C++ pfn_to_mfn函数代码示例

static void xen_load_gdt(const struct desc_ptr *dtr)
{
	unsigned long va = dtr->address;
	unsigned int size = dtr->size + 1;
	unsigned pages = (size + PAGE_SIZE - 1) / PAGE_SIZE;
	unsigned long frames[pages];
	int f;

	/*
	 * A GDT can be up to 64k in size, which corresponds to 8192
	 * 8-byte entries, or 16 4k pages..
	 */

	BUG_ON(size > 65536);
	BUG_ON(va & ~PAGE_MASK);

	for (f = 0; va < dtr->address + size; va += PAGE_SIZE, f++) {
		int level;
		pte_t *ptep;
		unsigned long pfn, mfn;
		void *virt;

		/*
		 * The GDT is per-cpu and is in the percpu data area.
		 * That can be virtually mapped, so we need to do a
		 * page-walk to get the underlying MFN for the
		 * hypercall.  The page can also be in the kernel's
		 * linear range, so we need to RO that mapping too.
		 */
		ptep = lookup_address(va, &level);
		BUG_ON(ptep == NULL);

		pfn = pte_pfn(*ptep);
		mfn = pfn_to_mfn(pfn);
		virt = __va(PFN_PHYS(pfn));

		frames[f] = mfn;

		make_lowmem_page_readonly((void *)va);
		make_lowmem_page_readonly(virt);
	}

	if (HYPERVISOR_set_gdt(frames, size / sizeof(struct desc_struct)))
		BUG();
}

static void xen_load_gdt(const struct desc_ptr *dtr)
{
	unsigned long va = dtr->address;
	unsigned int size = dtr->size + 1;
	unsigned pages = (size + PAGE_SIZE - 1) / PAGE_SIZE;
	unsigned long frames[pages];
	int f;

	/*
                                                             
                                    
  */

	BUG_ON(size > 65536);
	BUG_ON(va & ~PAGE_MASK);

	for (f = 0; va < dtr->address + size; va += PAGE_SIZE, f++) {
		int level;
		pte_t *ptep;
		unsigned long pfn, mfn;
		void *virt;

		/*
                                                       
                                                     
                                                
                                                     
                                                     
   */
		ptep = lookup_address(va, &level);
		BUG_ON(ptep == NULL);

		pfn = pte_pfn(*ptep);
		mfn = pfn_to_mfn(pfn);
		virt = __va(PFN_PHYS(pfn));

		frames[f] = mfn;

		make_lowmem_page_readonly((void *)va);
		make_lowmem_page_readonly(virt);
	}

	if (HYPERVISOR_set_gdt(frames, size / sizeof(struct desc_struct)))
		BUG();
}

void clear_highpage(struct page *page)
{
	void *kaddr;

	if (likely(xen_feature(XENFEAT_highmem_assist))
	    && PageHighMem(page)) {
		struct mmuext_op meo;

		meo.cmd = MMUEXT_CLEAR_PAGE;
		meo.arg1.mfn = pfn_to_mfn(page_to_pfn(page));
		if (HYPERVISOR_mmuext_op(&meo, 1, NULL, DOMID_SELF) == 0)
			return;
	}

	kaddr = kmap_atomic(page, KM_USER0);
	clear_page(kaddr);
	kunmap_atomic(kaddr, KM_USER0);
}

int set_foreign_p2m_mapping(struct gnttab_map_grant_ref *map_ops,
			    struct gnttab_map_grant_ref *kmap_ops,
			    struct page **pages, unsigned int count)
{
	int i, ret = 0;
	pte_t *pte;

	if (xen_feature(XENFEAT_auto_translated_physmap))
		return 0;

	if (kmap_ops) {
		ret = HYPERVISOR_grant_table_op(GNTTABOP_map_grant_ref,
						kmap_ops, count);
		if (ret)
			goto out;
	}

	for (i = 0; i < count; i++) {
		unsigned long mfn, pfn;

