xen: implement save/restore
This patch implements Xen save/restore and migration.
Saving is triggered via xenbus, which is polled in
drivers/xen/manage.c. When a suspend request comes in, the kernel
prepares itself for saving by:
1 - Freeze all processes. This is primarily to prevent any
partially-completed pagetable updates from confusing the suspend
process. If CONFIG_PREEMPT isn't defined, then this isn't necessary.
2 - Suspend xenbus and other devices
3 - Stop_machine, to make sure all the other vcpus are quiescent. The
Xen tools require the domain to run its save off vcpu0.
4 - Within the stop_machine state, it pins any unpinned pgds (under
construction or destruction), performs canonicalizes various other
pieces of state (mostly converting mfns to pfns), and finally
5 - Suspend the domain
Restore reverses the steps used to save the domain, ending when all
the frozen processes are thawed.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
diff --git a/arch/x86/xen/suspend.c b/arch/x86/xen/suspend.c
new file mode 100644
index 0000000..7620a16
--- /dev/null
+++ b/arch/x86/xen/suspend.c
@@ -0,0 +1,42 @@
+#include <linux/types.h>
+
+#include <xen/interface/xen.h>
+#include <xen/grant_table.h>
+#include <xen/events.h>
+
+#include <asm/xen/hypercall.h>
+#include <asm/xen/page.h>
+
+#include "xen-ops.h"
+#include "mmu.h"
+
+void xen_pre_suspend(void)
+{
+ xen_start_info->store_mfn = mfn_to_pfn(xen_start_info->store_mfn);
+ xen_start_info->console.domU.mfn =
+ mfn_to_pfn(xen_start_info->console.domU.mfn);
+
+ BUG_ON(!irqs_disabled());
+
+ HYPERVISOR_shared_info = &xen_dummy_shared_info;
+ if (HYPERVISOR_update_va_mapping(fix_to_virt(FIX_PARAVIRT_BOOTMAP),
+ __pte_ma(0), 0))
+ BUG();
+}
+
+void xen_post_suspend(int suspend_cancelled)
+{
+ if (suspend_cancelled) {
+ xen_start_info->store_mfn =
+ pfn_to_mfn(xen_start_info->store_mfn);
+ xen_start_info->console.domU.mfn =
+ pfn_to_mfn(xen_start_info->console.domU.mfn);
+ } else {
+#ifdef CONFIG_SMP
+ xen_cpu_initialized_map = cpu_online_map;
+#endif
+ }
+
+ xen_setup_shared_info();
+}
+