1 files changed, 220 insertions, 218 deletions

diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index dc5c35210c16..6821f225248b 100644
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -18,6 +18,7 @@
 #include <linux/uio.h>
 #include <linux/interrupt.h>
 #include <linux/set_memory.h>
+#include <linux/export.h>
 #include <asm/page.h>
 #include <asm/mshyperv.h>
 
@@ -153,7 +154,9 @@ void vmbus_free_ring(struct vmbus_channel *channel)
 	hv_ringbuffer_cleanup(&channel->inbound);
 
 	if (channel->ringbuffer_page) {
-		__free_pages(channel->ringbuffer_page,
+		/* In a CoCo VM leak the memory if it didn't get re-encrypted */
+		if (!channel->ringbuffer_gpadlhandle.decrypted)
+			__free_pages(channel->ringbuffer_page,
 			     get_order(channel->ringbuffer_pagecount
 				       << PAGE_SHIFT));
 		channel->ringbuffer_page = NULL;
@@ -322,125 +325,104 @@ static int create_gpadl_header(enum hv_gpadl_type type, void *kbuffer,
 
 	pagecount = hv_gpadl_size(type, size) >> HV_HYP_PAGE_SHIFT;
 
-	/* do we need a gpadl body msg */
 	pfnsize = MAX_SIZE_CHANNEL_MESSAGE -
 		  sizeof(struct vmbus_channel_gpadl_header) -
 		  sizeof(struct gpa_range);
+	pfncount = umin(pagecount, pfnsize / sizeof(u64));
+
+	msgsize = sizeof(struct vmbus_channel_msginfo) +
+		  sizeof(struct vmbus_channel_gpadl_header) +
+		  sizeof(struct gpa_range) + pfncount * sizeof(u64);
+	msgheader =  kzalloc(msgsize, GFP_KERNEL);
+	if (!msgheader)
+		return -ENOMEM;
+
+	INIT_LIST_HEAD(&msgheader->submsglist);
+	msgheader->msgsize = msgsize;
+
+	gpadl_header = (struct vmbus_channel_gpadl_header *)
+		msgheader->msg;
+	gpadl_header->rangecount = 1;
+	gpadl_header->range_buflen = sizeof(struct gpa_range) +
+				 pagecount * sizeof(u64);
+	gpadl_header->range[0].byte_offset = 0;
+	gpadl_header->range[0].byte_count = hv_gpadl_size(type, size);
+	for (i = 0; i < pfncount; i++)
+		gpadl_header->range[0].pfn_array[i] = hv_gpadl_hvpfn(
+			type, kbuffer, size, send_offset, i);
+	*msginfo = msgheader;
+
+	pfnsum = pfncount;
+	pfnleft = pagecount - pfncount;
+
+	/* how many pfns can we fit in a body message */
+	pfnsize = MAX_SIZE_CHANNEL_MESSAGE -
+		  sizeof(struct vmbus_channel_gpadl_body);
 	pfncount = pfnsize / sizeof(u64);
 