		/* Do not add to override if the map failed. */
		if (map_ops[i].status)
			continue;

		if (map_ops[i].flags & GNTMAP_contains_pte) {
			pte = (pte_t *)(mfn_to_virt(PFN_DOWN(map_ops[i].host_addr)) +
				(map_ops[i].host_addr & ~PAGE_MASK));
			mfn = pte_mfn(*pte);
		} else {
			mfn = PFN_DOWN(map_ops[i].dev_bus_addr);
		}
		pfn = page_to_pfn(pages[i]);

		WARN(pfn_to_mfn(pfn) != INVALID_P2M_ENTRY, "page must be ballooned");

		if (unlikely(!set_phys_to_machine(pfn, FOREIGN_FRAME(mfn)))) {
			ret = -ENOMEM;
			goto out;
		}
	}

out:
	return ret;
}

/* Release a pagetables pages back as normal RW */
static void xen_pgd_unpin(pgd_t *pgd)
{
	struct mmuext_op *op;
	struct multicall_space mcs;

	xen_mc_batch();

	mcs = __xen_mc_entry(sizeof(*op));

	op = mcs.args;
	op->cmd = MMUEXT_UNPIN_TABLE;
	op->arg1.mfn = pfn_to_mfn(PFN_DOWN(__pa(pgd)));

	MULTI_mmuext_op(mcs.mc, op, 1, NULL, DOMID_SELF);

	pgd_walk(pgd, unpin_page, TASK_SIZE);

	xen_mc_issue(0);
}

int kexec_allocate(struct xc_dom_image *dom, xen_vaddr_t up_to)
{
    unsigned long new_allocated = (up_to - dom->parms.virt_base) / PAGE_SIZE;
    unsigned long i;

    pages = realloc(pages, new_allocated * sizeof(*pages));
    pages_mfns = realloc(pages_mfns, new_allocated * sizeof(*pages_mfns));
    pages_moved2pfns = realloc(pages_moved2pfns, new_allocated * sizeof(*pages_moved2pfns));
    for (i = allocated; i < new_allocated; i++) {
        /* Exchange old page of PFN i with a newly allocated page.  */
        xen_pfn_t old_mfn = dom->p2m_host[i];
        xen_pfn_t new_pfn;
        xen_pfn_t new_mfn;

        pages[i] = alloc_page();
        memset((void*) pages[i], 0, PAGE_SIZE);
        new_pfn = PHYS_PFN(to_phys(pages[i]));
        pages_mfns[i] = new_mfn = pfn_to_mfn(new_pfn);

	/*
	 * If PFN of newly allocated page (new_pfn) is less then currently
	 * requested PFN (i) then look for relevant PFN/MFN pair. In this
	 * situation dom->p2m_host[new_pfn] no longer contains proper MFN
	 * because original page with new_pfn was moved earlier
	 * to different location.
	 */
	for (; new_pfn < i; new_pfn = pages_moved2pfns[new_pfn]);

	/* Store destination PFN of currently requested page. */
	pages_moved2pfns[i] = new_pfn;

        /* Put old page at new PFN */
        dom->p2m_host[new_pfn] = old_mfn;

        /* Put new page at PFN i */
        dom->p2m_host[i] = new_mfn;
    }

    allocated = new_allocated;

    return 0;
}

void build_pagetable(unsigned long *start_pfn, unsigned long *max_pfn)
{
    unsigned long start_address, end_address;
    unsigned long pfn_to_map, pt_pfn = *start_pfn;
    static mmu_update_t mmu_updates[L1_PAGETABLE_ENTRIES + 1];
    pgentry_t *tab = (pgentry_t *)start_info.pt_base, page;
    unsigned long mfn = pfn_to_mfn(virt_to_pfn(start_info.pt_base));
    unsigned long offset;
    int count = 0;

    pfn_to_map = (start_info.nr_pt_frames - NOT_L1_FRAMES) * L1_PAGETABLE_ENTRIES;

    if (*max_pfn >= virt_to_pfn(HYPERVISOR_VIRT_START))
    {
        printk("WARNING: Mini-OS trying to use Xen virtual space. "
               "Truncating memory from %dMB to ",
               ((unsigned long)pfn_to_virt(*max_pfn) - (unsigned long)&_text)>>20);
        *max_pfn = virt_to_pfn(HYPERVISOR_VIRT_START - PAGE_SIZE);
        printk("%dMB\n",
               ((unsigned long)pfn_to_virt(*max_pfn) - (unsigned long)&_text)>>20);
    }

