Drivers: hv: Allow vmbus_sendpacket_mpb_desc() to create multiple ranges

vmbus_sendpacket_mpb_desc() is currently used only by the storvsc driver
and is hardcoded to create a single GPA range. To allow it to also be
used by the netvsc driver to create multiple GPA ranges, no longer
hardcode as having a single GPA range. Allow the calling driver to
specify the rangecount in the supplied descriptor.

Update the storvsc driver to reflect this new approach.

Cc: <stable@vger.kernel.org> # 6.1.x
Signed-off-by: Michael Kelley <mhklinux@outlook.com>
Link: https://patch.msgid.link/20250513000604.1396-2-mhklinux@outlook.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: mhklinux

drivers/hv/channel.c

@@ -1136,9 +1136,10 @@ int vmbus_sendpacket_pagebuffer(struct vmbus_channel *channel,
 EXPORT_SYMBOL_GPL(vmbus_sendpacket_pagebuffer);
 
 /*
- * vmbus_sendpacket_multipagebuffer - Send a multi-page buffer packet
+ * vmbus_sendpacket_mpb_desc - Send one or more multi-page buffer packets
  * using a GPADL Direct packet type.
- * The buffer includes the vmbus descriptor.
+ * The desc argument must include space for the VMBus descriptor. The
+ * rangecount field must already be set.
  */
 int vmbus_sendpacket_mpb_desc(struct vmbus_channel *channel,
 			      struct vmbus_packet_mpb_array *desc,
@@ -1160,7 +1161,6 @@ int vmbus_sendpacket_mpb_desc(struct vmbus_channel *channel,
 	desc->length8 = (u16)(packetlen_aligned >> 3);
 	desc->transactionid = VMBUS_RQST_ERROR; /* will be updated in hv_ringbuffer_write() */
 	desc->reserved = 0;
-	desc->rangecount = 1;
 
 	bufferlist[0].iov_base = desc;
 	bufferlist[0].iov_len = desc_size;

drivers/scsi/storvsc_drv.c

@@ -1819,6 +1819,7 @@ static int storvsc_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *scmnd)
 				return SCSI_MLQUEUE_DEVICE_BUSY;
 		}
 
+		payload->rangecount = 1;
 		payload->range.len = length;
 		payload->range.offset = offset_in_hvpg;