[PATCH] Drivers: hv: vmbus: Fix Suspend-to-Idle for Generation-2 VM

From: Dexuan Cui <decui@microsoft.com>
To: kys@microsoft.com, haiyangz@microsoft.com,
	sthemmin@microsoft.com, wei.liu@kernel.org,
	linux-hyperv@vger.kernel.org, linux-kernel@vger.kernel.org,
	mikelley@microsoft.com, vkuznets@redhat.com
Cc: Dexuan Cui <decui@microsoft.com>, stable@vger.kernel.org
Subject: [PATCH] Drivers: hv: vmbus: Fix Suspend-to-Idle for Generation-2 VM
Date: Fri, 10 Apr 2020 15:17:35 -0700	[thread overview]
Message-ID: <1586557055-13776-1-git-send-email-decui@microsoft.com> (raw)

Before the hibernation patchset (e.g. f53335e3289f), in a Generation-2
Linux VM on Hyper-V, the user can run "echo freeze > /sys/power/state" to
freeze the system, i.e. Suspend-to-Idle. The user can press the keyboard
or move the mouse to wake up the VM.

With the hibernation patchset, Linux VM on Hyper-V can hibernate to disk,
but Suspend-to-Idle is broken: when the synthetic keyboard/mouse are
suspended, there is no way to wake up the VM.

Fix the issue by not suspending and resuming the vmbus devices upon
Suspend-to-Idle.

Fixes: f53335e3289f ("Drivers: hv: vmbus: Suspend/resume the vmbus itself for hibernation")
Cc: stable@vger.kernel.org
Signed-off-by: Dexuan Cui <decui@microsoft.com>
---
 drivers/hv/vmbus_drv.c | 37 ++++++++++++++++++++++++++++---------
 1 file changed, 28 insertions(+), 9 deletions(-)

diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c
index 029378c27421..821185d20cbd 100644
--- a/drivers/hv/vmbus_drv.c
+++ b/drivers/hv/vmbus_drv.c
@@ -969,11 +969,22 @@ static void vmbus_device_release(struct device *device)
 }
 
 /*
- * Note: we must use SET_NOIRQ_SYSTEM_SLEEP_PM_OPS rather than
- * SET_SYSTEM_SLEEP_PM_OPS: see the comment before vmbus_bus_pm.
+ * Note: we must use the "noirq" ops: see the comment before vmbus_bus_pm.
+ *
+ * suspend_noirq/resume_noirq are set to NULL to support Suspend-to-Idle: we
+ * shouldn't suspend the vmbus devices upon Suspend-to-Idle, otherwise there
+ * is no way to wake up a Generation-2 VM.
+ *
+ * The other 4 ops are for hibernation.
  */
+
 static const struct dev_pm_ops vmbus_pm = {
-	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(vmbus_suspend, vmbus_resume)
+	.suspend_noirq	= NULL,
+	.resume_noirq	= NULL,
+	.freeze_noirq	= vmbus_suspend,
+	.thaw_noirq	= vmbus_resume,
+	.poweroff_noirq	= vmbus_suspend,
+	.restore_noirq	= vmbus_resume,
 };
 
 /* The one and only one */
@@ -2263,16 +2274,24 @@ static const struct acpi_device_id vmbus_acpi_device_ids[] = {
 MODULE_DEVICE_TABLE(acpi, vmbus_acpi_device_ids);
 
 /*
- * Note: we must use SET_NOIRQ_SYSTEM_SLEEP_PM_OPS rather than
- * SET_SYSTEM_SLEEP_PM_OPS, otherwise NIC SR-IOV can not work, because the
- * "pci_dev_pm_ops" uses the "noirq" callbacks: in the resume path, the
- * pci "noirq" restore callback runs before "non-noirq" callbacks (see
+ * Note: we must use the "no_irq" ops, otherwise hibernation can not work with
+ * PCI device assignment, because "pci_dev_pm_ops" uses the "noirq" ops: in
+ * the resume path, the pci "noirq" restore op runs before "non-noirq" op (see
  * resume_target_kernel() -> dpm_resume_start(), and hibernation_restore() ->
  * dpm_resume_end()). This means vmbus_bus_resume() and the pci-hyperv's
- * resume callback must also run via the "noirq" callbacks.
+ * resume callback must also run via the "noirq" ops.
+ *
+ * Set suspend_noirq/resume_noirq to NULL for Suspend-to-Idle: see the comment
+ * earlier in thie file before vmbus_pm.
  */
+
 static const struct dev_pm_ops vmbus_bus_pm = {
-	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(vmbus_bus_suspend, vmbus_bus_resume)
+	.suspend_noirq	= NULL,
+	.resume_noirq	= NULL,
+	.freeze_noirq	= vmbus_bus_suspend,
+	.thaw_noirq	= vmbus_bus_resume,
+	.poweroff_noirq	= vmbus_bus_suspend,
+	.restore_noirq	= vmbus_bus_resume
 };
 
 static struct acpi_driver vmbus_acpi_driver = {
-- 
2.19.1

