text: // SPDX-License-Identifier: GPL-2.0
  /*
   * Machine specific setup for xen
   *
   * Jeremy Fitzhardinge <jeremy@xensource.com>, XenSource Inc, 2007
   */
  
  #include <linux/init.h>
  #include <linux/sched.h>
  #include <linux/mm.h>
  #include <linux/pm.h>
  #include <linux/memblock.h>
  #include <linux/cpuidle.h>
  #include <linux/cpufreq.h>
  #include <linux/memory_hotplug.h>
  
  #include <asm/elf.h>
  #include <asm/vdso.h>
  #include <asm/e820/api.h>
  #include <asm/setup.h>
  #include <asm/acpi.h>
  #include <asm/numa.h>
  #include <asm/idtentry.h>
  #include <asm/xen/hypervisor.h>
  #include <asm/xen/hypercall.h>
  
  #include <xen/xen.h>
  #include <xen/page.h>
  #include <xen/interface/callback.h>
  #include <xen/interface/memory.h>
  #include <xen/interface/physdev.h>
  #include <xen/features.h>
  #include <xen/hvc-console.h>
  #include "xen-ops.h"
  #include "vdso.h"
  #include "mmu.h"
  
  #define GB(x) ((uint64_t)(x) * 1024 * 1024 * 1024)
  
  /* Amount of extra memory space we add to the e820 ranges */
  struct xen_memory_region xen_extra_mem[XEN_EXTRA_MEM_MAX_REGIONS] __initdata;
  
  /* Number of pages released from the initial allocation. */
  unsigned long xen_released_pages;
  
  /* E820 map used during setting up memory. */
  static struct e820_table xen_e820_table __initdata;
  
  /*
   * Buffer used to remap identity mapped pages. We only need the virtual space.
   * The physical page behind this address is remapped as needed to different
   * buffer pages.
   */
  #define REMAP_SIZE	(P2M_PER_PAGE - 3)
  static struct {
  	unsigned long	next_area_mfn;
  	unsigned long	target_pfn;
  	unsigned long	size;
  	unsigned long	mfns[REMAP_SIZE];
  } xen_remap_buf __initdata __aligned(PAGE_SIZE);
  static unsigned long xen_remap_mfn __initdata = INVALID_P2M_ENTRY;
  
  /* 
   * The maximum amount of extra memory compared to the base size.  The
   * main scaling factor is the size of struct page.  At extreme ratios
   * of base:extra, all the base memory can be filled with page
   * structures for the extra memory, leaving no space for anything
   * else.
   * 
   * 10x seems like a reasonable balance between scaling flexibility and
   * leaving a practically usable system.
   */
  #define EXTRA_MEM_RATIO		(10)
  
  static bool xen_512gb_limit __initdata = IS_ENABLED(CONFIG_XEN_512GB);
  
  static void __init xen_parse_512gb(void)
  {
  	bool val = false;
  	char *arg;
  
  	arg = strstr(xen_start_info->cmd_line, "xen_512gb_limit");
  	if (!arg)
  		return;
  
  	arg = strstr(xen_start_info->cmd_line, "xen_512gb_limit=");
  	if (!arg)
  		val = true;
  	else if (strtobool(arg + strlen("xen_512gb_limit="), &val))
  		return;
  
  	xen_512gb_limit = val;
  }
  
  static void __init xen_add_extra_mem(unsigned long start_pfn,
  				     unsigned long n_pfns)
  {
  	int i;
  
  	/*
  	 * No need to check for zero size, should happen rarely and will only
  	 * write a new entry regarded to be unused due to zero size.
  	 */
  	for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
  		/* Add new region. */
  		if (xen_extra_mem[i].n_pfns == 0) {
  			xen_extra_mem[i].start_pfn = start_pfn;
  			xen_extra_mem[i].n_pfns = n_pfns;
  			break;
  		}
  		/* Append to existing region. */
  		if (xen_extra_mem[i].start_pfn + xen_extra_mem[i].n_pfns ==
  		    start_pfn) {
  			xen_extra_mem[i].n_pfns += n_pfns;
  			break;
  		}
  	}
  	if (i == XEN_EXTRA_MEM_MAX_REGIONS)
  		printk(KERN_WARNING "Warning: not enough extra memory regions\n");
  
  	memblock_reserve(PFN_PHYS(start_pfn), PFN_PHYS(n_pfns));
  }
  
  static void __init xen_del_extra_mem(unsigned long start_pfn,
  				     unsigned long n_pfns)
  {
  	int i;
  	unsigned long start_r, size_r;
  
  	for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
  		start_r = xen_extra_mem[i].start_pfn;
  		size_r = xen_extra_mem[i].n_pfns;
  