static void __init xen_add_extra_mem(u64 start, u64 size)
{
	unsigned long pfn;
	int i;

	for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
		/* Add new region. */
		if (xen_extra_mem[i].size == 0) {
			xen_extra_mem[i].start = start;
			xen_extra_mem[i].size  = size;
			break;
		}
		/* Append to existing region. */
		if (xen_extra_mem[i].start + xen_extra_mem[i].size == start) {
			xen_extra_mem[i].size += size;
			break;
		}
	}
	if (i == XEN_EXTRA_MEM_MAX_REGIONS)
		printk(KERN_WARNING "Warning: not enough extra memory regions\n");

	memblock_reserve(start, size);

	if (xen_feature(XENFEAT_auto_translated_physmap))
		return;

	xen_max_p2m_pfn = PFN_DOWN(start + size);
	for (pfn = PFN_DOWN(start); pfn < xen_max_p2m_pfn; pfn++) {
		unsigned long mfn = pfn_to_mfn(pfn);

		if (WARN(mfn == pfn, "Trying to over-write 1-1 mapping (pfn: %lx)\n", pfn))
			continue;
		WARN(mfn != INVALID_P2M_ENTRY, "Trying to remove %lx which has %lx mfn!\n",
			pfn, mfn);

		__set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
	}
}

static unsigned long __init xen_release_chunk(unsigned long start,
					      unsigned long end)
{
	struct xen_memory_reservation reservation = {
		.address_bits = 0,
		.extent_order = 0,
		.domid        = DOMID_SELF
	};
	unsigned long len = 0;
	unsigned long pfn;
	int ret;

	for(pfn = start; pfn < end; pfn++) {
		unsigned long mfn = pfn_to_mfn(pfn);

		/* Make sure pfn exists to start with */
		if (mfn == INVALID_P2M_ENTRY || mfn_to_pfn(mfn) != pfn)
			continue;

		set_xen_guest_handle(reservation.extent_start, &mfn);
		reservation.nr_extents = 1;

		ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation,
					   &reservation);
		WARN(ret != 1, "Failed to release pfn %lx err=%d\n", pfn, ret);
		if (ret == 1) {
			__set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
			len++;
		}
	}
	printk(KERN_INFO "Freeing  %lx-%lx pfn range: %lu pages freed\n",
	       start, end, len);

	return len;
}

static unsigned long __init xen_set_identity_and_release(
	const struct e820entry *list, size_t map_size, unsigned long nr_pages)
{
	phys_addr_t start = 0;
	unsigned long released = 0;
	unsigned long identity = 0;
	const struct e820entry *entry;
	int i;

	/*
	 * Combine non-RAM regions and gaps until a RAM region (or the
	 * end of the map) is reached, then set the 1:1 map and
	 * release the pages (if available) in those non-RAM regions.
	 *
	 * The combined non-RAM regions are rounded to a whole number
	 * of pages so any partial pages are accessible via the 1:1
	 * mapping.  This is needed for some BIOSes that put (for
	 * example) the DMI tables in a reserved region that begins on
	 * a non-page boundary.
	 */
	for (i = 0, entry = list; i < map_size; i++, entry++) {
		phys_addr_t end = entry->addr + entry->size;

		if (entry->type == E820_RAM || i == map_size - 1) {
			unsigned long start_pfn = PFN_DOWN(start);
			unsigned long end_pfn = PFN_UP(end);

			if (entry->type == E820_RAM)
				end_pfn = PFN_UP(entry->addr);

			if (start_pfn < end_pfn) {
				if (start_pfn < nr_pages)
					released += xen_release_chunk(
						start_pfn, min(end_pfn, nr_pages));

				identity += set_phys_range_identity(
					start_pfn, end_pfn);
			}
			start = end;
		}
	}

	printk(KERN_INFO "Released %lu pages of unused memory\n", released);
	printk(KERN_INFO "Set %ld page(s) to 1-1 mapping\n", identity);

	return released;
}

void free_pmd_page(unsigned long addr)
{
    struct ptrpmd *newstruct = NULL;
    struct ptrpmd *temp_head = NULL;
    int i = 0;
    int counter = 0;
    
    newstruct = (struct ptrpmd *)kmalloc(sizeof(struct ptrpmd), GFP_KERNEL);
    newstruct -> content = addr;

    spin_lock(&pmd_cache_lock);
    newstruct -> next = pmd_head;
    pmd_head = newstruct;
    temp_head = pmd_head;
    
