Merge tag 'hyperv-fixes-signed-20240303' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux

Pull hyperv fixes from Wei Liu:

 - Multiple fixes, cleanups and documentations for Hyper-V core code and
   drivers

* tag 'hyperv-fixes-signed-20240303' of git://git.kernel.org/pub/scm/linux/kernel/git/hyperv/linux:
  Drivers: hv: vmbus: make hv_bus const
  x86/hyperv: Allow 15-bit APIC IDs for VTL platforms
  x86/hyperv: Make encrypted/decrypted changes safe for load_unaligned_zeropad()
  x86/mm: Regularize set_memory_p() parameters and make non-static
  x86/hyperv: Use slow_virt_to_phys() in page transition hypervisor callback
  Documentation: hyperv: Add overview of PCI pass-thru device support
  Drivers: hv: vmbus: Update indentation in create_gpadl_header()
  Drivers: hv: vmbus: Remove duplication and cleanup code in create_gpadl_header()
  fbdev/hyperv_fb: Fix logic error for Gen2 VMs in hvfb_getmem()
  Drivers: hv: vmbus: Calculate ring buffer size for more efficient use of memory
  hv_utils: Allow implicit ICTIMESYNCFLAG_SYNC

4 files changed, 101 insertions, 110 deletions

diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index 56f7e06c673e..adbf674355b2 100644
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -322,125 +322,89 @@ 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;
 }
 
 /*
diff --git a/drivers/hv/hv_util.c b/drivers/hv/hv_util.c
index 42aec2c5606a..9c97c4065fe7 100644
--- a/drivers/hv/hv_util.c
+++ b/drivers/hv/hv_util.c
@@ -296,6 +296,11 @@ static struct {
 	spinlock_t			lock;
 } host_ts;
 
+static bool timesync_implicit;
+
+module_param(timesync_implicit, bool, 0644);
+MODULE_PARM_DESC(timesync_implicit, "If set treat SAMPLE as SYNC when clock is behind");
+
 static inline u64 reftime_to_ns(u64 reftime)
 {
 	return (reftime - WLTIMEDELTA) * 100;
@@ -345,6 +350,29 @@ static void hv_set_host_time(struct work_struct *work)
 }
 
 /*
+ * Due to a bug on Hyper-V hosts, the sync flag may not always be sent on resume.
+ * Force a sync if the guest is behind.
+ */
+static inline bool hv_implicit_sync(u64 host_time)
+{
+	struct timespec64 new_ts;
+	struct timespec64 threshold_ts;
+
+	new_ts = ns_to_timespec64(reftime_to_ns(host_time));
+	ktime_get_real_ts64(&threshold_ts);
+
+	threshold_ts.tv_sec += 5;
+
+	/*
+	 * If guest behind the host by 5 or more seconds.
+	 */
+	if (timespec64_compare(&new_ts, &threshold_ts) >= 0)
+		return true;
+
+	return false;
+}
+
+/*
  * Synchronize time with host after reboot, restore, etc.
  *
  * ICTIMESYNCFLAG_SYNC flag bit indicates reboot, restore events of the VM.
@@ -384,7 +412,8 @@ static inline void adj_guesttime(u64 hosttime, u64 reftime, u8 adj_flags)
 	spin_unlock_irqrestore(&host_ts.lock, flags);
 
 	/* Schedule work to do do_settimeofday64() */
-	if (adj_flags & ICTIMESYNCFLAG_SYNC)
+	if ((adj_flags & ICTIMESYNCFLAG_SYNC) ||
+	    (timesync_implicit && hv_implicit_sync(host_ts.host_time)))
 		schedule_work(&adj_time_work);
 }
 
diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index b33d5abd9beb..7f7965f3d187 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -988,7 +988,7 @@ static const struct dev_pm_ops vmbus_pm = {
 };
 
 /* The one and only one */
-static struct bus_type  hv_bus = {
+static const struct bus_type  hv_bus = {
 	.name =		"vmbus",
 	.match =		vmbus_match,
 	.shutdown =		vmbus_shutdown,
diff --git a/drivers/video/fbdev/hyperv_fb.c b/drivers/video/fbdev/hyperv_fb.c
index c26ee6fd73c9..8fdccf033b2d 100644
--- a/drivers/video/fbdev/hyperv_fb.c
+++ b/drivers/video/fbdev/hyperv_fb.c
@@ -1010,8 +1010,6 @@ static int hvfb_getmem(struct hv_device *hdev, struct fb_info *info)
 			goto getmem_done;
 		}
 		pr_info("Unable to allocate enough contiguous physical memory on Gen 1 VM. Using MMIO instead.\n");
-	} else {
-		goto err1;
 	}
 
 	/*