  		/* Start of region. */
  		if (start_r == start_pfn) {
  			BUG_ON(n_pfns > size_r);
  			xen_extra_mem[i].start_pfn += n_pfns;
  			xen_extra_mem[i].n_pfns -= n_pfns;
  			break;
  		}
  		/* End of region. */
  		if (start_r + size_r == start_pfn + n_pfns) {
  			BUG_ON(n_pfns > size_r);
  			xen_extra_mem[i].n_pfns -= n_pfns;
  			break;
  		}
  		/* Mid of region. */
  		if (start_pfn > start_r && start_pfn < start_r + size_r) {
  			BUG_ON(start_pfn + n_pfns > start_r + size_r);
  			xen_extra_mem[i].n_pfns = start_pfn - start_r;
  			/* Calling memblock_reserve() again is okay. */
  			xen_add_extra_mem(start_pfn + n_pfns, start_r + size_r -
  					  (start_pfn + n_pfns));
  			break;
  		}
  	}
  	memblock_free(PFN_PHYS(start_pfn), PFN_PHYS(n_pfns));
  }
  
  /*
   * Called during boot before the p2m list can take entries beyond the
   * hypervisor supplied p2m list. Entries in extra mem are to be regarded as
   * invalid.
   */
  unsigned long __ref xen_chk_extra_mem(unsigned long pfn)
  {
  	int i;
  
  	for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
  		if (pfn >= xen_extra_mem[i].start_pfn &&
  		    pfn < xen_extra_mem[i].start_pfn + xen_extra_mem[i].n_pfns)
  			return INVALID_P2M_ENTRY;
  	}
  
  	return IDENTITY_FRAME(pfn);
  }
  
  /*
   * Mark all pfns of extra mem as invalid in p2m list.
   */
  void __init xen_inv_extra_mem(void)
  {
  	unsigned long pfn, pfn_s, pfn_e;
  	int i;
  
  	for (i = 0; i < XEN_EXTRA_MEM_MAX_REGIONS; i++) {
  		if (!xen_extra_mem[i].n_pfns)
  			continue;
  		pfn_s = xen_extra_mem[i].start_pfn;
  		pfn_e = pfn_s + xen_extra_mem[i].n_pfns;
  		for (pfn = pfn_s; pfn < pfn_e; pfn++)
  			set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
  	}
  }
  
  /*
   * Finds the next RAM pfn available in the E820 map after min_pfn.
   * This function updates min_pfn with the pfn found and returns
   * the size of that range or zero if not found.
   */
  static unsigned long __init xen_find_pfn_range(unsigned long *min_pfn)
  {
  	const struct e820_entry *entry = xen_e820_table.entries;
  	unsigned int i;
  	unsigned long done = 0;
  
  	for (i = 0; i < xen_e820_table.nr_entries; i++, entry++) {
  		unsigned long s_pfn;
  		unsigned long e_pfn;
  
  		if (entry->type != E820_TYPE_RAM)
  			continue;
  
  		e_pfn = PFN_DOWN(entry->addr + entry->size);
  
  		/* We only care about E820 after this */
  		if (e_pfn <= *min_pfn)
  			continue;
  
  		s_pfn = PFN_UP(entry->addr);
  
  		/* If min_pfn falls within the E820 entry, we want to start
  		 * at the min_pfn PFN.
  		 */
  		if (s_pfn <= *min_pfn) {
  			done = e_pfn - *min_pfn;
  		} else {
  			done = e_pfn - s_pfn;
  			*min_pfn = s_pfn;
  		}
  		break;
  	}
  
  	return done;
  }
  
  static int __init xen_free_mfn(unsigned long mfn)
  {
  	struct xen_memory_reservation reservation = {
  		.address_bits = 0,
  		.extent_order = 0,
  		.domid        = DOMID_SELF
  	};
  
  	set_xen_guest_handle(reservation.extent_start, &mfn);
  	reservation.nr_extents = 1;
  
  	return HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation);
  }
  
  /*
   * This releases a chunk of memory and then does the identity map. It's used
   * as a fallback if the remapping fails.
   */
  static void __init xen_set_identity_and_release_chunk(unsigned long start_pfn,
  			unsigned long end_pfn, unsigned long nr_pages)
  {
  	unsigned long pfn, end;
  	int ret;
  
  	WARN_ON(start_pfn > end_pfn);
  