    /*free node */
    if(pmd_used_counter)
    	pmd_used_counter--;
    pmd_free_counter++;
   
    if(pmd_used_counter) 
    {
	//if((pmd_free_counter/pmd_used_counter>=3) && ((pmd_used_counter + pmd_free_counter) >= 1800))
    	//if((pmd_used_counter/pmd_free_counter < 8) && ((pmd_used_counter + pmd_free_counter) >= 600))
    	//if((pmd_used_counter/pmd_free_counter < 1) && (pmd_used_counter >= 42))
    	//if((pmd_free_counter/pmd_used_counter >= 4) && (pmd_used_counter >= 80))
    	//if((pmd_free_counter/pmd_used_counter >= 6) && ((pgd_used_counter + pgd_free_counter) >= 230))
    	//if((pmd_used_counter/pmd_free_counter < 2) && ((pgd_used_counter + pgd_free_counter) >= 80))
    	if((pmd_free_counter/pmd_used_counter > 1) && ((pmd_used_counter + pmd_free_counter) >= 40))
    	//if((pmd_free_counter/pmd_used_counter >= 5) && ((pmd_used_counter + pmd_free_counter) >= 200))
    	{
        	//counter = pmd_free_counter * 3 / 10;
        	counter = 0;
       		for(i=0;i<counter;i++)
		{
	    		pmd_head = pmd_head->next;
		}
        	pmd_free_counter -= counter;
    	}
    }
    spin_unlock(&pmd_cache_lock);

    if(counter != 0)
    {
    	struct ptrpmd * newstructarray = NULL;
    	struct ptrpmd * newstructarray_head = NULL;
    	int rc = 1;
    	newstructarray = (struct ptrpmd *)kmalloc(sizeof(struct ptrpmd) * counter, GFP_KERNEL);
    	newstructarray_head = newstructarray;
        for (i=0;i<counter;i++)
        {
	    newstruct = temp_head;
	    temp_head = temp_head->next;
	    newstructarray[i].content = pfn_to_mfn(PFN_DOWN(__pa(newstruct->content)));
	    kfree(newstruct);
        }
	//hypercall newstructarray
	rc = HYPERVISOR_pmd_op(newstructarray, counter);
        //if (rc == 0)
 	    //printk("pmd cache free success\n");
	//else 
 	    //printk("pmd cache free error\n");
	    
	//free page to the buddy system
        newstructarray = newstructarray_head;
	for(i=0;i<counter;i++)
	{
	    free_page(newstructarray[i].content);
	}

	//free newstructarray
	kfree(newstructarray);
    }
    
    return;
}

static int map_data_for_request(struct vscsifrnt_info *info,
				struct scsi_cmnd *sc,
				struct vscsiif_request *ring_req,
				struct vscsifrnt_shadow *shadow)
{
	grant_ref_t gref_head;
	struct page *page;
	int err, ref, ref_cnt = 0;
	int grant_ro = (sc->sc_data_direction == DMA_TO_DEVICE);
	unsigned int i, off, len, bytes;
	unsigned int data_len = scsi_bufflen(sc);
	unsigned int data_grants = 0, seg_grants = 0;
	struct scatterlist *sg;
	unsigned long mfn;
	struct scsiif_request_segment *seg;

	ring_req->nr_segments = 0;
	if (sc->sc_data_direction == DMA_NONE || !data_len)
		return 0;

	scsi_for_each_sg(sc, sg, scsi_sg_count(sc), i)
		data_grants += PFN_UP(sg->offset + sg->length);