-	if (pagecount > pfncount) {
-		/* we need a gpadl body */
-		/* fill in the header */
+	/*
+	 * If pfnleft is zero, everything fits in the header and no body
+	 * messages are needed
+	 */
+	while (pfnleft) {
+		pfncurr = umin(pfncount, pfnleft);
 		msgsize = sizeof(struct vmbus_channel_msginfo) +
-			  sizeof(struct vmbus_channel_gpadl_header) +
-			  sizeof(struct gpa_range) + pfncount * sizeof(u64);
-		msgheader =  kzalloc(msgsize, GFP_KERNEL);
-		if (!msgheader)
-			goto nomem;
-
-		INIT_LIST_HEAD(&msgheader->submsglist);
-		msgheader->msgsize = msgsize;
-
-		gpadl_header = (struct vmbus_channel_gpadl_header *)
-			msgheader->msg;
-		gpadl_header->rangecount = 1;
-		gpadl_header->range_buflen = sizeof(struct gpa_range) +
-					 pagecount * sizeof(u64);
-		gpadl_header->range[0].byte_offset = 0;
-		gpadl_header->range[0].byte_count = hv_gpadl_size(type, size);
-		for (i = 0; i < pfncount; i++)
-			gpadl_header->range[0].pfn_array[i] = hv_gpadl_hvpfn(
-				type, kbuffer, size, send_offset, i);
-		*msginfo = msgheader;
-
-		pfnsum = pfncount;
-		pfnleft = pagecount - pfncount;
-
-		/* how many pfns can we fit */
-		pfnsize = MAX_SIZE_CHANNEL_MESSAGE -
-			  sizeof(struct vmbus_channel_gpadl_body);
-		pfncount = pfnsize / sizeof(u64);
-
-		/* fill in the body */
-		while (pfnleft) {
-			if (pfnleft > pfncount)
-				pfncurr = pfncount;
-			else
-				pfncurr = pfnleft;
-
-			msgsize = sizeof(struct vmbus_channel_msginfo) +
-				  sizeof(struct vmbus_channel_gpadl_body) +
-				  pfncurr * sizeof(u64);
-			msgbody = kzalloc(msgsize, GFP_KERNEL);
-
-			if (!msgbody) {
-				struct vmbus_channel_msginfo *pos = NULL;
-				struct vmbus_channel_msginfo *tmp = NULL;
-				/*
-				 * Free up all the allocated messages.
-				 */
-				list_for_each_entry_safe(pos, tmp,
-					&msgheader->submsglist,
-					msglistentry) {
-
-					list_del(&pos->msglistentry);
-					kfree(pos);
-				}
-
-				goto nomem;
-			}
-
-			msgbody->msgsize = msgsize;
-			gpadl_body =
-				(struct vmbus_channel_gpadl_body *)msgbody->msg;
+			  sizeof(struct vmbus_channel_gpadl_body) +
+			  pfncurr * sizeof(u64);
+		msgbody = kzalloc(msgsize, GFP_KERNEL);
 
+		if (!msgbody) {
+			struct vmbus_channel_msginfo *pos = NULL;
+			struct vmbus_channel_msginfo *tmp = NULL;
 			/*
-			 * Gpadl is u32 and we are using a pointer which could
-			 * be 64-bit
-			 * This is governed by the guest/host protocol and
-			 * so the hypervisor guarantees that this is ok.
+			 * Free up all the allocated messages.
 			 */
-			for (i = 0; i < pfncurr; i++)
-				gpadl_body->pfn[i] = hv_gpadl_hvpfn(type,
-					kbuffer, size, send_offset, pfnsum + i);
-
-			/* add to msg header */
-			list_add_tail(&msgbody->msglistentry,
-				      &msgheader->submsglist);
-			pfnsum += pfncurr;
-			pfnleft -= pfncurr;
+			list_for_each_entry_safe(pos, tmp,
+				&msgheader->submsglist,
+				msglistentry) {
+
+				list_del(&pos->msglistentry);
+				kfree(pos);
+			}
+			kfree(msgheader);
+			return -ENOMEM;
 		}
-	} else {
-		/* everything fits in a header */
-		msgsize = sizeof(struct vmbus_channel_msginfo) +
-			  sizeof(struct vmbus_channel_gpadl_header) +
-			  sizeof(struct gpa_range) + pagecount * sizeof(u64);
-		msgheader = kzalloc(msgsize, GFP_KERNEL);
-		if (msgheader == NULL)
-			goto nomem;
-
-		INIT_LIST_HEAD(&msgheader->submsglist);
-		msgheader->msgsize = msgsize;
-
-		gpadl_header = (struct vmbus_channel_gpadl_header *)
-			msgheader->msg;
-		gpadl_header->rangecount = 1;
-		gpadl_header->range_buflen = sizeof(struct gpa_range) +
-					 pagecount * sizeof(u64);
-		gpadl_header->range[0].byte_offset = 0;
-		gpadl_header->range[0].byte_count = hv_gpadl_size(type, size);
-		for (i = 0; i < pagecount; i++)
-			gpadl_header->range[0].pfn_array[i] = hv_gpadl_hvpfn(
-				type, kbuffer, size, send_offset, i);
-
-		*msginfo = msgheader;
+
+		msgbody->msgsize = msgsize;
+		gpadl_body = (struct vmbus_channel_gpadl_body *)msgbody->msg;
+
+		/*
+		 * Gpadl is u32 and we are using a pointer which could
+		 * be 64-bit
+		 * This is governed by the guest/host protocol and
+		 * so the hypervisor guarantees that this is ok.
+		 */
+		for (i = 0; i < pfncurr; i++)
+			gpadl_body->pfn[i] = hv_gpadl_hvpfn(type,
+				kbuffer, size, send_offset, pfnsum + i);
+
+		/* add to msg header */
+		list_add_tail(&msgbody->msglistentry, &msgheader->submsglist);
+		pfnsum += pfncurr;
+		pfnleft -= pfncurr;
 	}
 
