IB/iser: Prevent invalidating wrong MR

The iser_reg_resources structure has two pointers to MR but only one
mr_valid field. The implementation assumes that we use only *sig_mr when
pi_enable is true. Otherwise, we use only *mr. However, it is only
sometimes correct. Read commands without protection information occur even
when pi_enble is true. For example, the following SCSI commands have a
Data-In buffer but never have protection information: READ CAPACITY (16),
INQUIRY, MODE SENSE(6), MAINTENANCE IN. So, we use
*sig_mr for some SCSI commands and *mr for the other SCSI commands.

In most cases, it works fine because the remote invalidation is applied.
However, there are two cases when the remote invalidation is not
applicable.
 1. Small write commands when all data is sent as an immediate.
 2. The target does not support the remote invalidation feature.

The lazy invalidation is used if the remote invalidation is impossible.
Since, at the lazy invalidation, we always invalidate the MR we want to
use, the wrong MR may be invalidated.

To fix the issue, we need a field per MR that indicates the MR needs
invalidation. Since the ib_mr structure already has such a field, let's
use ib_mr.need_inval instead of iser_reg_resources.mr_valid.

Fixes: b76a439 ("IB/iser: Use IB_WR_REG_MR_INTEGRITY for PI handover")
Link: https://lore.kernel.org/r/[email protected]
Acked-by: Max Gurtovoy <[email protected]>
Signed-off-by: Sergey Gorenko <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>

Author: SergeyGorenko

drivers/infiniband/ulp/iser/iscsi_iser.h

@@ -316,12 +316,10 @@ struct iser_device {
  *
  * @mr:         memory region
  * @sig_mr:     signature memory region
- * @mr_valid:   is mr valid indicator
  */
 struct iser_reg_resources {
 	struct ib_mr                     *mr;
 	struct ib_mr                     *sig_mr;
-	u8				  mr_valid:1;
 };
 
 /**

drivers/infiniband/ulp/iser/iser_initiator.c

@@ -581,7 +581,10 @@ static inline int iser_inv_desc(struct iser_fr_desc *desc, u32 rkey)
 		return -EINVAL;
 	}
 
-	desc->rsc.mr_valid = 0;
+	if (desc->sig_protected)
+		desc->rsc.sig_mr->need_inval = false;
+	else
+		desc->rsc.mr->need_inval = false;
 
 	return 0;
 }

drivers/infiniband/ulp/iser/iser_memory.c

@@ -264,7 +264,7 @@ static int iser_reg_sig_mr(struct iscsi_iser_task *iser_task,
 
 	iser_set_prot_checks(iser_task->sc, &sig_attrs->check_mask);
 
-	if (rsc->mr_valid)
+	if (rsc->sig_mr->need_inval)
 		iser_inv_rkey(&tx_desc->inv_wr, mr, cqe, &wr->wr);
 
 	ib_update_fast_reg_key(mr, ib_inc_rkey(mr->rkey));
@@ -288,7 +288,7 @@ static int iser_reg_sig_mr(struct iscsi_iser_task *iser_task,
 	wr->access = IB_ACCESS_LOCAL_WRITE |
 		     IB_ACCESS_REMOTE_READ |
 		     IB_ACCESS_REMOTE_WRITE;
-	rsc->mr_valid = 1;
+	rsc->sig_mr->need_inval = true;
 
 	sig_reg->sge.lkey = mr->lkey;
 	sig_reg->rkey = mr->rkey;
@@ -313,7 +313,7 @@ static int iser_fast_reg_mr(struct iscsi_iser_task *iser_task,
 	struct ib_reg_wr *wr = &tx_desc->reg_wr;
 	int n;
 
-	if (rsc->mr_valid)
+	if (rsc->mr->need_inval)
 		iser_inv_rkey(&tx_desc->inv_wr, mr, cqe, &wr->wr);
 
 	ib_update_fast_reg_key(mr, ib_inc_rkey(mr->rkey));
@@ -336,7 +336,7 @@ static int iser_fast_reg_mr(struct iscsi_iser_task *iser_task,
 		     IB_ACCESS_REMOTE_WRITE |
 		     IB_ACCESS_REMOTE_READ;
 
-	rsc->mr_valid = 1;
+	rsc->mr->need_inval = true;
 
 	reg->sge.lkey = mr->lkey;
 	reg->rkey = mr->rkey;

drivers/infiniband/ulp/iser/iser_verbs.c

@@ -129,7 +129,6 @@ iser_create_fastreg_desc(struct iser_device *device,
 			goto err_alloc_mr_integrity;
 		}
 	}
-	desc->rsc.mr_valid = 0;
 
 	return desc;