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>
This commit is contained in:
Jeremy Fitzhardinge 2008-05-26 23:31:27 +01:00 committed by Thomas Gleixner
parent 7d88d32a46
commit 0e91398f2a
14 changed files with 317 additions and 20 deletions

View file

@ -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

View file

@ -857,7 +857,7 @@ static __init void xen_pagetable_setup_start(pgd_t *base)
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 @@ static __init void xen_pagetable_setup_done(pgd_t *base)
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 @@ static __init void xen_pagetable_setup_done(pgd_t *base)
}
/* 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;

View file

@ -560,6 +560,29 @@ void xen_pgd_pin(pgd_t *pgd)
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 @@ static void xen_pgd_unpin(pgd_t *pgd)
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);

View file

@ -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;

42
arch/x86/xen/suspend.c Normal file
View file

@ -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();
}

View file

@ -572,6 +572,14 @@ void xen_setup_cpu_clockevents(void)
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();

View file

@ -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 xen_dummy_shared_info;
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_single(int cpu, void (*func) (void *info), void *info,
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 */

View file

@ -674,6 +674,89 @@ static int retrigger_dynirq(unsigned int irq)
return ret;
}
static void restore_cpu_virqs(unsigned int cpu)
{
struct evtchn_bind_virq bind_virq;
int virq, irq, evtchn;
for (virq = 0; virq < NR_VIRQS; virq++) {
if ((irq = per_cpu(virq_to_irq, cpu)[virq]) == -1)
continue;
BUG_ON(irq_info[irq].type != IRQT_VIRQ);
BUG_ON(irq_info[irq].index != virq);
/* Get a new binding from Xen. */
bind_virq.virq = virq;
bind_virq.vcpu = cpu;
if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_virq,
&bind_virq) != 0)
BUG();
evtchn = bind_virq.port;
/* Record the new mapping. */
evtchn_to_irq[evtchn] = irq;
irq_info[irq] = mk_irq_info(IRQT_VIRQ, virq, evtchn);
bind_evtchn_to_cpu(evtchn, cpu);
/* Ready for use. */
unmask_evtchn(evtchn);
}
}
static void restore_cpu_ipis(unsigned int cpu)
{
struct evtchn_bind_ipi bind_ipi;
int ipi, irq, evtchn;
for (ipi = 0; ipi < XEN_NR_IPIS; ipi++) {
if ((irq = per_cpu(ipi_to_irq, cpu)[ipi]) == -1)
continue;
BUG_ON(irq_info[irq].type != IRQT_IPI);
BUG_ON(irq_info[irq].index != ipi);
/* Get a new binding from Xen. */
bind_ipi.vcpu = cpu;
if (HYPERVISOR_event_channel_op(EVTCHNOP_bind_ipi,
&bind_ipi) != 0)
BUG();
evtchn = bind_ipi.port;
/* Record the new mapping. */
evtchn_to_irq[evtchn] = irq;
irq_info[irq] = mk_irq_info(IRQT_IPI, ipi, evtchn);
bind_evtchn_to_cpu(evtchn, cpu);
/* Ready for use. */
unmask_evtchn(evtchn);
}
}
void xen_irq_resume(void)
{
unsigned int cpu, irq, evtchn;
init_evtchn_cpu_bindings();
/* New event-channel space is not 'live' yet. */
for (evtchn = 0; evtchn < NR_EVENT_CHANNELS; evtchn++)
mask_evtchn(evtchn);
/* No IRQ <-> event-channel mappings. */
for (irq = 0; irq < NR_IRQS; irq++)
irq_info[irq].evtchn = 0; /* zap event-channel binding */
for (evtchn = 0; evtchn < NR_EVENT_CHANNELS; evtchn++)
evtchn_to_irq[evtchn] = -1;
for_each_possible_cpu(cpu) {
restore_cpu_virqs(cpu);
restore_cpu_ipis(cpu);
}
}
static struct irq_chip xen_dynamic_chip __read_mostly = {
.name = "xen-dyn",
.mask = disable_dynirq,

View file

@ -471,14 +471,14 @@ static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
return 0;
}
static int gnttab_resume(void)
int gnttab_resume(void)
{
if (max_nr_grant_frames() < nr_grant_frames)
return -ENOSYS;
return gnttab_map(0, nr_grant_frames - 1);
}
static int gnttab_suspend(void)
int gnttab_suspend(void)
{
arch_gnttab_unmap_shared(shared, nr_grant_frames);
return 0;