 	return 0;
-nomem:
-	kfree(msgheader);
-	kfree(msgbody);
-	return -ENOMEM;
+}
+
+static void vmbus_free_channel_msginfo(struct vmbus_channel_msginfo *msginfo)
+{
+	struct vmbus_channel_msginfo *submsginfo, *tmp;
+
+	if (!msginfo)
+		return;
+
+	list_for_each_entry_safe(submsginfo, tmp, &msginfo->submsglist,
+				 msglistentry) {
+		kfree(submsginfo);
+	}
+
+	kfree(msginfo);
 }
 
 /*
@@ -462,7 +444,7 @@ static int __vmbus_establish_gpadl(struct vmbus_channel *channel,
 	struct vmbus_channel_gpadl_header *gpadlmsg;
 	struct vmbus_channel_gpadl_body *gpadl_body;
 	struct vmbus_channel_msginfo *msginfo = NULL;
-	struct vmbus_channel_msginfo *submsginfo, *tmp;
+	struct vmbus_channel_msginfo *submsginfo;
 	struct list_head *curr;
 	u32 next_gpadl_handle;
 	unsigned long flags;
@@ -472,18 +454,31 @@ static int __vmbus_establish_gpadl(struct vmbus_channel *channel,
 		(atomic_inc_return(&vmbus_connection.next_gpadl_handle) - 1);
 
 	ret = create_gpadl_header(type, kbuffer, size, send_offset, &msginfo);
-	if (ret)
-		return ret;
-
-	ret = set_memory_decrypted((unsigned long)kbuffer,
-				   PFN_UP(size));
 	if (ret) {
-		dev_warn(&channel->device_obj->device,
-			 "Failed to set host visibility for new GPADL %d.\n",
-			 ret);
+		gpadl->decrypted = false;
 		return ret;
 	}
 
+	gpadl->decrypted = !((channel->co_external_memory && type == HV_GPADL_BUFFER) ||
+		(channel->co_ring_buffer && type == HV_GPADL_RING));
+	if (gpadl->decrypted) {
+		/*
+		 * The "decrypted" flag being true assumes that set_memory_decrypted() succeeds.
+		 * But if it fails, the encryption state of the memory is unknown. In that case,
+		 * leave "decrypted" as true to ensure the memory is leaked instead of going back
+		 * on the free list.
+		 */
+		ret = set_memory_decrypted((unsigned long)kbuffer,
+					PFN_UP(size));
+		if (ret) {
+			dev_warn(&channel->device_obj->device,
+				"Failed to set host visibility for new GPADL %d.\n",
+				ret);
+			vmbus_free_channel_msginfo(msginfo);
+			return ret;
+		}
+	}
+
 	init_completion(&msginfo->waitevent);
 	msginfo->waiting_channel = channel;
 
@@ -556,16 +551,20 @@ cleanup:
 	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
 	list_del(&msginfo->msglistentry);
 	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
-	list_for_each_entry_safe(submsginfo, tmp, &msginfo->submsglist,
-				 msglistentry) {
-		kfree(submsginfo);
-	}
 
-	kfree(msginfo);
+	vmbus_free_channel_msginfo(msginfo);
 
-	if (ret)
-		set_memory_encrypted((unsigned long)kbuffer,
-				     PFN_UP(size));
+	if (ret) {
+		/*
+		 * If set_memory_encrypted() fails, the decrypted flag is
+		 * left as true so the memory is leaked instead of being
+		 * put back on the free list.
+		 */
+		if (gpadl->decrypted) {
+			if (!set_memory_encrypted((unsigned long)kbuffer, PFN_UP(size)))
+				gpadl->decrypted = false;
+		}
+	}
 
 	return ret;
 }
@@ -591,7 +590,7 @@ EXPORT_SYMBOL_GPL(vmbus_establish_gpadl);
  * keeps track of the next available slot in the array. Initially, each
  * slot points to the next one (as in a Linked List). The last slot
  * does not point to anything, so its value is U64_MAX by default.
- * @size The size of the array
+ * @size: The size of the array
  */
 static u64 *request_arr_init(u32 size)
 {
@@ -695,12 +694,13 @@ static int __vmbus_open(struct vmbus_channel *newchannel,
 		goto error_clean_ring;
 
 	err = hv_ringbuffer_init(&newchannel->outbound,
-				 page, send_pages, 0);
+				 page, send_pages, 0, newchannel->co_ring_buffer);
 	if (err)
 		goto error_free_gpadl;
 
 	err = hv_ringbuffer_init(&newchannel->inbound, &page[send_pages],
-				 recv_pages, newchannel->max_pkt_size);
+				 recv_pages, newchannel->max_pkt_size,
+				 newchannel->co_ring_buffer);
 	if (err)
 		goto error_free_gpadl;
 