  	/* Release pages first. */
  	end = min(end_pfn, nr_pages);
  	for (pfn = start_pfn; 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;
  
  		ret = xen_free_mfn(mfn);
  		WARN(ret != 1, "Failed to release pfn %lx err=%d\n", pfn, ret);
  
  		if (ret == 1) {
  			xen_released_pages++;
  			if (!__set_phys_to_machine(pfn, INVALID_P2M_ENTRY))
  				break;
  		} else
  			break;
  	}
  
  	set_phys_range_identity(start_pfn, end_pfn);
  }
  
  /*
   * Helper function to update the p2m and m2p tables and kernel mapping.
   */
  static void __init xen_update_mem_tables(unsigned long pfn, unsigned long mfn)
  {
  	struct mmu_update update = {
  		.ptr = ((uint64_t)mfn << PAGE_SHIFT) | MMU_MACHPHYS_UPDATE,
  		.val = pfn
  	};
  
  	/* Update p2m */
  	if (!set_phys_to_machine(pfn, mfn)) {
  		WARN(1, "Failed to set p2m mapping for pfn=%ld mfn=%ld\n",
  		     pfn, mfn);
  		BUG();
  	}
  
  	/* Update m2p */
  	if (HYPERVISOR_mmu_update(&update, 1, NULL, DOMID_SELF) < 0) {
  		WARN(1, "Failed to set m2p mapping for mfn=%ld pfn=%ld\n",
  		     mfn, pfn);
  		BUG();
  	}
  
  	/* Update kernel mapping, but not for highmem. */
  	if (pfn >= PFN_UP(__pa(high_memory - 1)))
  		return;
  
  	if (HYPERVISOR_update_va_mapping((unsigned long)__va(pfn << PAGE_SHIFT),
  					 mfn_pte(mfn, PAGE_KERNEL), 0)) {
  		WARN(1, "Failed to update kernel mapping for mfn=%ld pfn=%ld\n",
  		      mfn, pfn);
  		BUG();
  	}
  }
  
  /*
   * This function updates the p2m and m2p tables with an identity map from
   * start_pfn to start_pfn+size and prepares remapping the underlying RAM of the
   * original allocation at remap_pfn. The information needed for remapping is
   * saved in the memory itself to avoid the need for allocating buffers. The
   * complete remap information is contained in a list of MFNs each containing
   * up to REMAP_SIZE MFNs and the start target PFN for doing the remap.
   * This enables us to preserve the original mfn sequence while doing the
   * remapping at a time when the memory management is capable of allocating
   * virtual and physical memory in arbitrary amounts, see 'xen_remap_memory' and
   * its callers.
   */
  static void __init xen_do_set_identity_and_remap_chunk(
          unsigned long start_pfn, unsigned long size, unsigned long remap_pfn)
  {
  	unsigned long buf = (unsigned long)&xen_remap_buf;
  	unsigned long mfn_save, mfn;
  	unsigned long ident_pfn_iter, remap_pfn_iter;
  	unsigned long ident_end_pfn = start_pfn + size;
  	unsigned long left = size;
  	unsigned int i, chunk;
  
  	WARN_ON(size == 0);
  
  	mfn_save = virt_to_mfn(buf);
  
  	for (ident_pfn_iter = start_pfn, remap_pfn_iter = remap_pfn;
  	     ident_pfn_iter < ident_end_pfn;
  	     ident_pfn_iter += REMAP_SIZE, remap_pfn_iter += REMAP_SIZE) {
  		chunk = (left < REMAP_SIZE) ? left : REMAP_SIZE;
  
  		/* Map first pfn to xen_remap_buf */
  		mfn = pfn_to_mfn(ident_pfn_iter);
  		set_pte_mfn(buf, mfn, PAGE_KERNEL);
  
  		/* Save mapping information in page */
  		xen_remap_buf.next_area_mfn = xen_remap_mfn;
  		xen_remap_buf.target_pfn = remap_pfn_iter;
  		xen_remap_buf.size = chunk;
  		for (i = 0; i < chunk; i++)
  			xen_remap_buf.mfns[i] = pfn_to_mfn(ident_pfn_iter + i);
  
  		/* Put remap buf into list. */
  		xen_remap_mfn = mfn;
  
  		/* Set identity map */
  		set_phys_range_identity(ident_pfn_iter, ident_pfn_iter + chunk);
  
  		left -= chunk;
  	}
  
  	/* Restore old xen_remap_buf mapping */
  	set_pte_mfn(buf, mfn_save, PAGE_KERNEL);
  }
  
  /*
   * This function takes a contiguous pfn range that needs to be identity mapped
   * and:
   *
   *  1) Finds a new range of pfns to use to remap based on E820 and remap_pfn.
   *  2) Calls the do_ function to actually do the mapping/remapping work.
   *
   * The goal is to not allocate additional memory but to remap the existing
   * pages. In the case of an error the underlying memory is simply released back
   * to Xen and not remapped.
   */
  static unsigned long __init xen_set_identity_and_remap_chunk(
  	unsigned long start_pfn, unsigned long end_pfn, unsigned long nr_pages,
  	unsigned long remap_pfn)
  {
  	unsigned long pfn;
  	unsigned long i = 0;
  	unsigned long n = end_pfn - start_pfn;
  
  	if (remap_pfn == 0)
  		remap_pfn = nr_pages;
  
  	while (i < n) {
  		unsigned long cur_pfn = start_pfn + i;
  		unsigned long left = n - i;
  		unsigned long size = left;
  		unsigned long remap_range_size;
  
