qemu: Add qemu xen logic for Xen HVM S3 resume

This patch is qemu patch 2 to fix Xen HVM S3 bug, adding qemu
xen logic. When qemu wakeup, qemu xen logic is notified and
hypercall to xen hypervisor to unpause domain.
Signed-off-by: NLiu Jinsong <jinsong.liu@intel.com>
Signed-off-by: NStefano Stabellini <stefano.stabellini@eu.citrix.com>
Reviewed-by: NAnthony PERARD <anthony.perard@citrix.com>

xen-all.c

@@ -98,6 +98,7 @@ typedef struct XenIOState {
 
     Notifier exit;
     Notifier suspend;
+    Notifier wakeup;
 } XenIOState;
 
 /* Xen specific function for piix pci */
@@ -1060,6 +1061,11 @@ static void xen_read_physmap(XenIOState *state)
     free(entries);
 }
 
+static void xen_wakeup_notifier(Notifier *notifier, void *data)
+{
+    xc_set_hvm_param(xen_xc, xen_domid, HVM_PARAM_ACPI_S_STATE, 0);
+}
+
 int xen_hvm_init(MemoryRegion **ram_memory)
 {
     int i, rc;
@@ -1089,6 +1095,9 @@ int xen_hvm_init(MemoryRegion **ram_memory)
     state->suspend.notify = xen_suspend_notifier;
     qemu_register_suspend_notifier(&state->suspend);
 
+    state->wakeup.notify = xen_wakeup_notifier;
+    qemu_register_wakeup_notifier(&state->wakeup);
+
     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,