@@ -881,11 +881,16 @@ post_msg_err:
 
 	kfree(info);
 
-	ret = set_memory_encrypted((unsigned long)gpadl->buffer,
-				   PFN_UP(gpadl->size));
+	if (gpadl->decrypted)
+		ret = set_memory_encrypted((unsigned long)gpadl->buffer,
+					PFN_UP(gpadl->size));
+	else
+		ret = 0;
 	if (ret)
 		pr_warn("Fail to set mem host visibility in GPADL teardown %d.\n", ret);
 
+	gpadl->decrypted = ret;
+
 	return ret;
 }
 EXPORT_SYMBOL_GPL(vmbus_teardown_gpadl);
@@ -941,7 +946,7 @@ static int vmbus_close_internal(struct vmbus_channel *channel)
 
 	/* Send a closing message */
 
-	msg = &channel->close_msg.msg;
+	msg = &channel->close_msg;
 
 	msg->header.msgtype = CHANNELMSG_CLOSECHANNEL;
 	msg->child_relid = channel->offermsg.child_relid;
@@ -1022,11 +1027,13 @@ void vmbus_close(struct vmbus_channel *channel)
 EXPORT_SYMBOL_GPL(vmbus_close);
 
 /**
- * vmbus_sendpacket() - Send the specified buffer on the given channel
+ * vmbus_sendpacket_getid() - Send the specified buffer on the given channel
  * @channel: Pointer to vmbus_channel structure
  * @buffer: Pointer to the buffer you want to send the data from.
  * @bufferlen: Maximum size of what the buffer holds.
  * @requestid: Identifier of the request
+ * @trans_id: Identifier of the transaction associated to this request, if
+ *            the send is successful; undefined, otherwise.
  * @type: Type of packet that is being sent e.g. negotiate, time
  *	  packet etc.
  * @flags: 0 or VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED
@@ -1036,8 +1043,8 @@ EXPORT_SYMBOL_GPL(vmbus_close);
  *
  * Mainly used by Hyper-V drivers.
  */
-int vmbus_sendpacket(struct vmbus_channel *channel, void *buffer,
-			   u32 bufferlen, u64 requestid,
+int vmbus_sendpacket_getid(struct vmbus_channel *channel, void *buffer,
+			   u32 bufferlen, u64 requestid, u64 *trans_id,
 			   enum vmbus_packet_type type, u32 flags)
 {
 	struct vmpacket_descriptor desc;
@@ -1063,73 +1070,39 @@ int vmbus_sendpacket(struct vmbus_channel *channel, void *buffer,
 	bufferlist[2].iov_base = &aligned_data;
 	bufferlist[2].iov_len = (packetlen_aligned - packetlen);
 
-	return hv_ringbuffer_write(channel, bufferlist, num_vecs, requestid);
+	return hv_ringbuffer_write(channel, bufferlist, num_vecs, requestid, trans_id);
 }
-EXPORT_SYMBOL(vmbus_sendpacket);
+EXPORT_SYMBOL(vmbus_sendpacket_getid);
 