  		/* Do not remap pages beyond the current allocation */
  		if (cur_pfn >= nr_pages) {
  			/* Identity map remaining pages */
  			set_phys_range_identity(cur_pfn, cur_pfn + size);
  			break;
  		}
  		if (cur_pfn + size > nr_pages)
  			size = nr_pages - cur_pfn;
  
  		remap_range_size = xen_find_pfn_range(&remap_pfn);
  		if (!remap_range_size) {
  			pr_warn("Unable to find available pfn range, not remapping identity pages\n");
  			xen_set_identity_and_release_chunk(cur_pfn,
  						cur_pfn + left, nr_pages);
  			break;
  		}
  		/* Adjust size to fit in current e820 RAM region */
  		if (size > remap_range_size)
  			size = remap_range_size;
  
  		xen_do_set_identity_and_remap_chunk(cur_pfn, size, remap_pfn);
  
  		/* Update variables to reflect new mappings. */
  		i += size;
  		remap_pfn += size;
  	}
  
  	/*
  	 * If the PFNs are currently mapped, the VA mapping also needs
  	 * to be updated to be 1:1.
  	 */
  	for (pfn = start_pfn; pfn <= max_pfn_mapped && pfn < end_pfn; pfn++)
  		(void)HYPERVISOR_update_va_mapping(
  			(unsigned long)__va(pfn << PAGE_SHIFT),
  			mfn_pte(pfn, PAGE_KERNEL_IO), 0);
  
  	return remap_pfn;
  }
  
  static unsigned long __init xen_count_remap_pages(
  	unsigned long start_pfn, unsigned long end_pfn, unsigned long nr_pages,
  	unsigned long remap_pages)
  {
  	if (start_pfn >= nr_pages)
  		return remap_pages;
  
  	return remap_pages + min(end_pfn, nr_pages) - start_pfn;
  }
  
  static unsigned long __init xen_foreach_remap_area(unsigned long nr_pages,
  	unsigned long (*func)(unsigned long start_pfn, unsigned long end_pfn,
  			      unsigned long nr_pages, unsigned long last_val))
  {
  	phys_addr_t start = 0;
  	unsigned long ret_val = 0;
  	const struct e820_entry *entry = xen_e820_table.entries;
  	int i;
  
  	/*
  	 * Combine non-RAM regions and gaps until a RAM region (or the
  	 * end of the map) is reached, then call the provided function
  	 * to perform its duty on the non-RAM region.
  	 *
  	 * 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; i < xen_e820_table.nr_entries; i++, entry++) {
  		phys_addr_t end = entry->addr + entry->size;
  		if (entry->type == E820_TYPE_RAM || i == xen_e820_table.nr_entries - 1) {
  			unsigned long start_pfn = PFN_DOWN(start);
  			unsigned long end_pfn = PFN_UP(end);
  
  			if (entry->type == E820_TYPE_RAM)
  				end_pfn = PFN_UP(entry->addr);
  
  			if (start_pfn < end_pfn)
  				ret_val = func(start_pfn, end_pfn, nr_pages,
  					       ret_val);
  			start = end;
  		}
  	}
  
  	return ret_val;
  }
  
  /*
   * Remap the memory prepared in xen_do_set_identity_and_remap_chunk().
   * The remap information (which mfn remap to which pfn) is contained in the
   * to be remapped memory itself in a linked list anchored at xen_remap_mfn.
   * This scheme allows to remap the different chunks in arbitrary order while
   * the resulting mapping will be independent from the order.
   */
  void __init xen_remap_memory(void)
  {
  	unsigned long buf = (unsigned long)&xen_remap_buf;
  	unsigned long mfn_save, pfn;
  	unsigned long remapped = 0;
  	unsigned int i;
  	unsigned long pfn_s = ~0UL;
  	unsigned long len = 0;
  
  	mfn_save = virt_to_mfn(buf);
  
  	while (xen_remap_mfn != INVALID_P2M_ENTRY) {
  		/* Map the remap information */
  		set_pte_mfn(buf, xen_remap_mfn, PAGE_KERNEL);
  