	if (data_grants > VSCSIIF_SG_TABLESIZE) {
		if (data_grants > info->host->sg_tablesize) {
			shost_printk(KERN_ERR, info->host, KBUILD_MODNAME
			     "Unable to map request_buffer for command!\n");
			return -E2BIG;
		}
		seg_grants = vscsiif_grants_sg(data_grants);
		shadow->sg = kcalloc(data_grants,
			sizeof(struct scsiif_request_segment), GFP_ATOMIC);
		if (!shadow->sg)
			return -ENOMEM;
	}
	seg = shadow->sg ? : ring_req->seg;

	err = gnttab_alloc_grant_references(seg_grants + data_grants,
					    &gref_head);
	if (err) {
		kfree(shadow->sg);
		shost_printk(KERN_ERR, info->host, KBUILD_MODNAME
			     "gnttab_alloc_grant_references() error\n");
		return -ENOMEM;
	}

	if (seg_grants) {
		page = virt_to_page(seg);
		off = (unsigned long)seg & ~PAGE_MASK;
		len = sizeof(struct scsiif_request_segment) * data_grants;
		while (len > 0) {
			bytes = min_t(unsigned int, len, PAGE_SIZE - off);

			ref = gnttab_claim_grant_reference(&gref_head);
			BUG_ON(ref == -ENOSPC);

			mfn = pfn_to_mfn(page_to_pfn(page));
			gnttab_grant_foreign_access_ref(ref,
				info->dev->otherend_id, mfn, 1);
			shadow->gref[ref_cnt] = ref;
			ring_req->seg[ref_cnt].gref   = ref;
			ring_req->seg[ref_cnt].offset = (uint16_t)off;
			ring_req->seg[ref_cnt].length = (uint16_t)bytes;

			page++;
			len -= bytes;
			off = 0;
			ref_cnt++;
		}
		BUG_ON(seg_grants < ref_cnt);
		seg_grants = ref_cnt;
	}

	scsi_for_each_sg(sc, sg, scsi_sg_count(sc), i) {
		page = sg_page(sg);
		off = sg->offset;
		len = sg->length;

		while (len > 0 && data_len > 0) {
			/*
			 * sg sends a scatterlist that is larger than
			 * the data_len it wants transferred for certain
			 * IO sizes.
			 */
			bytes = min_t(unsigned int, len, PAGE_SIZE - off);
			bytes = min(bytes, data_len);

			ref = gnttab_claim_grant_reference(&gref_head);
			BUG_ON(ref == -ENOSPC);

			mfn = pfn_to_mfn(page_to_pfn(page));
			gnttab_grant_foreign_access_ref(ref,
				info->dev->otherend_id, mfn, grant_ro);

			shadow->gref[ref_cnt] = ref;
			seg->gref   = ref;
			seg->offset = (uint16_t)off;
			seg->length = (uint16_t)bytes;

			page++;
//.........这里部分代码省略.........

static unsigned long __init xen_do_chunk(unsigned long start,
					 unsigned long end, bool release)
{
	struct xen_memory_reservation reservation = {
		.address_bits = 0,
		.extent_order = 0,
		.domid        = DOMID_SELF
	};
	unsigned long len = 0;
	int xlated_phys = xen_feature(XENFEAT_auto_translated_physmap);
	unsigned long pfn;
	int ret;

	for (pfn = start; pfn < end; pfn++) {
		unsigned long frame;
		unsigned long mfn = pfn_to_mfn(pfn);

		if (release) {
			/* Make sure pfn exists to start with */
			if (mfn == INVALID_P2M_ENTRY || mfn_to_pfn(mfn) != pfn)
				continue;
			frame = mfn;
		} else {
			if (!xlated_phys && mfn != INVALID_P2M_ENTRY)
				continue;
			frame = pfn;
		}
		set_xen_guest_handle(reservation.extent_start, &frame);
		reservation.nr_extents = 1;

		ret = HYPERVISOR_memory_op(release ? XENMEM_decrease_reservation : XENMEM_populate_physmap,
					   &reservation);
		WARN(ret != 1, "Failed to %s pfn %lx err=%d\n",
		     release ? "release" : "populate", pfn, ret);

