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Commit 0e91398f authored by Jeremy Fitzhardinge's avatar Jeremy Fitzhardinge Committed by Thomas Gleixner
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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: default avatarJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
parent 7d88d32a

arch/x86/xen/Makefile

+1 −1
Original line number Diff line number Diff line 
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

arch/x86/xen/enlighten.c

+3 −3
Original line number Diff line number Diff line
@@ -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;

arch/x86/xen/mmu.c

+46 −0
Original line number Diff line number Diff line
@@ -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);

arch/x86/xen/smp.c

+1 −1
Original line number Diff line number Diff line
@@ -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;

arch/x86/xen/suspend.c

0 → 100644
+42 −0
Original line number Diff line number Diff line 
#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();

}