  		BUG_ON(xen_remap_mfn != xen_remap_buf.mfns[0]);
  
  		pfn = xen_remap_buf.target_pfn;
  		for (i = 0; i < xen_remap_buf.size; i++) {
  			xen_update_mem_tables(pfn, xen_remap_buf.mfns[i]);
  			remapped++;
  			pfn++;
  		}
  		if (pfn_s == ~0UL || pfn == pfn_s) {
  			pfn_s = xen_remap_buf.target_pfn;
  			len += xen_remap_buf.size;
  		} else if (pfn_s + len == xen_remap_buf.target_pfn) {
  			len += xen_remap_buf.size;
  		} else {
  			xen_del_extra_mem(pfn_s, len);
  			pfn_s = xen_remap_buf.target_pfn;
  			len = xen_remap_buf.size;
  		}
  		xen_remap_mfn = xen_remap_buf.next_area_mfn;
  	}
  
  	if (pfn_s != ~0UL && len)
  		xen_del_extra_mem(pfn_s, len);
  
  	set_pte_mfn(buf, mfn_save, PAGE_KERNEL);
  
  	pr_info("Remapped %ld page(s)\n", remapped);
  }
  
  static unsigned long __init xen_get_pages_limit(void)
  {
  	unsigned long limit;
  
  #ifdef CONFIG_X86_32
  	limit = GB(64) / PAGE_SIZE;
  #else
  	limit = MAXMEM / PAGE_SIZE;
  	if (!xen_initial_domain() && xen_512gb_limit)
  		limit = GB(512) / PAGE_SIZE;
  #endif
  	return limit;
  }
  
  static unsigned long __init xen_get_max_pages(void)
  {
  	unsigned long max_pages, limit;
  	domid_t domid = DOMID_SELF;
  	long ret;
  
  	limit = xen_get_pages_limit();
  	max_pages = limit;
  
  	/*
  	 * For the initial domain we use the maximum reservation as
  	 * the maximum page.
  	 *
  	 * For guest domains the current maximum reservation reflects
  	 * the current maximum rather than the static maximum. In this
  	 * case the e820 map provided to us will cover the static
  	 * maximum region.
  	 */
  	if (xen_initial_domain()) {
  		ret = HYPERVISOR_memory_op(XENMEM_maximum_reservation, &domid);
  		if (ret > 0)
  			max_pages = ret;
  	}
  
  	return min(max_pages, limit);
  }
  
  static void __init xen_align_and_add_e820_region(phys_addr_t start,
  						 phys_addr_t size, int type)
  {
  	phys_addr_t end = start + size;
  
  	/* Align RAM regions to page boundaries. */
  	if (type == E820_TYPE_RAM) {
  		start = PAGE_ALIGN(start);
  		end &= ~((phys_addr_t)PAGE_SIZE - 1);
  #ifdef CONFIG_MEMORY_HOTPLUG
  		/*
  		 * Don't allow adding memory not in E820 map while booting the
  		 * system. Once the balloon driver is up it will remove that
  		 * restriction again.
  		 */
  		max_mem_size = end;
  #endif
  	}
  
  	e820__range_add(start, end - start, type);
  }
  
  static void __init xen_ignore_unusable(void)
  {
  	struct e820_entry *entry = xen_e820_table.entries;
  	unsigned int i;
  
  	for (i = 0; i < xen_e820_table.nr_entries; i++, entry++) {
  		if (entry->type == E820_TYPE_UNUSABLE)
  			entry->type = E820_TYPE_RAM;
  	}
  }
  
  bool __init xen_is_e820_reserved(phys_addr_t start, phys_addr_t size)
  {
  	struct e820_entry *entry;
  	unsigned mapcnt;
  	phys_addr_t end;
  
  	if (!size)
  		return false;
  
  	end = start + size;
  	entry = xen_e820_table.entries;
  
  	for (mapcnt = 0; mapcnt < xen_e820_table.nr_entries; mapcnt++) {
  		if (entry->type == E820_TYPE_RAM && entry->addr <= start &&
  		    (entry->addr + entry->size) >= end)
  			return false;
  
  		entry++;
  	}
  
  	return true;
  }
  
  /*
   * Find a free area in physical memory not yet reserved and compliant with
   * E820 map.
   * Used to relocate pre-allocated areas like initrd or p2m list which are in
   * conflict with the to be used E820 map.
   * In case no area is found, return 0. Otherwise return the physical address
   * of the area which is already reserved for convenience.
   */
  phys_addr_t __init xen_find_free_area(phys_addr_t size)
  {
  	unsigned mapcnt;
  	phys_addr_t addr, start;
  	struct e820_entry *entry = xen_e820_table.entries;
  