		if (ret == 1) {
			if (!early_set_phys_to_machine(pfn, release ? INVALID_P2M_ENTRY : frame)) {
				if (release)
					break;
				set_xen_guest_handle(reservation.extent_start, &frame);
				reservation.nr_extents = 1;
				ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation,
							   &reservation);
				break;
			}
			len++;
		} else
			break;
	}
	if (len)
		printk(KERN_INFO "%s %lx-%lx pfn range: %lu pages %s\n",
		       release ? "Freeing" : "Populating",
		       start, end, len,
		       release ? "freed" : "added");

	return len;
}

static unsigned long __init xen_release_chunk(unsigned long start,
					      unsigned long end)
{
	/*
	 * Xen already ballooned out the E820 non RAM regions for us
	 * and set them up properly in EPT.
	 */
	if (xen_feature(XENFEAT_auto_translated_physmap))
		return end - start;

	return xen_do_chunk(start, end, true);
}

static unsigned long __init xen_populate_chunk(
	const struct e820entry *list, size_t map_size,
	unsigned long max_pfn, unsigned long *last_pfn,
	unsigned long credits_left)
{
	const struct e820entry *entry;
	unsigned int i;
	unsigned long done = 0;
	unsigned long dest_pfn;

	for (i = 0, entry = list; i < map_size; i++, entry++) {
		unsigned long s_pfn;
		unsigned long e_pfn;
		unsigned long pfns;
		long capacity;

		if (credits_left <= 0)
			break;

		if (entry->type != E820_RAM)
			continue;

		e_pfn = PFN_DOWN(entry->addr + entry->size);

		/* We only care about E820 after the xen_start_info->nr_pages */
		if (e_pfn <= max_pfn)
			continue;

		s_pfn = PFN_UP(entry->addr);
//.........这里部分代码省略.........

/*
 * Top level routine to direct suspend/resume of a domain.
 */
void
xen_suspend_domain(void)
{
	extern void rtcsync(void);
	extern hrtime_t hres_last_tick;
	mfn_t start_info_mfn;
	ulong_t flags;
	pfn_t pfn;
	int i;

	/*
	 * Check that we are happy to suspend on this hypervisor.
	 */
	if (xen_hypervisor_supports_solaris(XEN_SUSPEND_CHECK) == 0) {
		cpr_err(CE_WARN, "Cannot suspend on this hypervisor "
		    "version: v%lu.%lu%s, need at least version v3.0.4 or "
		    "-xvm based hypervisor", XENVER_CURRENT(xv_major),
		    XENVER_CURRENT(xv_minor), XENVER_CURRENT(xv_ver));
		return;
	}

	/*
	 * XXPV - Are we definitely OK to suspend by the time we've connected
	 * the handler?
	 */

	cpr_err(CE_NOTE, "Domain suspending for save/migrate");

	SUSPEND_DEBUG("xen_suspend_domain\n");

	/*
	 * suspend interrupts and devices
	 * XXPV - we use suspend/resume for both save/restore domains (like sun
	 * cpr) and for migration.  Would be nice to know the difference if
	 * possible.  For save/restore where down time may be a long time, we
	 * may want to do more of the things that cpr does.  (i.e. notify user
	 * processes, shrink memory footprint for faster restore, etc.)
	 */
	xen_suspend_devices();
	SUSPEND_DEBUG("xenbus_suspend\n");
	xenbus_suspend();

	pfn = hat_getpfnum(kas.a_hat, (caddr_t)xen_info);
	start_info_mfn = pfn_to_mfn(pfn);

	/*
	 * XXPV: cpu hotplug can hold this under a xenbus watch. Are we safe
	 * wrt xenbus being suspended here?
	 */
	mutex_enter(&cpu_lock);

	/*
	 * Suspend must be done on vcpu 0, as no context for other CPUs is
	 * saved.
	 *
	 * XXPV - add to taskq API ?
	 */
	thread_affinity_set(curthread, 0);
	kpreempt_disable();

	SUSPEND_DEBUG("xen_start_migrate\n");
	xen_start_migrate();
	if (ncpus > 1)
		suspend_cpus();

	/*
	 * We can grab the ec_lock as it's a spinlock with a high SPL. Hence
	 * any holder would have dropped it to get through suspend_cpus().
	 */
	mutex_enter(&ec_lock);