-/*
- * vmbus_sendpacket_pagebuffer - Send a range of single-page buffer
- * packets using a GPADL Direct packet type. This interface allows you
- * to control notifying the host. This will be useful for sending
- * batched data. Also the sender can control the send flags
- * explicitly.
+/**
+ * vmbus_sendpacket() - Send the specified buffer on the given channel
+ * @channel: Pointer to vmbus_channel structure
+ * @buffer: Pointer to the buffer you want to send the data from.
+ * @bufferlen: Maximum size of what the buffer holds.
+ * @requestid: Identifier of the request
+ * @type: Type of packet that is being sent e.g. negotiate, time
+ *	  packet etc.
+ * @flags: 0 or VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED
+ *
+ * Sends data in @buffer directly to Hyper-V via the vmbus.
+ * This will send the data unparsed to Hyper-V.
+ *
+ * Mainly used by Hyper-V drivers.
  */
-int vmbus_sendpacket_pagebuffer(struct vmbus_channel *channel,
-				struct hv_page_buffer pagebuffers[],
-				u32 pagecount, void *buffer, u32 bufferlen,
-				u64 requestid)
+int vmbus_sendpacket(struct vmbus_channel *channel, void *buffer,
+		     u32 bufferlen, u64 requestid,
+		     enum vmbus_packet_type type, u32 flags)
 {
-	int i;
-	struct vmbus_channel_packet_page_buffer desc;
-	u32 descsize;
-	u32 packetlen;
-	u32 packetlen_aligned;
-	struct kvec bufferlist[3];
-	u64 aligned_data = 0;
-
-	if (pagecount > MAX_PAGE_BUFFER_COUNT)
-		return -EINVAL;
-
-	/*
-	 * Adjust the size down since vmbus_channel_packet_page_buffer is the
-	 * largest size we support
-	 */
-	descsize = sizeof(struct vmbus_channel_packet_page_buffer) -
-			  ((MAX_PAGE_BUFFER_COUNT - pagecount) *
-			  sizeof(struct hv_page_buffer));
-	packetlen = descsize + bufferlen;
-	packetlen_aligned = ALIGN(packetlen, sizeof(u64));
-
-	/* Setup the descriptor */
-	desc.type = VM_PKT_DATA_USING_GPA_DIRECT;
-	desc.flags = VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED;
-	desc.dataoffset8 = descsize >> 3; /* in 8-bytes granularity */
-	desc.length8 = (u16)(packetlen_aligned >> 3);
-	desc.transactionid = VMBUS_RQST_ERROR; /* will be updated in hv_ringbuffer_write() */
-	desc.reserved = 0;
-	desc.rangecount = pagecount;
-
-	for (i = 0; i < pagecount; i++) {
-		desc.range[i].len = pagebuffers[i].len;
-		desc.range[i].offset = pagebuffers[i].offset;
-		desc.range[i].pfn	 = pagebuffers[i].pfn;
-	}
-
-	bufferlist[0].iov_base = &desc;
-	bufferlist[0].iov_len = descsize;
-	bufferlist[1].iov_base = buffer;
-	bufferlist[1].iov_len = bufferlen;
-	bufferlist[2].iov_base = &aligned_data;
-	bufferlist[2].iov_len = (packetlen_aligned - packetlen);
-
-	return hv_ringbuffer_write(channel, bufferlist, 3, requestid);
+	return vmbus_sendpacket_getid(channel, buffer, bufferlen,
+				      requestid, NULL, type, flags);
 }
-EXPORT_SYMBOL_GPL(vmbus_sendpacket_pagebuffer);
+EXPORT_SYMBOL(vmbus_sendpacket);
 
 /*
- * 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,
@@ -1151,7 +1124,6 @@ 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;
@@ -1160,7 +1132,7 @@ int vmbus_sendpacket_mpb_desc(struct vmbus_channel *channel,
 	bufferlist[2].iov_base = &aligned_data;
 	bufferlist[2].iov_len = (packetlen_aligned - packetlen);
 
-	return hv_ringbuffer_write(channel, bufferlist, 3, requestid);
+	return hv_ringbuffer_write(channel, bufferlist, 3, requestid, NULL);
 }
 EXPORT_SYMBOL_GPL(vmbus_sendpacket_mpb_desc);
 
@@ -1226,12 +1198,12 @@ u64 vmbus_next_request_id(struct vmbus_channel *channel, u64 rqst_addr)
 	if (!channel->rqstor_size)
 		return VMBUS_NO_RQSTOR;
 
-	spin_lock_irqsave(&rqstor->req_lock, flags);
+	lock_requestor(channel, flags);
 	current_id = rqstor->next_request_id;
 
 	/* Requestor array is full */
 	if (current_id >= rqstor->size) {
-		spin_unlock_irqrestore(&rqstor->req_lock, flags);
+		unlock_requestor(channel, flags);
 		return VMBUS_RQST_ERROR;
 	}
 
@@ -1241,27 +1213,23 @@ u64 vmbus_next_request_id(struct vmbus_channel *channel, u64 rqst_addr)
 	/* The already held spin lock provides atomicity */
 	bitmap_set(rqstor->req_bitmap, current_id, 1);
 
-	spin_unlock_irqrestore(&rqstor->req_lock, flags);
+	unlock_requestor(channel, flags);
 