  	for (mapcnt = 0; mapcnt < xen_e820_table.nr_entries; mapcnt++, entry++) {
  		if (entry->type != E820_TYPE_RAM || entry->size < size)
  			continue;
  		start = entry->addr;
  		for (addr = start; addr < start + size; addr += PAGE_SIZE) {
  			if (!memblock_is_reserved(addr))
  				continue;
  			start = addr + PAGE_SIZE;
  			if (start + size > entry->addr + entry->size)
  				break;
  		}
  		if (addr >= start + size) {
  			memblock_reserve(start, size);
  			return start;
  		}
  	}
  
  	return 0;
  }
  
  /*
   * Like memcpy, but with physical addresses for dest and src.
   */
  static void __init xen_phys_memcpy(phys_addr_t dest, phys_addr_t src,
  				   phys_addr_t n)
  {
  	phys_addr_t dest_off, src_off, dest_len, src_len, len;
  	void *from, *to;
  
  	while (n) {
  		dest_off = dest & ~PAGE_MASK;
  		src_off = src & ~PAGE_MASK;
  		dest_len = n;
  		if (dest_len > (NR_FIX_BTMAPS << PAGE_SHIFT) - dest_off)
  			dest_len = (NR_FIX_BTMAPS << PAGE_SHIFT) - dest_off;
  		src_len = n;
  		if (src_len > (NR_FIX_BTMAPS << PAGE_SHIFT) - src_off)
  			src_len = (NR_FIX_BTMAPS << PAGE_SHIFT) - src_off;
  		len = min(dest_len, src_len);
  		to = early_memremap(dest - dest_off, dest_len + dest_off);
  		from = early_memremap(src - src_off, src_len + src_off);
  		memcpy(to, from, len);
  		early_memunmap(to, dest_len + dest_off);
  		early_memunmap(from, src_len + src_off);
  		n -= len;
  		dest += len;
  		src += len;
  	}
  }
  
  /*
   * Reserve Xen mfn_list.
   */
  static void __init xen_reserve_xen_mfnlist(void)
  {
  	phys_addr_t start, size;
  
  	if (xen_start_info->mfn_list >= __START_KERNEL_map) {
  		start = __pa(xen_start_info->mfn_list);
  		size = PFN_ALIGN(xen_start_info->nr_pages *
  				 sizeof(unsigned long));
  	} else {
  		start = PFN_PHYS(xen_start_info->first_p2m_pfn);
  		size = PFN_PHYS(xen_start_info->nr_p2m_frames);
  	}
  
  	memblock_reserve(start, size);
  	if (!xen_is_e820_reserved(start, size))
  		return;
  
  #ifdef CONFIG_X86_32
  	/*
  	 * Relocating the p2m on 32 bit system to an arbitrary virtual address
  	 * is not supported, so just give up.
  	 */
  	xen_raw_console_write("Xen hypervisor allocated p2m list conflicts with E820 map\n");
  	BUG();
  #else
  	xen_relocate_p2m();
  	memblock_free(start, size);
  #endif
  }
  
  /**
   * machine_specific_memory_setup - Hook for machine specific memory setup.
   **/
  char * __init xen_memory_setup(void)
  {
  	unsigned long max_pfn, pfn_s, n_pfns;
  	phys_addr_t mem_end, addr, size, chunk_size;
  	u32 type;
  	int rc;
  	struct xen_memory_map memmap;
  	unsigned long max_pages;
  	unsigned long extra_pages = 0;
  	int i;
  	int op;
  
  	xen_parse_512gb();
  	max_pfn = xen_get_pages_limit();
  	max_pfn = min(max_pfn, xen_start_info->nr_pages);
  	mem_end = PFN_PHYS(max_pfn);
  
  	memmap.nr_entries = ARRAY_SIZE(xen_e820_table.entries);
  	set_xen_guest_handle(memmap.buffer, xen_e820_table.entries);
  
  #if defined(CONFIG_MEMORY_HOTPLUG) && defined(CONFIG_XEN_BALLOON)
  	xen_saved_max_mem_size = max_mem_size;
  #endif
  
  	op = xen_initial_domain() ?
  		XENMEM_machine_memory_map :
  		XENMEM_memory_map;
  	rc = HYPERVISOR_memory_op(op, &memmap);
  	if (rc == -ENOSYS) {
  		BUG_ON(xen_initial_domain());
  		memmap.nr_entries = 1;
  		xen_e820_table.entries[0].addr = 0ULL;
  		xen_e820_table.entries[0].size = mem_end;
  		/* 8MB slack (to balance backend allocations). */
  		xen_e820_table.entries[0].size += 8ULL << 20;
  		xen_e820_table.entries[0].type = E820_TYPE_RAM;
  		rc = 0;
  	}
  	BUG_ON(rc);
  	BUG_ON(memmap.nr_entries == 0);
  	xen_e820_table.nr_entries = memmap.nr_entries;
  
