6 files changed, 357 insertions, 204 deletions

diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index 3ebda7707e46..fbdda9938039 100644
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -22,20 +22,97 @@
 
 #include "hyperv_vmbus.h"
 
-#define NUM_PAGES_SPANNED(addr, len) \
-((PAGE_ALIGN(addr + len) >> PAGE_SHIFT) - (addr >> PAGE_SHIFT))
+/*
+ * hv_gpadl_size - Return the real size of a gpadl, the size that Hyper-V uses
+ *
+ * For BUFFER gpadl, Hyper-V uses the exact same size as the guest does.
+ *
+ * For RING gpadl, in each ring, the guest uses one PAGE_SIZE as the header
+ * (because of the alignment requirement), however, the hypervisor only
+ * uses the first HV_HYP_PAGE_SIZE as the header, therefore leaving a
+ * (PAGE_SIZE - HV_HYP_PAGE_SIZE) gap. And since there are two rings in a
+ * ringbuffer, the total size for a RING gpadl that Hyper-V uses is the
+ * total size that the guest uses minus twice of the gap size.
+ */
+static inline u32 hv_gpadl_size(enum hv_gpadl_type type, u32 size)
+{
+	switch (type) {
+	case HV_GPADL_BUFFER:
+		return size;
+	case HV_GPADL_RING:
+		/* The size of a ringbuffer must be page-aligned */
+		BUG_ON(size % PAGE_SIZE);
+		/*
+		 * Two things to notice here:
+		 * 1) We're processing two ring buffers as a unit
+		 * 2) We're skipping any space larger than HV_HYP_PAGE_SIZE in
+		 * the first guest-size page of each of the two ring buffers.
+		 * So we effectively subtract out two guest-size pages, and add
+		 * back two Hyper-V size pages.
+		 */
+		return size - 2 * (PAGE_SIZE - HV_HYP_PAGE_SIZE);
+	}
+	BUG();
+	return 0;
+}
 
-static unsigned long virt_to_hvpfn(void *addr)
+/*
+ * hv_ring_gpadl_send_hvpgoffset - Calculate the send offset (in unit of
+ *                                 HV_HYP_PAGE) in a ring gpadl based on the
+ *                                 offset in the guest
+ *
+ * @offset: the offset (in bytes) where the send ringbuffer starts in the
+ *               virtual address space of the guest
+ */
+static inline u32 hv_ring_gpadl_send_hvpgoffset(u32 offset)
 {
-	phys_addr_t paddr;
 
-	if (is_vmalloc_addr(addr))
-		paddr = page_to_phys(vmalloc_to_page(addr)) +
-					 offset_in_page(addr);
-	else
-		paddr = __pa(addr);
+	/*
+	 * For RING gpadl, in each ring, the guest uses one PAGE_SIZE as the
+	 * header (because of the alignment requirement), however, the
+	 * hypervisor only uses the first HV_HYP_PAGE_SIZE as the header,
+	 * therefore leaving a (PAGE_SIZE - HV_HYP_PAGE_SIZE) gap.
+	 *
+	 * And to calculate the effective send offset in gpadl, we need to
+	 * substract this gap.
+	 */
+	return (offset - (PAGE_SIZE - HV_HYP_PAGE_SIZE)) >> HV_HYP_PAGE_SHIFT;
+}
 
-	return  paddr >> PAGE_SHIFT;
+/*
+ * hv_gpadl_hvpfn - Return the Hyper-V page PFN of the @i th Hyper-V page in
+ *                  the gpadl
+ *
+ * @type: the type of the gpadl
+ * @kbuffer: the pointer to the gpadl in the guest
+ * @size: the total size (in bytes) of the gpadl
+ * @send_offset: the offset (in bytes) where the send ringbuffer starts in the
+ *               virtual address space of the guest
+ * @i: the index
+ */
+static inline u64 hv_gpadl_hvpfn(enum hv_gpadl_type type, void *kbuffer,
+				 u32 size, u32 send_offset, int i)
+{
+	int send_idx = hv_ring_gpadl_send_hvpgoffset(send_offset);
+	unsigned long delta = 0UL;
+
+	switch (type) {
+	case HV_GPADL_BUFFER:
+		break;
+	case HV_GPADL_RING:
+		if (i == 0)
+			delta = 0;
+		else if (i <= send_idx)
+			delta = PAGE_SIZE - HV_HYP_PAGE_SIZE;
+		else
+			delta = 2 * (PAGE_SIZE - HV_HYP_PAGE_SIZE);
+		break;
+	default:
+		BUG();
+		break;
+	}
+
+	return virt_to_hvpfn(kbuffer + delta + (HV_HYP_PAGE_SIZE * i));
 }
 