 	/*
 	 * Cannot return an ID of 0, which is reserved for an unsolicited
-	 * message from Hyper-V.
+	 * message from Hyper-V; Hyper-V does not acknowledge (respond to)
+	 * VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED requests with ID of
+	 * 0 sent by the guest.
 	 */
 	return current_id + 1;
 }
 EXPORT_SYMBOL_GPL(vmbus_next_request_id);
 
-/*
- * vmbus_request_addr - Returns the memory address stored at @trans_id
- * in @rqstor. Uses a spin lock to avoid race conditions.
- * @channel: Pointer to the VMbus channel struct
- * @trans_id: Request id sent back from Hyper-V. Becomes the requestor's
- * next request id.
- */
-u64 vmbus_request_addr(struct vmbus_channel *channel, u64 trans_id)
+/* As in vmbus_request_addr_match() but without the requestor lock */
+u64 __vmbus_request_addr_match(struct vmbus_channel *channel, u64 trans_id,
+			       u64 rqst_addr)
 {
 	struct vmbus_requestor *rqstor = &channel->requestor;
-	unsigned long flags;
 	u64 req_addr;
 
 	/* Check rqstor has been initialized */
@@ -1270,27 +1238,61 @@ u64 vmbus_request_addr(struct vmbus_channel *channel, u64 trans_id)
 
 	/* Hyper-V can send an unsolicited message with ID of 0 */
 	if (!trans_id)
-		return trans_id;
-
-	spin_lock_irqsave(&rqstor->req_lock, flags);
+		return VMBUS_RQST_ERROR;
 
 	/* Data corresponding to trans_id is stored at trans_id - 1 */
 	trans_id--;
 
 	/* Invalid trans_id */
-	if (trans_id >= rqstor->size || !test_bit(trans_id, rqstor->req_bitmap)) {
-		spin_unlock_irqrestore(&rqstor->req_lock, flags);
+	if (trans_id >= rqstor->size || !test_bit(trans_id, rqstor->req_bitmap))
 		return VMBUS_RQST_ERROR;
-	}
 
 	req_addr = rqstor->req_arr[trans_id];
-	rqstor->req_arr[trans_id] = rqstor->next_request_id;
-	rqstor->next_request_id = trans_id;
+	if (rqst_addr == VMBUS_RQST_ADDR_ANY || req_addr == rqst_addr) {
+		rqstor->req_arr[trans_id] = rqstor->next_request_id;
+		rqstor->next_request_id = trans_id;
 
-	/* The already held spin lock provides atomicity */
-	bitmap_clear(rqstor->req_bitmap, trans_id, 1);
+		/* The already held spin lock provides atomicity */
+		bitmap_clear(rqstor->req_bitmap, trans_id, 1);
+	}
+
+	return req_addr;
+}
+EXPORT_SYMBOL_GPL(__vmbus_request_addr_match);
+
+/*
+ * vmbus_request_addr_match - Clears/removes @trans_id from the @channel's
+ * requestor, provided the memory address stored at @trans_id equals @rqst_addr
+ * (or provided @rqst_addr matches the sentinel value VMBUS_RQST_ADDR_ANY).
+ *
+ * Returns the memory address stored at @trans_id, or VMBUS_RQST_ERROR if
+ * @trans_id is not contained in the requestor.
+ *
+ * Acquires and releases the requestor spin lock.
+ */
+u64 vmbus_request_addr_match(struct vmbus_channel *channel, u64 trans_id,
+			     u64 rqst_addr)
+{
+	unsigned long flags;
+	u64 req_addr;
+
+	lock_requestor(channel, flags);
+	req_addr = __vmbus_request_addr_match(channel, trans_id, rqst_addr);
+	unlock_requestor(channel, flags);
 
-	spin_unlock_irqrestore(&rqstor->req_lock, flags);
 	return req_addr;
 }
+EXPORT_SYMBOL_GPL(vmbus_request_addr_match);
+
+/*
+ * vmbus_request_addr - Returns the memory address stored at @trans_id
+ * in @rqstor. Uses a spin lock to avoid race conditions.
+ * @channel: Pointer to the VMbus channel struct
+ * @trans_id: Request id sent back from Hyper-V. Becomes the requestor's
+ * next request id.
+ */
+u64 vmbus_request_addr(struct vmbus_channel *channel, u64 trans_id)
+{
+	return vmbus_request_addr_match(channel, trans_id, VMBUS_RQST_ADDR_ANY);
+}
 EXPORT_SYMBOL_GPL(vmbus_request_addr);