  	/*
  	 * Xen won't allow a 1:1 mapping to be created to UNUSABLE
  	 * regions, so if we're using the machine memory map leave the
  	 * region as RAM as it is in the pseudo-physical map.
  	 *
  	 * UNUSABLE regions in domUs are not handled and will need
  	 * a patch in the future.
  	 */
  	if (xen_initial_domain())
  		xen_ignore_unusable();
  
  	/* Make sure the Xen-supplied memory map is well-ordered. */
  	e820__update_table(&xen_e820_table);
  
  	max_pages = xen_get_max_pages();
  
  	/* How many extra pages do we need due to remapping? */
  	max_pages += xen_foreach_remap_area(max_pfn, xen_count_remap_pages);
  
  	if (max_pages > max_pfn)
  		extra_pages += max_pages - max_pfn;
  
  	/*
  	 * Clamp the amount of extra memory to a EXTRA_MEM_RATIO
  	 * factor the base size.  On non-highmem systems, the base
  	 * size is the full initial memory allocation; on highmem it
  	 * is limited to the max size of lowmem, so that it doesn't
  	 * get completely filled.
  	 *
  	 * Make sure we have no memory above max_pages, as this area
  	 * isn't handled by the p2m management.
  	 *
  	 * In principle there could be a problem in lowmem systems if
  	 * the initial memory is also very large with respect to
  	 * lowmem, but we won't try to deal with that here.
  	 */
  	extra_pages = min3(EXTRA_MEM_RATIO * min(max_pfn, PFN_DOWN(MAXMEM)),
  			   extra_pages, max_pages - max_pfn);
  	i = 0;
  	addr = xen_e820_table.entries[0].addr;
  	size = xen_e820_table.entries[0].size;
  	while (i < xen_e820_table.nr_entries) {
  		bool discard = false;
  
  		chunk_size = size;
  		type = xen_e820_table.entries[i].type;
  
  		if (type == E820_TYPE_RAM) {
  			if (addr < mem_end) {
  				chunk_size = min(size, mem_end - addr);
  			} else if (extra_pages) {
  				chunk_size = min(size, PFN_PHYS(extra_pages));
  				pfn_s = PFN_UP(addr);
  				n_pfns = PFN_DOWN(addr + chunk_size) - pfn_s;
  				extra_pages -= n_pfns;
  				xen_add_extra_mem(pfn_s, n_pfns);
  				xen_max_p2m_pfn = pfn_s + n_pfns;
  			} else
  				discard = true;
  		}
  
  		if (!discard)
  			xen_align_and_add_e820_region(addr, chunk_size, type);
  
  		addr += chunk_size;
  		size -= chunk_size;
  		if (size == 0) {
  			i++;
  			if (i < xen_e820_table.nr_entries) {
  				addr = xen_e820_table.entries[i].addr;
  				size = xen_e820_table.entries[i].size;
  			}
  		}
  	}
  
  	/*
  	 * Set the rest as identity mapped, in case PCI BARs are
  	 * located here.
  	 */
  	set_phys_range_identity(addr / PAGE_SIZE, ~0ul);
  
  	/*
  	 * In domU, the ISA region is normal, usable memory, but we
  	 * reserve ISA memory anyway because too many things poke
  	 * about in there.
  	 */
  	e820__range_add(ISA_START_ADDRESS, ISA_END_ADDRESS - ISA_START_ADDRESS, E820_TYPE_RESERVED);
  
  	e820__update_table(e820_table);
  
  	/*
  	 * Check whether the kernel itself conflicts with the target E820 map.
  	 * Failing now is better than running into weird problems later due
  	 * to relocating (and even reusing) pages with kernel text or data.
  	 */
  	if (xen_is_e820_reserved(__pa_symbol(_text),
  			__pa_symbol(__bss_stop) - __pa_symbol(_text))) {
  		xen_raw_console_write("Xen hypervisor allocated kernel memory conflicts with E820 map\n");
  		BUG();
  	}
  
  	/*
  	 * Check for a conflict of the hypervisor supplied page tables with
  	 * the target E820 map.
  	 */
  	xen_pt_check_e820();
  
  	xen_reserve_xen_mfnlist();
  
  	/* Check for a conflict of the initrd with the target E820 map. */
  	if (xen_is_e820_reserved(boot_params.hdr.ramdisk_image,
  				 boot_params.hdr.ramdisk_size)) {
  		phys_addr_t new_area, start, size;
  
  		new_area = xen_find_free_area(boot_params.hdr.ramdisk_size);
  		if (!new_area) {
  			xen_raw_console_write("Can't find new memory area for initrd needed due to E820 map conflict\n");
  			BUG();
  		}
  
  		start = boot_params.hdr.ramdisk_image;
  		size = boot_params.hdr.ramdisk_size;
  		xen_phys_memcpy(new_area, start, size);
  		pr_info("initrd moved from [mem %#010llx-%#010llx] to [mem %#010llx-%#010llx]\n",
  			start, start + size, new_area, new_area + size);
  		memblock_free(start, size);
  		boot_params.hdr.ramdisk_image = new_area;
  		boot_params.ext_ramdisk_image = new_area >> 32;
  	}
  