 /*
@@ -112,160 +189,6 @@ int vmbus_alloc_ring(struct vmbus_channel *newchannel,
 }
 EXPORT_SYMBOL_GPL(vmbus_alloc_ring);
 
-static int __vmbus_open(struct vmbus_channel *newchannel,
-		       void *userdata, u32 userdatalen,
-		       void (*onchannelcallback)(void *context), void *context)
-{
-	struct vmbus_channel_open_channel *open_msg;
-	struct vmbus_channel_msginfo *open_info = NULL;
-	struct page *page = newchannel->ringbuffer_page;
-	u32 send_pages, recv_pages;
-	unsigned long flags;
-	int err;
-
-	if (userdatalen > MAX_USER_DEFINED_BYTES)
-		return -EINVAL;
-
-	send_pages = newchannel->ringbuffer_send_offset;
-	recv_pages = newchannel->ringbuffer_pagecount - send_pages;
-
-	if (newchannel->state != CHANNEL_OPEN_STATE)
-		return -EINVAL;
-
-	newchannel->state = CHANNEL_OPENING_STATE;
-	newchannel->onchannel_callback = onchannelcallback;
-	newchannel->channel_callback_context = context;
-
-	err = hv_ringbuffer_init(&newchannel->outbound, page, send_pages);
-	if (err)
-		goto error_clean_ring;
-
-	err = hv_ringbuffer_init(&newchannel->inbound,
-				 &page[send_pages], recv_pages);
-	if (err)
-		goto error_clean_ring;
-
-	/* Establish the gpadl for the ring buffer */
-	newchannel->ringbuffer_gpadlhandle = 0;
-
-	err = vmbus_establish_gpadl(newchannel,
-				    page_address(newchannel->ringbuffer_page),
-				    (send_pages + recv_pages) << PAGE_SHIFT,
-				    &newchannel->ringbuffer_gpadlhandle);
-	if (err)
-		goto error_clean_ring;
-
-	/* Create and init the channel open message */
-	open_info = kmalloc(sizeof(*open_info) +
-			   sizeof(struct vmbus_channel_open_channel),
-			   GFP_KERNEL);
-	if (!open_info) {
-		err = -ENOMEM;
-		goto error_free_gpadl;
-	}
-
-	init_completion(&open_info->waitevent);
-	open_info->waiting_channel = newchannel;
-
-	open_msg = (struct vmbus_channel_open_channel *)open_info->msg;
-	open_msg->header.msgtype = CHANNELMSG_OPENCHANNEL;
-	open_msg->openid = newchannel->offermsg.child_relid;
-	open_msg->child_relid = newchannel->offermsg.child_relid;
-	open_msg->ringbuffer_gpadlhandle = newchannel->ringbuffer_gpadlhandle;
-	open_msg->downstream_ringbuffer_pageoffset = newchannel->ringbuffer_send_offset;
-	open_msg->target_vp = hv_cpu_number_to_vp_number(newchannel->target_cpu);
-
-	if (userdatalen)
-		memcpy(open_msg->userdata, userdata, userdatalen);
-
-	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
-	list_add_tail(&open_info->msglistentry,
-		      &vmbus_connection.chn_msg_list);
-	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
-
-	if (newchannel->rescind) {
-		err = -ENODEV;
-		goto error_free_info;
-	}
-
-	err = vmbus_post_msg(open_msg,
-			     sizeof(struct vmbus_channel_open_channel), true);
-
-	trace_vmbus_open(open_msg, err);