	/*
	 * From here on in, we can't take locks.
	 */
	SUSPEND_DEBUG("ec_suspend\n");
	ec_suspend();
	SUSPEND_DEBUG("gnttab_suspend\n");
	gnttab_suspend();

	flags = intr_clear();

	xpv_time_suspend();

	/*
	 * Currently, the hypervisor incorrectly fails to bring back
	 * powered-down VCPUs.  Thus we need to record any powered-down VCPUs
	 * to prevent any attempts to operate on them.  But we have to do this
	 * *after* the very first time we do ec_suspend().
	 */
	for (i = 1; i < ncpus; i++) {
		if (cpu[i] == NULL)
			continue;

		if (cpu_get_state(cpu[i]) == P_POWEROFF)
			CPUSET_ATOMIC_ADD(cpu_suspend_lost_set, i);
	}

//.........这里部分代码省略.........

static void xennet_alloc_rx_buffers(struct net_device *dev)
{
	unsigned short id;
	struct netfront_info *np = netdev_priv(dev);
	struct sk_buff *skb;
	struct page *page;
	int i, batch_target, notify;
	RING_IDX req_prod = np->rx.req_prod_pvt;
	grant_ref_t ref;
	unsigned long pfn;
	void *vaddr;
	struct xen_netif_rx_request *req;

	if (unlikely(!netif_carrier_ok(dev)))
		return;

	/*
	 * Allocate skbuffs greedily, even though we batch updates to the
	 * receive ring. This creates a less bursty demand on the memory
	 * allocator, so should reduce the chance of failed allocation requests
	 * both for ourself and for other kernel subsystems.
	 */
	batch_target = np->rx_target - (req_prod - np->rx.rsp_cons);
	for (i = skb_queue_len(&np->rx_batch); i < batch_target; i++) {
		skb = __netdev_alloc_skb(dev, RX_COPY_THRESHOLD,
					 GFP_ATOMIC | __GFP_NOWARN);
		if (unlikely(!skb))
			goto no_skb;

		page = alloc_page(GFP_ATOMIC | __GFP_NOWARN);
		if (!page) {
			kfree_skb(skb);
no_skb:
			/* Any skbuffs queued for refill? Force them out. */
			if (i != 0)
				goto refill;
			/* Could not allocate any skbuffs. Try again later. */
			mod_timer(&np->rx_refill_timer,
				  jiffies + (HZ/10));
			break;
		}

		skb_shinfo(skb)->frags[0].page = page;
		skb_shinfo(skb)->nr_frags = 1;
		__skb_queue_tail(&np->rx_batch, skb);
	}

	/* Is the batch large enough to be worthwhile? */
	if (i < (np->rx_target/2)) {
		if (req_prod > np->rx.sring->req_prod)
			goto push;
		return;
	}

	/* Adjust our fill target if we risked running out of buffers. */
	if (((req_prod - np->rx.sring->rsp_prod) < (np->rx_target / 4)) &&
	    ((np->rx_target *= 2) > np->rx_max_target))
		np->rx_target = np->rx_max_target;

 refill:
	for (i = 0; ; i++) {
		skb = __skb_dequeue(&np->rx_batch);
		if (skb == NULL)
			break;

		skb->dev = dev;

		id = xennet_rxidx(req_prod + i);

		BUG_ON(np->rx_skbs[id]);
		np->rx_skbs[id] = skb;

		ref = gnttab_claim_grant_reference(&np->gref_rx_head);
		BUG_ON((signed short)ref < 0);
		np->grant_rx_ref[id] = ref;

		pfn = page_to_pfn(skb_shinfo(skb)->frags[0].page);
		vaddr = page_address(skb_shinfo(skb)->frags[0].page);

		req = RING_GET_REQUEST(&np->rx, req_prod + i);
		gnttab_grant_foreign_access_ref(ref,
						np->xbdev->otherend_id,
						pfn_to_mfn(pfn),
						0);

		req->id = id;
		req->gref = ref;
	}

	wmb();		/* barrier so backend seens requests */

	/* Above is a suitable barrier to ensure backend will see requests. */
	np->rx.req_prod_pvt = req_prod + i;
 push:
	RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(&np->rx, notify);
	if (notify)
		notify_remote_via_irq(np->netdev->irq);
}