  	/*
  	 * Set identity map on non-RAM pages and prepare remapping the
  	 * underlying RAM.
  	 */
  	xen_foreach_remap_area(max_pfn, xen_set_identity_and_remap_chunk);
  
  	pr_info("Released %ld page(s)\n", xen_released_pages);
  
  	return "Xen";
  }
  
  /*
   * Set the bit indicating "nosegneg" library variants should be used.
   * We only need to bother in pure 32-bit mode; compat 32-bit processes
   * can have un-truncated segments, so wrapping around is allowed.
   */
  static void __init fiddle_vdso(void)
  {
  #ifdef CONFIG_X86_32
  	u32 *mask = vdso_image_32.data +
  		vdso_image_32.sym_VDSO32_NOTE_MASK;
  	*mask |= 1 << VDSO_NOTE_NONEGSEG_BIT;
  #endif
  }
  
  static int register_callback(unsigned type, const void *func)
  {
  	struct callback_register callback = {
  		.type = type,
  		.address = XEN_CALLBACK(__KERNEL_CS, func),
  		.flags = CALLBACKF_mask_events,
  	};
  
  	return HYPERVISOR_callback_op(CALLBACKOP_register, &callback);
  }
  
  void xen_enable_sysenter(void)
  {
  	int ret;
  	unsigned sysenter_feature;
  
  #ifdef CONFIG_X86_32
  	sysenter_feature = X86_FEATURE_SEP;
  #else
  	sysenter_feature = X86_FEATURE_SYSENTER32;
  #endif
  
  	if (!boot_cpu_has(sysenter_feature))
  		return;
  
  	ret = register_callback(CALLBACKTYPE_sysenter, xen_sysenter_target);
  	if(ret != 0)
  		setup_clear_cpu_cap(sysenter_feature);
  }
  
  void xen_enable_syscall(void)
  {
  #ifdef CONFIG_X86_64
  	int ret;
  
  	ret = register_callback(CALLBACKTYPE_syscall, xen_syscall_target);
  	if (ret != 0) {
  		printk(KERN_ERR "Failed to set syscall callback: %d\n", ret);
  		/* Pretty fatal; 64-bit userspace has no other
  		   mechanism for syscalls. */
  	}
  
  	if (boot_cpu_has(X86_FEATURE_SYSCALL32)) {
  		ret = register_callback(CALLBACKTYPE_syscall32,
  					xen_syscall32_target);
  		if (ret != 0)
  			setup_clear_cpu_cap(X86_FEATURE_SYSCALL32);
  	}
  #endif /* CONFIG_X86_64 */
  }
  
  static void __init xen_pvmmu_arch_setup(void)
  {
  	HYPERVISOR_vm_assist(VMASST_CMD_enable, VMASST_TYPE_4gb_segments);
  	HYPERVISOR_vm_assist(VMASST_CMD_enable, VMASST_TYPE_writable_pagetables);
  
  	HYPERVISOR_vm_assist(VMASST_CMD_enable,
  			     VMASST_TYPE_pae_extended_cr3);
  
  	if (register_callback(CALLBACKTYPE_event,
  			      xen_asm_exc_xen_hypervisor_callback) ||
  	    register_callback(CALLBACKTYPE_failsafe, xen_failsafe_callback))
  		BUG();
  
  	xen_enable_sysenter();
  	xen_enable_syscall();
  }
  
  /* This function is not called for HVM domains */
  void __init xen_arch_setup(void)
  {
  	xen_panic_handler_init();
  	xen_pvmmu_arch_setup();
  
  #ifdef CONFIG_ACPI
  	if (!(xen_start_info->flags & SIF_INITDOMAIN)) {
  		printk(KERN_INFO "ACPI in unprivileged domain disabled\n");
  		disable_acpi();
  	}
  #endif
  
  	memcpy(boot_command_line, xen_start_info->cmd_line,
  	       MAX_GUEST_CMDLINE > COMMAND_LINE_SIZE ?
  	       COMMAND_LINE_SIZE : MAX_GUEST_CMDLINE);
  
  	/* Set up idle, making sure it calls safe_halt() pvop */
  	disable_cpuidle();
  	disable_cpufreq();
  	WARN_ON(xen_set_default_idle());
  	fiddle_vdso();
  #ifdef CONFIG_NUMA
  	numa_off = 1;
  #endif
  }
  