-
-	if (err != 0)
-		goto error_clean_msglist;
-
-	wait_for_completion(&open_info->waitevent);
-
-	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
-	list_del(&open_info->msglistentry);
-	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
-
-	if (newchannel->rescind) {
-		err = -ENODEV;
-		goto error_free_info;
-	}
-
-	if (open_info->response.open_result.status) {
-		err = -EAGAIN;
-		goto error_free_info;
-	}
-
-	newchannel->state = CHANNEL_OPENED_STATE;
-	kfree(open_info);
-	return 0;
-
-error_clean_msglist:
-	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
-	list_del(&open_info->msglistentry);
-	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
-error_free_info:
-	kfree(open_info);
-error_free_gpadl:
-	vmbus_teardown_gpadl(newchannel, newchannel->ringbuffer_gpadlhandle);
-	newchannel->ringbuffer_gpadlhandle = 0;
-error_clean_ring:
-	hv_ringbuffer_cleanup(&newchannel->outbound);
-	hv_ringbuffer_cleanup(&newchannel->inbound);
-	newchannel->state = CHANNEL_OPEN_STATE;
-	return err;
-}
-
-/*
- * vmbus_connect_ring - Open the channel but reuse ring buffer
- */
-int vmbus_connect_ring(struct vmbus_channel *newchannel,
-		       void (*onchannelcallback)(void *context), void *context)
-{
-	return  __vmbus_open(newchannel, NULL, 0, onchannelcallback, context);
-}
-EXPORT_SYMBOL_GPL(vmbus_connect_ring);
-
-/*
- * vmbus_open - Open the specified channel.
- */
-int vmbus_open(struct vmbus_channel *newchannel,
-	       u32 send_ringbuffer_size, u32 recv_ringbuffer_size,
-	       void *userdata, u32 userdatalen,
-	       void (*onchannelcallback)(void *context), void *context)
-{
-	int err;
-
-	err = vmbus_alloc_ring(newchannel, send_ringbuffer_size,
-			       recv_ringbuffer_size);
-	if (err)
-		return err;
-
-	err = __vmbus_open(newchannel, userdata, userdatalen,
-			   onchannelcallback, context);
-	if (err)
-		vmbus_free_ring(newchannel);
-
-	return err;
-}
-EXPORT_SYMBOL_GPL(vmbus_open);
-
 /* Used for Hyper-V Socket: a guest client's connect() to the host */
 int vmbus_send_tl_connect_request(const guid_t *shv_guest_servie_id,
 				  const guid_t *shv_host_servie_id)
@@ -317,7 +240,8 @@ EXPORT_SYMBOL_GPL(vmbus_send_modifychannel);
 /*
  * create_gpadl_header - Creates a gpadl for the specified buffer
  */
-static int create_gpadl_header(void *kbuffer, u32 size,
+static int create_gpadl_header(enum hv_gpadl_type type, void *kbuffer,
+			       u32 size, u32 send_offset,
 			       struct vmbus_channel_msginfo **msginfo)
 {
 	int i;
@@ -330,7 +254,7 @@ static int create_gpadl_header(void *kbuffer, u32 size,
 
 	int pfnsum, pfncount, pfnleft, pfncurr, pfnsize;
 
-	pagecount = size >> PAGE_SHIFT;
+	pagecount = hv_gpadl_size(type, size) >> HV_HYP_PAGE_SHIFT;
 