void kexec(void *kernel, long kernel_size, void *module, long module_size, char *cmdline, unsigned long flags)
{
    struct xc_dom_image *dom;
    int rc;
    domid_t domid = DOMID_SELF;
    xen_pfn_t pfn;
    xc_interface *xc_handle;
    unsigned long i;
    void *seg;
    xen_pfn_t boot_page_mfn = virt_to_mfn(&_boot_page);
    char features[] = "";
    struct mmu_update *m2p_updates;
    unsigned long nr_m2p_updates;

    DEBUG("booting with cmdline %s\n", cmdline);
    xc_handle = xc_interface_open(0,0,0);

    dom = xc_dom_allocate(xc_handle, cmdline, features);
    dom->allocate = kexec_allocate;

    /* We are using guest owned memory, therefore no limits. */
    xc_dom_kernel_max_size(dom, 0);
    xc_dom_ramdisk_max_size(dom, 0);

    dom->kernel_blob = kernel;
    dom->kernel_size = kernel_size;

    dom->ramdisk_blob = module;
    dom->ramdisk_size = module_size;

    dom->flags = flags;
    dom->console_evtchn = start_info.console.domU.evtchn;
    dom->xenstore_evtchn = start_info.store_evtchn;

    tpm_hash2pcr(dom, cmdline);

    if ( (rc = xc_dom_boot_xen_init(dom, xc_handle, domid)) != 0 ) {
        grub_printf("xc_dom_boot_xen_init returned %d\n", rc);
        errnum = ERR_BOOT_FAILURE;
        goto out;
    }
    if ( (rc = xc_dom_parse_image(dom)) != 0 ) {
        grub_printf("xc_dom_parse_image returned %d\n", rc);
        errnum = ERR_BOOT_FAILURE;
        goto out;
    }

#ifdef __i386__
    if (strcmp(dom->guest_type, "xen-3.0-x86_32p")) {
        grub_printf("can only boot x86 32 PAE kernels, not %s\n", dom->guest_type);
        errnum = ERR_EXEC_FORMAT;
        goto out;
    }
#endif
#ifdef __x86_64__
    if (strcmp(dom->guest_type, "xen-3.0-x86_64")) {
        grub_printf("can only boot x86 64 kernels, not %s\n", dom->guest_type);
        errnum = ERR_EXEC_FORMAT;
        goto out;
    }
#endif

    /* equivalent of xc_dom_mem_init */
    dom->arch_hooks = xc_dom_find_arch_hooks(xc_handle, dom->guest_type);
    dom->total_pages = start_info.nr_pages;

    /* equivalent of arch_setup_meminit */

    /* setup initial p2m */
    dom->p2m_host = malloc(sizeof(*dom->p2m_host) * dom->total_pages);

    /* Start with our current P2M */
    for (i = 0; i < dom->total_pages; i++)
        dom->p2m_host[i] = pfn_to_mfn(i);

    if ( (rc = xc_dom_build_image(dom)) != 0 ) {
        grub_printf("xc_dom_build_image returned %d\n", rc);
        errnum = ERR_BOOT_FAILURE;
        goto out;
    }

    /* copy hypercall page */
    /* TODO: domctl instead, but requires privileges */
    if (dom->parms.virt_hypercall != -1) {
        pfn = PHYS_PFN(dom->parms.virt_hypercall - dom->parms.virt_base);
        memcpy((void *) pages[pfn], hypercall_page, PAGE_SIZE);
    }

    /* Equivalent of xc_dom_boot_image */
    dom->shared_info_mfn = PHYS_PFN(start_info.shared_info);

    if (!xc_dom_compat_check(dom)) {
        grub_printf("xc_dom_compat_check failed\n");
        errnum = ERR_EXEC_FORMAT;
        goto out;
    }

    /* Move current console, xenstore and boot MFNs to the allocated place */
    do_exchange(dom, dom->console_pfn, start_info.console.domU.mfn);
    do_exchange(dom, dom->xenstore_pfn, start_info.store_mfn);
//.........这里部分代码省略.........