[Xen-devel] [PATCH V2] qemu-xen: HVM domain S3 bugfix

["Liu, Jinsong" <jinsong.liu@xxxxxxxxx>]

Currently HVM S3 has a bug coming from the difference between
qemu-traditioanl and qemu-xen. For qemu-traditional, the way
to resume from hvm s3 is via 'xl trigger' command. However,
for qemu-xen, the way to resume from hvm s3 inherited from
standard qemu, i.e. via QMP, and it doesn't work under Xen.

The root cause is, for qemu-xen, 'xl trigger' command didn't reset
devices, while QMP didn't unpause hvm domain though they did qemu
system reset.

We have 2 patches to fix the HVM S3 bug: qemu-xen patch and xl patch.
This patch is the qemu-xen patch. It registers a wakeup later notify,
so that when 'xl trigger' command invokes QMP system_wakeup and after
qemu system reset, it hypercalls to hypervisor to unpause domain, then
hvm S3 resumes successfully.

Signed-off-by: Liu Jinsong <jinsong.liu@xxxxxxxxx>
---
 vl.c      |   13 +++++++++++++
 xen-all.c |    9 +++++++++
 2 files changed, 22 insertions(+), 0 deletions(-)

diff --git a/vl.c b/vl.c
index 5314f55..aeebd83 100644
--- a/vl.c
+++ b/vl.c
@@ -1478,6 +1478,8 @@ static NotifierList suspend_notifiers =
     NOTIFIER_LIST_INITIALIZER(suspend_notifiers);
 static NotifierList wakeup_notifiers =
     NOTIFIER_LIST_INITIALIZER(wakeup_notifiers);
+static NotifierList wakeup_later_notifiers =
+    NOTIFIER_LIST_INITIALIZER(wakeup_later_notifiers);
 static uint32_t wakeup_reason_mask = ~0;
 static RunState vmstop_requested = RUN_STATE_MAX;
 
@@ -1625,6 +1627,11 @@ static void qemu_system_suspend(void)
     monitor_protocol_event(QEVENT_SUSPEND, NULL);
 }
 
+static void qemu_system_wakeup(void)
+{
+    notifier_list_notify(&wakeup_later_notifiers, NULL);
+}
+
 void qemu_system_suspend_request(void)
 {
     if (runstate_check(RUN_STATE_SUSPENDED)) {
@@ -1668,6 +1675,11 @@ void qemu_register_wakeup_notifier(Notifier *notifier)
     notifier_list_add(&wakeup_notifiers, notifier);
 }
 
+void qemu_register_wakeup_later_notifier(Notifier *notifier)
+{
+    notifier_list_add(&wakeup_later_notifiers, notifier);
+}
+
 void qemu_system_killed(int signal, pid_t pid)
 {
     shutdown_signal = signal;
@@ -1744,6 +1756,7 @@ static bool main_loop_should_exit(void)
         cpu_synchronize_all_states();
         qemu_system_reset(VMRESET_SILENT);
         resume_all_vcpus();
+        qemu_system_wakeup();
         monitor_protocol_event(QEVENT_WAKEUP, NULL);
     }
     if (qemu_powerdown_requested()) {
diff --git a/xen-all.c b/xen-all.c
index 15be8ed..3353f63 100644
--- a/xen-all.c
+++ b/xen-all.c
@@ -97,6 +97,7 @@ typedef struct XenIOState {
 
     Notifier exit;
     Notifier suspend;
+    Notifier wakeup_later;
 } XenIOState;
 
 /* Xen specific function for piix pci */
@@ -139,6 +140,11 @@ static void xen_suspend_notifier(Notifier *notifier, void 
*data)
     xc_set_hvm_param(xen_xc, xen_domid, HVM_PARAM_ACPI_S_STATE, 3);
 }
 
+static void xen_wakeup_later_notifier(Notifier *notifier, void *data)
+{
+    xc_set_hvm_param(xen_xc, xen_domid, HVM_PARAM_ACPI_S_STATE, 0);
+}
+
 /* Xen Interrupt Controller */
 
 static void xen_set_irq(void *opaque, int irq, int level)
@@ -1106,6 +1112,9 @@ int xen_hvm_init(void)
     state->suspend.notify = xen_suspend_notifier;
     qemu_register_suspend_notifier(&state->suspend);
 
+    state->wakeup_later.notify = xen_wakeup_later_notifier;
+    qemu_register_wakeup_later_notifier(&state->wakeup_later);
+
     xc_get_hvm_param(xen_xc, xen_domid, HVM_PARAM_IOREQ_PFN, &ioreq_pfn);
     DPRINTF("shared page at pfn %lx\n", ioreq_pfn);
     state->shared_page = xc_map_foreign_range(xen_xc, xen_domid, XC_PAGE_SIZE,
-- 
1.7.1

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