 	/* do we need a gpadl body msg */
 	pfnsize = MAX_SIZE_CHANNEL_MESSAGE -
@@ -357,10 +281,10 @@ static int create_gpadl_header(void *kbuffer, u32 size,
 		gpadl_header->range_buflen = sizeof(struct gpa_range) +
 					 pagecount * sizeof(u64);
 		gpadl_header->range[0].byte_offset = 0;
-		gpadl_header->range[0].byte_count = size;
+		gpadl_header->range[0].byte_count = hv_gpadl_size(type, size);
 		for (i = 0; i < pfncount; i++)
-			gpadl_header->range[0].pfn_array[i] = virt_to_hvpfn(
-				kbuffer + PAGE_SIZE * i);
+			gpadl_header->range[0].pfn_array[i] = hv_gpadl_hvpfn(
+				type, kbuffer, size, send_offset, i);
 		*msginfo = msgheader;
 
 		pfnsum = pfncount;
@@ -411,8 +335,8 @@ static int create_gpadl_header(void *kbuffer, u32 size,
 			 * so the hypervisor guarantees that this is ok.
 			 */
 			for (i = 0; i < pfncurr; i++)
-				gpadl_body->pfn[i] = virt_to_hvpfn(
-					kbuffer + PAGE_SIZE * (pfnsum + i));
+				gpadl_body->pfn[i] = hv_gpadl_hvpfn(type,
+					kbuffer, size, send_offset, pfnsum + i);
 
 			/* add to msg header */
 			list_add_tail(&msgbody->msglistentry,
@@ -438,10 +362,10 @@ static int create_gpadl_header(void *kbuffer, u32 size,
 		gpadl_header->range_buflen = sizeof(struct gpa_range) +
 					 pagecount * sizeof(u64);
 		gpadl_header->range[0].byte_offset = 0;
-		gpadl_header->range[0].byte_count = size;
+		gpadl_header->range[0].byte_count = hv_gpadl_size(type, size);
 		for (i = 0; i < pagecount; i++)
-			gpadl_header->range[0].pfn_array[i] = virt_to_hvpfn(
-				kbuffer + PAGE_SIZE * i);
+			gpadl_header->range[0].pfn_array[i] = hv_gpadl_hvpfn(
+				type, kbuffer, size, send_offset, i);
 
 		*msginfo = msgheader;
 	}
@@ -454,15 +378,20 @@ nomem:
 }
 
 /*
- * vmbus_establish_gpadl - Establish a GPADL for the specified buffer
+ * __vmbus_establish_gpadl - Establish a GPADL for a buffer or ringbuffer
  *
  * @channel: a channel
+ * @type: the type of the corresponding GPADL, only meaningful for the guest.
  * @kbuffer: from kmalloc or vmalloc
  * @size: page-size multiple
+ * @send_offset: the offset (in bytes) where the send ring buffer starts,
+ * 		 should be 0 for BUFFER type gpadl
  * @gpadl_handle: some funky thing
  */
-int vmbus_establish_gpadl(struct vmbus_channel *channel, void *kbuffer,
-			       u32 size, u32 *gpadl_handle)
+static int __vmbus_establish_gpadl(struct vmbus_channel *channel,
+				   enum hv_gpadl_type type, void *kbuffer,
+				   u32 size, u32 send_offset,
+				   u32 *gpadl_handle)
 {
 	struct vmbus_channel_gpadl_header *gpadlmsg;
 	struct vmbus_channel_gpadl_body *gpadl_body;
@@ -476,7 +405,7 @@ int vmbus_establish_gpadl(struct vmbus_channel *channel, void *kbuffer,
 	next_gpadl_handle =
 		(atomic_inc_return(&vmbus_connection.next_gpadl_handle) - 1);
 
-	ret = create_gpadl_header(kbuffer, size, &msginfo);
+	ret = create_gpadl_header(type, kbuffer, size, send_offset, &msginfo);
 	if (ret)
 		return ret;
 
@@ -557,8 +486,184 @@ cleanup:
 	kfree(msginfo);
 	return ret;
 }
+
+/*
+ * vmbus_establish_gpadl - Establish a GPADL for the specified buffer
+ *
+ * @channel: a channel
+ * @kbuffer: from kmalloc or vmalloc
+ * @size: page-size multiple
+ * @gpadl_handle: some funky thing
+ */
+int vmbus_establish_gpadl(struct vmbus_channel *channel, void *kbuffer,
+			  u32 size, u32 *gpadl_handle)
+{
+	return __vmbus_establish_gpadl(channel, HV_GPADL_BUFFER, kbuffer, size,
+				       0U, gpadl_handle);
+}
 EXPORT_SYMBOL_GPL(vmbus_establish_gpadl);
 
