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/Makefile b/arch/x86/xen/Makefile
index 40b119b..2ba2d16 100644
--- a/arch/x86/xen/Makefile
+++ b/arch/x86/xen/Makefile
@@ -1,4 +1,4 @@
obj-y := enlighten.o setup.o multicalls.o mmu.o \
- time.o xen-asm.o grant-table.o
+ time.o xen-asm.o grant-table.o suspend.o
obj-$(CONFIG_SMP) += smp.o
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index ce67dc8..b94f63a 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -857,7 +857,7 @@
PFN_DOWN(__pa(xen_start_info->pt_base)));
}
-static __init void setup_shared_info(void)
+void xen_setup_shared_info(void)
{
if (!xen_feature(XENFEAT_auto_translated_physmap)) {
unsigned long addr = fix_to_virt(FIX_PARAVIRT_BOOTMAP);
@@ -894,7 +894,7 @@
pv_mmu_ops.release_pmd = xen_release_pmd;
pv_mmu_ops.set_pte = xen_set_pte;
- setup_shared_info();
+ xen_setup_shared_info();
/* Actually pin the pagetable down, but we can't set PG_pinned
yet because the page structures don't exist yet. */
@@ -902,7 +902,7 @@
}
/* This is called once we have the cpu_possible_map */
-void __init xen_setup_vcpu_info_placement(void)
+void xen_setup_vcpu_info_placement(void)
{
int cpu;
diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index 4740cda..e959559 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -560,6 +560,29 @@
xen_mc_issue(0);
}
+/*
+ * On save, we need to pin all pagetables to make sure they get their
+ * mfns turned into pfns. Search the list for any unpinned pgds and pin
+ * them (unpinned pgds are not currently in use, probably because the
+ * process is under construction or destruction).
+ */
+void xen_mm_pin_all(void)
+{
+ unsigned long flags;
+ struct page *page;
+
+ spin_lock_irqsave(&pgd_lock, flags);
+
+ list_for_each_entry(page, &pgd_list, lru) {
+ if (!PagePinned(page)) {
+ xen_pgd_pin((pgd_t *)page_address(page));
+ SetPageSavePinned(page);
+ }
+ }
+
+ spin_unlock_irqrestore(&pgd_lock, flags);
+}
+
/* The init_mm pagetable is really pinned as soon as its created, but
that's before we have page structures to store the bits. So do all
the book-keeping now. */
@@ -617,6 +640,29 @@
xen_mc_issue(0);
}
+/*
+ * On resume, undo any pinning done at save, so that the rest of the
+ * kernel doesn't see any unexpected pinned pagetables.
+ */
+void xen_mm_unpin_all(void)
+{
+ unsigned long flags;
+ struct page *page;
+
+ spin_lock_irqsave(&pgd_lock, flags);
+
+ list_for_each_entry(page, &pgd_list, lru) {
+ if (PageSavePinned(page)) {
+ BUG_ON(!PagePinned(page));
+ printk("unpinning pinned %p\n", page_address(page));
+ xen_pgd_unpin((pgd_t *)page_address(page));
+ ClearPageSavePinned(page);
+ }
+ }
+
+ spin_unlock_irqrestore(&pgd_lock, flags);
+}
+
void xen_activate_mm(struct mm_struct *prev, struct mm_struct *next)
{
spin_lock(&next->page_table_lock);
diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index 74ab896..d2e3c20 100644
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -35,7 +35,7 @@
#include "xen-ops.h"
#include "mmu.h"
-static cpumask_t xen_cpu_initialized_map;
+cpumask_t xen_cpu_initialized_map;
static DEFINE_PER_CPU(int, resched_irq) = -1;
static DEFINE_PER_CPU(int, callfunc_irq) = -1;
static DEFINE_PER_CPU(int, debug_irq) = -1;
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();
+}
+
diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index c39e1a5..0bef256 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -572,6 +572,14 @@
clockevents_register_device(&__get_cpu_var(xen_clock_events));
}
+void xen_time_suspend(void)
+{
+}
+
+void xen_time_resume(void)
+{
+}
+
__init void xen_time_init(void)
{
int cpu = smp_processor_id();
diff --git a/arch/x86/xen/xen-ops.h b/arch/x86/xen/xen-ops.h
index a1bc89a..a0503ac 100644
--- a/arch/x86/xen/xen-ops.h
+++ b/arch/x86/xen/xen-ops.h
@@ -9,6 +9,7 @@
extern const char xen_hypervisor_callback[];
extern const char xen_failsafe_callback[];
+struct trap_info;
void xen_copy_trap_info(struct trap_info *traps);
DECLARE_PER_CPU(unsigned long, xen_cr3);
@@ -19,6 +20,7 @@
extern struct shared_info *HYPERVISOR_shared_info;
void xen_setup_mfn_list_list(void);
+void xen_setup_shared_info(void);
char * __init xen_memory_setup(void);
void __init xen_arch_setup(void);
@@ -59,6 +61,8 @@
int xen_smp_call_function_mask(cpumask_t mask, void (*func)(void *),
void *info, int wait);
+extern cpumask_t xen_cpu_initialized_map;
+
/* Declare an asm function, along with symbols needed to make it
inlineable */