writel((__force u32) cpu_to_be32(reply),
+		     &priv->mfunc.comm[slave].slave_read);
+	mmiowb();
+
+	return;
+
+reset_slave:
+	spin_lock(&priv->mfunc.master.slave_state_lock);
+	if (!slave_state[slave].is_slave_going_down)
+		slave_state[slave].last_cmd = MLX4_COMM_CMD_RESET;
+	spin_unlock(&priv->mfunc.master.slave_state_lock);
+	/*with slave in the middle of flr, no need to clean resources again.*/
+inform_slave_state:
+	memset(&slave_state[slave].event_eq, 0,
+	       sizeof(struct mlx4_slave_event_eq_info));
+	__raw_writel((__force u32) cpu_to_be32(reply),
+		     &priv->mfunc.comm[slave].slave_read);
+	wmb();
+}
+
+/* master command processing */
+void mlx4_master_comm_channel(struct work_struct *work)
+{
+	struct mlx4_mfunc_master_ctx *master =
+		container_of(work,
+			     struct mlx4_mfunc_master_ctx,
+			     comm_work);
+	struct mlx4_mfunc *mfunc =
+		container_of(master, struct mlx4_mfunc, master);
+	struct mlx4_priv *priv =
+		container_of(mfunc, struct mlx4_priv, mfunc);
+	struct mlx4_dev *dev = &priv->dev;
+	__be32 *bit_vec;
+	u32 comm_cmd;
+	u32 vec;
+	int i, j, slave;
+	int toggle;
+	int served = 0;
+	int reported = 0;
+	u32 slt;
+
+	bit_vec = master->comm_arm_bit_vector;
+	for (i = 0; i < COMM_CHANNEL_BIT_ARRAY_SIZE; i++) {
+		vec = be32_to_cpu(bit_vec[i]);
+		for (j = 0; j < 32; j++) {
+			if (!(vec & (1 << j)))
+				continue;
+			++reported;
+			slave = (i * 32) + j;
+			comm_cmd = swab32(readl(
+					  &mfunc->comm[slave].slave_write));
+			slt = swab32(readl(&mfunc->comm[slave].slave_read))
+				     >> 31;
+			toggle = comm_cmd >> 31;
+			if (toggle != slt) {
+				if (master->slave_state[slave].comm_toggle
+				    != slt) {
+					printk(KERN_INFO "slave %d out of sync."
+					       " read toggle %d, state toggle %d. "
+					       "Resynching.\n", slave, slt,
+					       master->slave_state[slave].comm_toggle);
+					master->slave_state[slave].comm_toggle =
+						slt;
+				}
+				mlx4_master_do_cmd(dev, slave,
+						   comm_cmd >> 16 & 0xff,
+						   comm_cmd & 0xffff, toggle);
+				++served;
+			}
+		}
+	}
+
+	if (reported && reported != served)
+		mlx4_warn(dev, "Got command event with bitmask from %d slaves"
+			  " but %d were served\n",
+			  reported, served);
+
+	if (mlx4_ARM_COMM_CHANNEL(dev))
+		mlx4_warn(dev, "Failed to arm comm channel events\n");
+}
+
 int mlx4_cmd_init(struct mlx4_dev *dev)
 {
 	struct mlx4_priv *priv = mlx4_priv(dev);
@@ -331,22 +960,30 @@ int mlx4_cmd_init(struct mlx4_dev *dev)
 	priv->cmd.use_events = 0;
 	priv->cmd.toggle     = 1;
 
-	priv->cmd.hcr = ioremap(pci_resource_start(dev->pdev, 0) + MLX4_HCR_BASE,
-				MLX4_HCR_SIZE);
-	if (!priv->cmd.hcr) {
-		mlx4_err(dev, "Couldn't map command register.");
-		return -ENOMEM;
+	priv->cmd.hcr = NULL;
+	priv->mfunc.vhcr = NULL;
+
+	if (!mlx4_is_slave(dev)) {
+		priv->cmd.hcr = ioremap(pci_resource_start(dev->pdev, 0) +
+					MLX4_HCR_BASE, MLX4_HCR_SIZE);
+		if (!priv->cmd.hcr) {
+			mlx4_err(dev, "Couldn't map command register.\n");
+			return -ENOMEM;
+		}
 	}
 
 	priv->cmd.pool = pci_pool_create("mlx4_cmd", dev->pdev,
 					 MLX4_MAILBOX_SIZE,
 					 MLX4_MAILBOX_SIZE, 0);
-	if (!priv->cmd.pool) {
-		iounmap(priv->cmd.hcr);
-		return -ENOMEM;
-	}
+	if (!priv->cmd.pool)
+		goto err_hcr;
 
 	return 0;
+
+err_hcr:
+	if (!mlx4_is_slave(dev))
+		iounmap(priv->cmd.hcr);
+	return -ENOMEM;
 }
 
 void mlx4_cmd_cleanup(struct mlx4_dev *dev)
@@ -354,7 +991,9 @@ void mlx4_cmd_cleanup(struct mlx4_dev *dev)
 	struct mlx4_priv *priv = mlx4_priv(dev);
 
 	pci_pool_destroy(priv->cmd.pool);
-	iounmap(priv->cmd.hcr);
+
+	if (!mlx4_is_slave(dev))
+		iounmap(priv->cmd.hcr);
 }
 
 /*
@@ -365,6 +1004,7 @@ int mlx4_cmd_use_events(struct mlx4_dev *dev)
 {
 	struct mlx4_priv *priv = mlx4_priv(dev);
 	int i;
+	int err = 0;
 
 	priv->cmd.context = kmalloc(priv->cmd.max_cmds *
 				   sizeof (struct mlx4_cmd_context),
@@ -389,11 +1029,10 @@ int mlx4_cmd_use_events(struct mlx4_dev *dev)
 		; /* nothing */
 	--priv->cmd.token_mask;
 
-	priv->cmd.use_events = 1;
-
 	down(&priv->cmd.poll_sem);
+	priv->cmd.use_events = 1;
 
-	return 0;
+	return err;
 }
 
 /*
@@ -433,7 +1072,8 @@ struct mlx4_cmd_mailbox *mlx4_alloc_cmd_mailbox(struct mlx4_dev *dev)
 }
 EXPORT_SYMBOL_GPL(mlx4_alloc_cmd_mailbox);
 
-void mlx4_free_cmd_mailbox(struct mlx4_dev *dev, struct mlx4_cmd_mailbox *mailbox)
+void mlx4_free_cmd_mailbox(struct mlx4_dev *dev,
+			   struct mlx4_cmd_mailbox *mailbox)
 {
 	if (!mailbox)
 		return;
@@ -442,3 +1082,8 @@ void mlx4_free_cmd_mailbox(struct mlx4_dev *dev, struct mlx4_cmd_mailbox *mailbo
 	kfree(mailbox);
 }
 EXPORT_SYMBOL_GPL(mlx4_free_cmd_mailbox);
+
+u32 mlx4_comm_get_version(void)
+{
+	 return ((u32) CMD_CHAN_IF_REV << 8) | (u32) CMD_CHAN_VER;
+}