+static int __vmbus_open(struct vmbus_channel *newchannel,
+		       void *userdata, u32 userdatalen,
+		       void (*onchannelcallback)(void *context), void *context)
+{
+	struct vmbus_channel_open_channel *open_msg;
+	struct vmbus_channel_msginfo *open_info = NULL;
+	struct page *page = newchannel->ringbuffer_page;
+	u32 send_pages, recv_pages;
+	unsigned long flags;
+	int err;
+
+	if (userdatalen > MAX_USER_DEFINED_BYTES)
+		return -EINVAL;
+
+	send_pages = newchannel->ringbuffer_send_offset;
+	recv_pages = newchannel->ringbuffer_pagecount - send_pages;
+
+	if (newchannel->state != CHANNEL_OPEN_STATE)
+		return -EINVAL;
+
+	newchannel->state = CHANNEL_OPENING_STATE;
+	newchannel->onchannel_callback = onchannelcallback;
+	newchannel->channel_callback_context = context;
+
+	err = hv_ringbuffer_init(&newchannel->outbound, page, send_pages);
+	if (err)
+		goto error_clean_ring;
+
+	err = hv_ringbuffer_init(&newchannel->inbound,
+				 &page[send_pages], recv_pages);
+	if (err)
+		goto error_clean_ring;
+
+	/* Establish the gpadl for the ring buffer */
+	newchannel->ringbuffer_gpadlhandle = 0;
+
+	err = __vmbus_establish_gpadl(newchannel, HV_GPADL_RING,
+				      page_address(newchannel->ringbuffer_page),
+				      (send_pages + recv_pages) << PAGE_SHIFT,
+				      newchannel->ringbuffer_send_offset << PAGE_SHIFT,
+				      &newchannel->ringbuffer_gpadlhandle);
+	if (err)
+		goto error_clean_ring;
+
+	/* Create and init the channel open message */
+	open_info = kmalloc(sizeof(*open_info) +
+			   sizeof(struct vmbus_channel_open_channel),
+			   GFP_KERNEL);
+	if (!open_info) {
+		err = -ENOMEM;
+		goto error_free_gpadl;
+	}
+
+	init_completion(&open_info->waitevent);
+	open_info->waiting_channel = newchannel;
+
+	open_msg = (struct vmbus_channel_open_channel *)open_info->msg;
+	open_msg->header.msgtype = CHANNELMSG_OPENCHANNEL;
+	open_msg->openid = newchannel->offermsg.child_relid;
+	open_msg->child_relid = newchannel->offermsg.child_relid;
+	open_msg->ringbuffer_gpadlhandle = newchannel->ringbuffer_gpadlhandle;
+	/*
+	 * The unit of ->downstream_ringbuffer_pageoffset is HV_HYP_PAGE and
+	 * the unit of ->ringbuffer_send_offset (i.e. send_pages) is PAGE, so
+	 * here we calculate it into HV_HYP_PAGE.
+	 */
+	open_msg->downstream_ringbuffer_pageoffset =
+		hv_ring_gpadl_send_hvpgoffset(send_pages << PAGE_SHIFT);
+	open_msg->target_vp = hv_cpu_number_to_vp_number(newchannel->target_cpu);
+
+	if (userdatalen)
+		memcpy(open_msg->userdata, userdata, userdatalen);
+
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	list_add_tail(&open_info->msglistentry,
+		      &vmbus_connection.chn_msg_list);
