[RFC PATCH 05/12] x86/xen: add system core suspend and resume callbacks

[Anchal Agarwal <anchalag@amazon.com>]

From: Munehisa Kamata <kamatam@amazon.com>

Add Xen PVHVM specific system core callbacks for PM suspend and
hibernation support. The callbacks suspend and resume Xen primitives,
like shared_info, pvclock and grant table. Note that Xen suspend can
handle them in a different manner, but system core callbacks are called
from the context. So if the callbacks are called from Xen suspend
context, return immediately.

Signed-off-by: Munehisa Kamata <kamatam@amazon.com>
Signed-off-by: Anchal Agarwal <anchalag@amazon.com>
Reviewed-by: Munehisa Kamata <kamatam@amazon.com>
Reviewed-by: Eduardo Valentin <eduval@amazon.com>
---
 arch/x86/xen/enlighten_hvm.c |  1 +
 arch/x86/xen/suspend.c       | 53 ++++++++++++++++++++++++++++++++++++++++++++
 include/xen/xen-ops.h        |  2 ++
 3 files changed, 56 insertions(+)

diff --git a/arch/x86/xen/enlighten_hvm.c b/arch/x86/xen/enlighten_hvm.c
index d24ad16..4196a65 100644
--- a/arch/x86/xen/enlighten_hvm.c
+++ b/arch/x86/xen/enlighten_hvm.c
@@ -202,6 +202,7 @@ static void __init xen_hvm_guest_init(void)
 	if (xen_feature(XENFEAT_hvm_callback_vector))
 		xen_have_vector_callback = 1;
 
+	xen_setup_syscore_ops();
 	xen_hvm_smp_init();
 	WARN_ON(xen_cpuhp_setup(xen_cpu_up_prepare_hvm, xen_cpu_dead_hvm));
 	xen_unplug_emulated_devices();
diff --git a/arch/x86/xen/suspend.c b/arch/x86/xen/suspend.c
index 1d83152..784c448 100644
--- a/arch/x86/xen/suspend.c
+++ b/arch/x86/xen/suspend.c
@@ -2,17 +2,22 @@
 #include <linux/types.h>
 #include <linux/tick.h>
 #include <linux/percpu-defs.h>
+#include <linux/syscore_ops.h>
+#include <linux/kernel_stat.h>
 
 #include <xen/xen.h>
 #include <xen/interface/xen.h>
+#include <xen/interface/memory.h>
 #include <xen/grant_table.h>
 #include <xen/events.h>
+#include <xen/xen-ops.h>
 
 #include <asm/cpufeatures.h>
 #include <asm/msr-index.h>
 #include <asm/xen/hypercall.h>
 #include <asm/xen/page.h>
 #include <asm/fixmap.h>
+#include <asm/pvclock.h>
 
 #include "xen-ops.h"
 #include "mmu.h"
@@ -82,3 +87,51 @@ void xen_arch_suspend(void)
 
 	on_each_cpu(xen_vcpu_notify_suspend, NULL, 1);
 }
+
+static int xen_syscore_suspend(void)
+{
+	struct xen_remove_from_physmap xrfp;
+	int ret;
+
+	/* Xen suspend does similar stuffs in its own logic */
+	if (xen_suspend_mode_is_xen_suspend())
+		return 0;
+
+	xrfp.domid = DOMID_SELF;
+	xrfp.gpfn = __pa(HYPERVISOR_shared_info) >> PAGE_SHIFT;
+
+	ret = HYPERVISOR_memory_op(XENMEM_remove_from_physmap, &xrfp);
+	if (!ret)
+		HYPERVISOR_shared_info = &xen_dummy_shared_info;
+
+	return ret;
+}
+
+static void xen_syscore_resume(void)
+{
+	/* Xen suspend does similar stuffs in its own logic */
+	if (xen_suspend_mode_is_xen_suspend())
+		return;
+
+	/* No need to setup vcpu_info as it's already moved off */
+	xen_hvm_map_shared_info();
+
+	pvclock_resume();
+
+	gnttab_resume();
+}
+
+/*
+ * These callbacks will be called with interrupts disabled and when having only
+ * one CPU online.
+ */
+static struct syscore_ops xen_hvm_syscore_ops = {
+	.suspend = xen_syscore_suspend,
+	.resume = xen_syscore_resume
+};
+
+void __init xen_setup_syscore_ops(void)
+{
+	if (xen_hvm_domain())
+		register_syscore_ops(&xen_hvm_syscore_ops);
+}
diff --git a/include/xen/xen-ops.h b/include/xen/xen-ops.h
index be78f6f..65f25bd 100644
--- a/include/xen/xen-ops.h
+++ b/include/xen/xen-ops.h
@@ -43,6 +43,8 @@ bool xen_suspend_mode_is_xen_suspend(void);
 bool xen_suspend_mode_is_pm_suspend(void);
 bool xen_suspend_mode_is_pm_hibernation(void);
 
+void xen_setup_syscore_ops(void);
+
 extern unsigned long *xen_contiguous_bitmap;
 
 #ifdef CONFIG_XEN_PV
-- 
2.7.4