View file

@ -5,21 +5,113 @@
#include <linux/err.h>
#include <linux/reboot.h>
#include <linux/sysrq.h>
#include <linux/stop_machine.h>
#include <linux/freezer.h>
#include <xen/xenbus.h>
#include <xen/grant_table.h>
#include <xen/events.h>
#include <xen/hvc-console.h>
#include <xen/xen-ops.h>
#define SHUTDOWN_INVALID -1
#define SHUTDOWN_POWEROFF 0
#define SHUTDOWN_SUSPEND 2
/* Code 3 is SHUTDOWN_CRASH, which we don't use because the domain can only
* report a crash, not be instructed to crash!
* HALT is the same as POWEROFF, as far as we're concerned. The tools use
* the distinction when we return the reason code to them.
*/
#define SHUTDOWN_HALT 4
#include <asm/xen/hypercall.h>
#include <asm/xen/page.h>
enum shutdown_state {
SHUTDOWN_INVALID = -1,
SHUTDOWN_POWEROFF = 0,
SHUTDOWN_SUSPEND = 2,
/* Code 3 is SHUTDOWN_CRASH, which we don't use because the domain can only
report a crash, not be instructed to crash!
HALT is the same as POWEROFF, as far as we're concerned. The tools use
the distinction when we return the reason code to them. */
SHUTDOWN_HALT = 4,
};
/* Ignore multiple shutdown requests. */
static int shutting_down = SHUTDOWN_INVALID;
static enum shutdown_state shutting_down = SHUTDOWN_INVALID;
static int xen_suspend(void *data)
{
int *cancelled = data;
BUG_ON(!irqs_disabled());
load_cr3(swapper_pg_dir);
xen_mm_pin_all();
gnttab_suspend();
xen_time_suspend();
xen_pre_suspend();
/*
* This hypercall returns 1 if suspend was cancelled
* or the domain was merely checkpointed, and 0 if it
* is resuming in a new domain.
*/
*cancelled = HYPERVISOR_suspend(virt_to_mfn(xen_start_info));
xen_post_suspend(*cancelled);
xen_time_resume();
gnttab_resume();
xen_mm_unpin_all();
if (!*cancelled) {
xen_irq_resume();
xen_console_resume();
}
return 0;
}
static void do_suspend(void)
{
int err;
int cancelled = 1;
shutting_down = SHUTDOWN_SUSPEND;
#ifdef CONFIG_PREEMPT
/* If the kernel is preemptible, we need to freeze all the processes
to prevent them from being in the middle of a pagetable update
during suspend. */
err = freeze_processes();
if (err) {
printk(KERN_ERR "xen suspend: freeze failed %d\n", err);
return;
}
#endif
err = device_suspend(PMSG_SUSPEND);
if (err) {
printk(KERN_ERR "xen suspend: device_suspend %d\n", err);
goto out;
}
printk("suspending xenbus...\n");
/* XXX use normal device tree? */
xenbus_suspend();
err = stop_machine_run(xen_suspend, &cancelled, 0);
if (err) {
printk(KERN_ERR "failed to start xen_suspend: %d\n", err);
goto out;
}
if (!cancelled)
xenbus_resume();
else
xenbus_suspend_cancel();
device_resume();
out:
#ifdef CONFIG_PREEMPT
thaw_processes();
#endif
shutting_down = SHUTDOWN_INVALID;
}
static void shutdown_handler(struct xenbus_watch *watch,
const char **vec, unsigned int len)
@ -52,11 +144,17 @@ static void shutdown_handler(struct xenbus_watch *watch,
}
if (strcmp(str, "poweroff") == 0 ||
strcmp(str, "halt") == 0)
strcmp(str, "halt") == 0) {
shutting_down = SHUTDOWN_POWEROFF;
orderly_poweroff(false);
else if (strcmp(str, "reboot") == 0)
} else if (strcmp(str, "reboot") == 0) {
shutting_down = SHUTDOWN_POWEROFF; /* ? */
ctrl_alt_del();
else {
#ifdef CONFIG_PM_SLEEP
} else if (strcmp(str, "suspend") == 0) {
do_suspend();
#endif
} else {
printk(KERN_INFO "Ignoring shutdown request: %s\n", str);
shutting_down = SHUTDOWN_INVALID;
}

View file

@ -157,6 +157,7 @@ PAGEFLAG(Active, active) __CLEARPAGEFLAG(Active, active)
__PAGEFLAG(Slab, slab)
PAGEFLAG(Checked, owner_priv_1) /* Used by some filesystems */
PAGEFLAG(Pinned, owner_priv_1) TESTSCFLAG(Pinned, owner_priv_1) /* Xen */
PAGEFLAG(SavePinned, dirty); /* Xen */
PAGEFLAG(Reserved, reserved) __CLEARPAGEFLAG(Reserved, reserved)
PAGEFLAG(Private, private) __CLEARPAGEFLAG(Private, private)
__SETPAGEFLAG(Private, private)

View file

@ -41,4 +41,7 @@ static inline void notify_remote_via_evtchn(int port)
}
extern void notify_remote_via_irq(int irq);
extern void xen_irq_resume(void);
#endif /* _XEN_EVENTS_H */

View file

@ -51,6 +51,9 @@ struct gnttab_free_callback {
u16 count;
};
int gnttab_suspend(void);
int gnttab_resume(void);
int gnttab_grant_foreign_access(domid_t domid, unsigned long frame,
int readonly);

View file

@ -5,4 +5,13 @@
DECLARE_PER_CPU(struct vcpu_info *, xen_vcpu);
void xen_pre_suspend(void);
void xen_post_suspend(int suspend_cancelled);
void xen_mm_pin_all(void);
void xen_mm_unpin_all(void);
void xen_time_suspend(void);
void xen_time_resume(void);
#endif /* INCLUDE_XEN_OPS_H */