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+
+	if (newchannel->rescind) {
+		err = -ENODEV;
+		goto error_free_info;
+	}
+
+	err = vmbus_post_msg(open_msg,
+			     sizeof(struct vmbus_channel_open_channel), true);
+
+	trace_vmbus_open(open_msg, err);
+
+	if (err != 0)
+		goto error_clean_msglist;
+
+	wait_for_completion(&open_info->waitevent);
+
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	list_del(&open_info->msglistentry);
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+
+	if (newchannel->rescind) {
+		err = -ENODEV;
+		goto error_free_info;
+	}
+
+	if (open_info->response.open_result.status) {
+		err = -EAGAIN;
+		goto error_free_info;
+	}
+
+	newchannel->state = CHANNEL_OPENED_STATE;
+	kfree(open_info);
+	return 0;
+
+error_clean_msglist:
+	spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
+	list_del(&open_info->msglistentry);
+	spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
+error_free_info:
+	kfree(open_info);
+error_free_gpadl:
+	vmbus_teardown_gpadl(newchannel, newchannel->ringbuffer_gpadlhandle);
+	newchannel->ringbuffer_gpadlhandle = 0;
+error_clean_ring:
+	hv_ringbuffer_cleanup(&newchannel->outbound);
+	hv_ringbuffer_cleanup(&newchannel->inbound);
+	newchannel->state = CHANNEL_OPEN_STATE;
+	return err;
+}
+
+/*
+ * vmbus_connect_ring - Open the channel but reuse ring buffer
+ */
+int vmbus_connect_ring(struct vmbus_channel *newchannel,
+		       void (*onchannelcallback)(void *context), void *context)
+{
+	return  __vmbus_open(newchannel, NULL, 0, onchannelcallback, context);
+}
+EXPORT_SYMBOL_GPL(vmbus_connect_ring);
+
+/*
+ * vmbus_open - Open the specified channel.
+ */
+int vmbus_open(struct vmbus_channel *newchannel,
+	       u32 send_ringbuffer_size, u32 recv_ringbuffer_size,
+	       void *userdata, u32 userdatalen,
+	       void (*onchannelcallback)(void *context), void *context)
+{
+	int err;
+
+	err = vmbus_alloc_ring(newchannel, send_ringbuffer_size,
+			       recv_ringbuffer_size);
+	if (err)
+		return err;
+
+	err = __vmbus_open(newchannel, userdata, userdatalen,
+			   onchannelcallback, context);
+	if (err)
+		vmbus_free_ring(newchannel);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(vmbus_open);
+
 /*
  * vmbus_teardown_gpadl -Teardown the specified GPADL handle
  */
diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
index 591106cf58fc..1d44bb635bb8 100644
--- a/drivers/hv/channel_mgmt.c
+++ b/drivers/hv/channel_mgmt.c
@@ -731,7 +731,7 @@ static void vmbus_wait_for_unload(void)
 	void *page_addr;
 	struct hv_message *msg;
 	struct vmbus_channel_message_header *hdr;
-	u32 message_type;
+	u32 message_type, i;
 
