RDMA/qedr: Add EDPM max size to alloc ucontext response

User space should receive the maximum edpm size from kernel driver,
similar to other edpm/ldpm related limits.  Add an additional parameter to
the alloc_ucontext_resp structure for the edpm maximum size.

In addition, pass an indication from user-space to kernel
(and not just kernel to user) that the DPM sizes are supported.

This is for supporting backward-forward compatibility between driver and
lib for everything related to DPM transaction and limit sizes.

This should have been part of commit mentioned in Fixes tag.

Link: https://lore.kernel.org/r/20200707063100.3811-3-michal.kalderon@marvell.com
Fixes: 93a3d05f ("RDMA/qedr: Add kernel capability flags for dpm enabled mode")
Signed-off-by: Ariel Elior <ariel.elior@marvell.com>
Signed-off-by: Michal Kalderon <michal.kalderon@marvell.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

drivers/infiniband/hw/qedr/verbs.c

@@ -320,9 +320,12 @@ int qedr_alloc_ucontext(struct ib_ucontext *uctx, struct ib_udata *udata)
 				  QEDR_DPM_TYPE_ROCE_LEGACY |
 				  QEDR_DPM_TYPE_ROCE_EDPM_MODE;
 
-	uresp.dpm_flags |= QEDR_DPM_SIZES_SET;
-	uresp.ldpm_limit_size = QEDR_LDPM_MAX_SIZE;
-	uresp.edpm_trans_size = QEDR_EDPM_TRANS_SIZE;
+	if (ureq.context_flags & QEDR_SUPPORT_DPM_SIZES) {
+		uresp.dpm_flags |= QEDR_DPM_SIZES_SET;
+		uresp.ldpm_limit_size = QEDR_LDPM_MAX_SIZE;
+		uresp.edpm_trans_size = QEDR_EDPM_TRANS_SIZE;
+		uresp.edpm_limit_size = QEDR_EDPM_MAX_SIZE;
+	}
 
 	uresp.wids_enabled = 1;
 	uresp.wid_count = oparams.wid_count;

include/uapi/rdma/qedr-abi.h

@@ -40,7 +40,8 @@
 /* user kernel communication data structures. */
 enum qedr_alloc_ucontext_flags {
 	QEDR_ALLOC_UCTX_EDPM_MODE	= 1 << 0,
-	QEDR_ALLOC_UCTX_DB_REC		= 1 << 1
+	QEDR_ALLOC_UCTX_DB_REC		= 1 << 1,
+	QEDR_SUPPORT_DPM_SIZES		= 1 << 2,
 };
 
 struct qedr_alloc_ucontext_req {
@@ -50,6 +51,7 @@ struct qedr_alloc_ucontext_req {
 
 #define QEDR_LDPM_MAX_SIZE	(8192)
 #define QEDR_EDPM_TRANS_SIZE	(64)
+#define QEDR_EDPM_MAX_SIZE	(ROCE_REQ_MAX_INLINE_DATA_SIZE)
 
 enum qedr_rdma_dpm_type {
 	QEDR_DPM_TYPE_NONE		= 0,
@@ -77,6 +79,8 @@ struct qedr_alloc_ucontext_resp {
 	__u16 ldpm_limit_size;
 	__u8 edpm_trans_size;
 	__u8 reserved;
+	__u16 edpm_limit_size;
+	__u8 padding[6];
 };
 
 struct qedr_alloc_pd_ureq {