 	/*
 	 * CHANNELMSG_UNLOAD_RESPONSE is always delivered to the CPU which was
@@ -741,8 +741,11 @@ static void vmbus_wait_for_unload(void)
 	 * functional and vmbus_unload_response() will complete
 	 * vmbus_connection.unload_event. If not, the last thing we can do is
 	 * read message pages for all CPUs directly.
+	 *
+	 * Wait no more than 10 seconds so that the panic path can't get
+	 * hung forever in case the response message isn't seen.
 	 */
-	while (1) {
+	for (i = 0; i < 1000; i++) {
 		if (completion_done(&vmbus_connection.unload_event))
 			break;
 
diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
index da69338f92f5..410f1fab519c 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -165,7 +165,7 @@ void hv_synic_enable_regs(unsigned int cpu)
 	hv_get_simp(simp.as_uint64);
 	simp.simp_enabled = 1;
 	simp.base_simp_gpa = virt_to_phys(hv_cpu->synic_message_page)
-		>> PAGE_SHIFT;
+		>> HV_HYP_PAGE_SHIFT;
 
 	hv_set_simp(simp.as_uint64);
 
@@ -173,7 +173,7 @@ void hv_synic_enable_regs(unsigned int cpu)
 	hv_get_siefp(siefp.as_uint64);
 	siefp.siefp_enabled = 1;
 	siefp.base_siefp_gpa = virt_to_phys(hv_cpu->synic_event_page)
-		>> PAGE_SHIFT;
+		>> HV_HYP_PAGE_SHIFT;
 
 	hv_set_siefp(siefp.as_uint64);
 
diff --git a/drivers/hv/hv_kvp.c b/drivers/hv/hv_kvp.c
index e74b144b8f3d..754d35a25a1c 100644
--- a/drivers/hv/hv_kvp.c
+++ b/drivers/hv/hv_kvp.c
@@ -354,7 +354,7 @@ static void process_ib_ipinfo(void *in_msg, void *out_msg, int op)
 
 		out->body.kvp_ip_val.dhcp_enabled = in->kvp_ip_val.dhcp_enabled;
 
-		/* fallthrough */
+		fallthrough;
 
 	case KVP_OP_GET_IP_INFO:
 		utf16s_to_utf8s((wchar_t *)in->kvp_ip_val.adapter_id,
diff --git a/drivers/hv/hv_util.c b/drivers/hv/hv_util.c
index 92ee0fe4c919..05566ecdbe4b 100644
--- a/drivers/hv/hv_util.c
+++ b/drivers/hv/hv_util.c
@@ -282,26 +282,52 @@ static struct {
 	spinlock_t			lock;
 } host_ts;
 
-static struct timespec64 hv_get_adj_host_time(void)
+static inline u64 reftime_to_ns(u64 reftime)
 {
-	struct timespec64 ts;
-	u64 newtime, reftime;
+	return (reftime - WLTIMEDELTA) * 100;
+}
+
+/*
+ * Hard coded threshold for host timesync delay: 600 seconds
+ */
+static const u64 HOST_TIMESYNC_DELAY_THRESH = 600 * (u64)NSEC_PER_SEC;
+
+static int hv_get_adj_host_time(struct timespec64 *ts)
+{
+	u64 newtime, reftime, timediff_adj;
 	unsigned long flags;
+	int ret = 0;
 
 	spin_lock_irqsave(&host_ts.lock, flags);
 	reftime = hv_read_reference_counter();
-	newtime = host_ts.host_time + (reftime - host_ts.ref_time);
-	ts = ns_to_timespec64((newtime - WLTIMEDELTA) * 100);
+
+	/*
+	 * We need to let the caller know that last update from host
+	 * is older than the max allowable threshold. clock_gettime()
+	 * and PTP ioctl do not have a documented error that we could
+	 * return for this specific case. Use ESTALE to report this.
+	 */
+	timediff_adj = reftime - host_ts.ref_time;
+	if (timediff_adj * 100 > HOST_TIMESYNC_DELAY_THRESH) {
+		pr_warn_once("TIMESYNC IC: Stale time stamp, %llu nsecs old\n",
+			     (timediff_adj * 100));
+		ret = -ESTALE;
+	}
+
+	newtime = host_ts.host_time + timediff_adj;
+	*ts = ns_to_timespec64(reftime_to_ns(newtime));
 	spin_unlock_irqrestore(&host_ts.lock, flags);
 
-	return ts;
+	return ret;
 }
 
 static void hv_set_host_time(struct work_struct *work)
 {
-	struct timespec64 ts = hv_get_adj_host_time();
 
-	do_settimeofday64(&ts);
+	struct timespec64 ts;
+
+	if (!hv_get_adj_host_time(&ts))
+		do_settimeofday64(&ts);
 }
 
 /*
@@ -361,10 +387,23 @@ static void timesync_onchannelcallback(void *context)
 	struct ictimesync_ref_data *refdata;
 	u8 *time_txf_buf = util_timesynch.recv_buffer;
 
-	vmbus_recvpacket(channel, time_txf_buf,
-			 HV_HYP_PAGE_SIZE, &recvlen, &requestid);
+	/*
+	 * Drain the ring buffer and use the last packet to update
+	 * host_ts
+	 */
+	while (1) {
+		int ret = vmbus_recvpacket(channel, time_txf_buf,
+					   HV_HYP_PAGE_SIZE, &recvlen,
+					   &requestid);
+		if (ret) {
+			pr_warn_once("TimeSync IC pkt recv failed (Err: %d)\n",
+				     ret);
+			break;
+		}
+
+		if (!recvlen)
+			break;
 
-	if (recvlen > 0) {
 		icmsghdrp = (struct icmsg_hdr *)&time_txf_buf[
 				sizeof(struct vmbuspipe_hdr)];
 
@@ -461,6 +500,9 @@ static void heartbeat_onchannelcallback(void *context)
 	}
 }
 
+#define HV_UTIL_RING_SEND_SIZE VMBUS_RING_SIZE(3 * HV_HYP_PAGE_SIZE)
+#define HV_UTIL_RING_RECV_SIZE VMBUS_RING_SIZE(3 * HV_HYP_PAGE_SIZE)
+
 static int util_probe(struct hv_device *dev,
 			const struct hv_vmbus_device_id *dev_id)
 {
@@ -491,8 +533,8 @@ static int util_probe(struct hv_device *dev,
 
 	hv_set_drvdata(dev, srv);
 
-	ret = vmbus_open(dev->channel, 4 * HV_HYP_PAGE_SIZE,
-			 4 * HV_HYP_PAGE_SIZE, NULL, 0, srv->util_cb,
+	ret = vmbus_open(dev->channel, HV_UTIL_RING_SEND_SIZE,
+			 HV_UTIL_RING_RECV_SIZE, NULL, 0, srv->util_cb,
 			 dev->channel);
 	if (ret)
 		goto error;
@@ -551,8 +593,8 @@ static int util_resume(struct hv_device *dev)
 			return ret;
 	}
 
-	ret = vmbus_open(dev->channel, 4 * HV_HYP_PAGE_SIZE,
-			 4 * HV_HYP_PAGE_SIZE, NULL, 0, srv->util_cb,
+	ret = vmbus_open(dev->channel, HV_UTIL_RING_SEND_SIZE,
+			 HV_UTIL_RING_RECV_SIZE, NULL, 0, srv->util_cb,
 			 dev->channel);
 	return ret;
 }
@@ -622,9 +664,7 @@ static int hv_ptp_adjtime(struct ptp_clock_info *ptp, s64 delta)
 
 static int hv_ptp_gettime(struct ptp_clock_info *info, struct timespec64 *ts)
 {
-	*ts = hv_get_adj_host_time();
-
-	return 0;
+	return hv_get_adj_host_time(ts);
 }
 
 static struct ptp_clock_info ptp_hyperv_info = {
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 910b6e90866c..7b8816c2e5f9 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -83,7 +83,7 @@ static int hyperv_panic_event(struct notifier_block *nb, unsigned long val,
 static int hyperv_die_event(struct notifier_block *nb, unsigned long val,
 			    void *args)
 {
-	struct die_args *die = (struct die_args *)args;
+	struct die_args *die = args;
 	struct pt_regs *regs = die->regs;
 
 	/* Don't notify Hyper-V if the die event is other than oops */
@@ -2382,7 +2382,10 @@ static int vmbus_bus_suspend(struct device *dev)
 	if (atomic_read(&vmbus_connection.nr_chan_close_on_suspend) > 0)
 		wait_for_completion(&vmbus_connection.ready_for_suspend_event);
 
-	WARN_ON(atomic_read(&vmbus_connection.nr_chan_fixup_on_resume) != 0);
+	if (atomic_read(&vmbus_connection.nr_chan_fixup_on_resume) != 0) {
+		pr_err("Can not suspend due to a previous failed resuming\n");
+		return -EBUSY;
+	}
 
 	mutex_lock(&vmbus_connection.channel_mutex);
 
@@ -2456,7 +2459,9 @@ static int vmbus_bus_resume(struct device *dev)
 
 	vmbus_request_offers();
 
-	wait_for_completion(&vmbus_connection.ready_for_resume_event);
+	if (wait_for_completion_timeout(
+		&vmbus_connection.ready_for_resume_event, 10 * HZ) == 0)
+		pr_err("Some vmbus device is missing after suspending?\n");
 
 	/* Reset the event for the next suspend. */
 	reinit_completion(&vmbus_connection.ready_for_suspend_event);