/*
   * Machine specific setup for xen
   *
   * Jeremy Fitzhardinge <jeremy@xensource.com>, XenSource Inc, 2007
   */
  
  #include <linux/module.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 <asm/elf.h>
  #include <asm/vdso.h>
  #include <asm/e820.h>
  #include <asm/setup.h>
  #include <asm/acpi.h>
  #include <asm/numa.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 "mmu.h"
  #include "xen-ops.h"
  #include "vdso.h"
  
  /* These are code, but not functions.  Defined in entry.S */
  extern const char xen_hypervisor_callback[];
  extern const char xen_failsafe_callback[];
  #ifdef CONFIG_X86_64
  extern asmlinkage void nmi(void);
  #endif
  extern void xen_sysenter_target(void);
  extern void xen_syscall_target(void);
  extern void xen_syscall32_target(void);
  
  /* 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;
  
  /* 
   * 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 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
  ");
  
  	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)
  ", pfn))
  			continue;
  		WARN(mfn != INVALID_P2M_ENTRY, "Trying to remove %lx which has %lx mfn!
  ",
  			pfn, mfn);
  
  		__set_phys_to_machine(pfn, INVALID_P2M_ENTRY);
  	}
  }
  
  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
  ",
  		     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
  ",
  		       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);
  		/* If the E820 falls within the nr_pages, we want to start
  		 * at the nr_pages PFN.
  		 * If that would mean going past the E820 entry, skip it
  		 */
  		if (s_pfn <= max_pfn) {
  			capacity = e_pfn - max_pfn;
  			dest_pfn = max_pfn;
  		} else {
  			capacity = e_pfn - s_pfn;
  			dest_pfn = s_pfn;
  		}
  
  		if (credits_left < capacity)
  			capacity = credits_left;
  
  		pfns = xen_do_chunk(dest_pfn, dest_pfn + capacity, false);
  		done += pfns;
  		*last_pfn = (dest_pfn + pfns);
  		if (pfns < capacity)
  			break;
  		credits_left -= pfns;
  	}
  	return done;
  }
  
  static void __init xen_set_identity_and_release_chunk(
  	unsigned long start_pfn, unsigned long end_pfn, unsigned long nr_pages,
  	unsigned long *released, unsigned long *identity)
  {
  	unsigned long pfn;
  
  	/*
  	 * If the PFNs are currently mapped, clear the mappings
  	 * (except for the ISA region which must be 1:1 mapped) to
  	 * release the refcounts (in Xen) on the original frames.
  	 */
  
  	/*
  	 * PVH E820 matches the hypervisor's P2M which means we need to
  	 * account for the proper values of *release and *identity.
  	 */
  	for (pfn = start_pfn; !xen_feature(XENFEAT_auto_translated_physmap) &&
  	     pfn <= max_pfn_mapped && pfn < end_pfn; pfn++) {
  		pte_t pte = __pte_ma(0);
  
  		if (pfn < PFN_UP(ISA_END_ADDRESS))
  			pte = mfn_pte(pfn, PAGE_KERNEL_IO);
  
  		(void)HYPERVISOR_update_va_mapping(
  			(unsigned long)__va(pfn << PAGE_SHIFT), pte, 0);
  	}
  
  	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);
  }
  
  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)
  				xen_set_identity_and_release_chunk(
  					start_pfn, end_pfn, nr_pages,
  					&released, &identity);
  
  			start = end;
  		}
  	}
  
  	if (released)
  		printk(KERN_INFO "Released %lu pages of unused memory
  ", released);
  	if (identity)
  		printk(KERN_INFO "Set %ld page(s) to 1-1 mapping
  ", identity);
  
  	return released;
  }
  
  static unsigned long __init xen_get_max_pages(void)
  {
  	unsigned long max_pages = MAX_DOMAIN_PAGES;
  	domid_t domid = DOMID_SELF;
  	int ret;
  
  	/*
  	 * 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, MAX_DOMAIN_PAGES);
  }
  
  static void xen_align_and_add_e820_region(u64 start, u64 size, int type)
  {
  	u64 end = start + size;
  
  	/* Align RAM regions to page boundaries. */
  	if (type == E820_RAM) {
  		start = PAGE_ALIGN(start);
  		end &= ~((u64)PAGE_SIZE - 1);
  	}
  
  	e820_add_region(start, end - start, type);
  }
  
  void xen_ignore_unusable(struct e820entry *list, size_t map_size)
  {
  	struct e820entry *entry;
  	unsigned int i;
  
  	for (i = 0, entry = list; i < map_size; i++, entry++) {
  		if (entry->type == E820_UNUSABLE)
  			entry->type = E820_RAM;
  	}
  }
  
  /**
   * machine_specific_memory_setup - Hook for machine specific memory setup.
   **/
  char * __init xen_memory_setup(void)
  {
  	static struct e820entry map[E820MAX] __initdata;
  
  	unsigned long max_pfn = xen_start_info->nr_pages;
  	unsigned long long mem_end;
  	int rc;
  	struct xen_memory_map memmap;
  	unsigned long max_pages;
  	unsigned long last_pfn = 0;
  	unsigned long extra_pages = 0;
  	unsigned long populated;
  	int i;
  	int op;
  
  	max_pfn = min(MAX_DOMAIN_PAGES, max_pfn);
  	mem_end = PFN_PHYS(max_pfn);
  
  	memmap.nr_entries = E820MAX;
  	set_xen_guest_handle(memmap.buffer, map);
  
  	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;
  		map[0].addr = 0ULL;
  		map[0].size = mem_end;
  		/* 8MB slack (to balance backend allocations). */
  		map[0].size += 8ULL << 20;
  		map[0].type = E820_RAM;
  		rc = 0;
  	}
  	BUG_ON(rc);
  
  	/*
  	 * 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(map, memmap.nr_entries);
  
  	/* Make sure the Xen-supplied memory map is well-ordered. */
  	sanitize_e820_map(map, memmap.nr_entries, &memmap.nr_entries);
  
  	max_pages = xen_get_max_pages();
  	if (max_pages > max_pfn)
  		extra_pages += max_pages - max_pfn;
  
  	/*
  	 * Set P2M for all non-RAM pages and E820 gaps to be identity
  	 * type PFNs.  Any RAM pages that would be made inaccesible by
  	 * this are first released.
  	 */
  	xen_released_pages = xen_set_identity_and_release(
  		map, memmap.nr_entries, max_pfn);
  
  	/*
  	 * Populate back the non-RAM pages and E820 gaps that had been
  	 * released. */
  	populated = xen_populate_chunk(map, memmap.nr_entries,
  			max_pfn, &last_pfn, xen_released_pages);
  
  	xen_released_pages -= populated;
  	extra_pages += xen_released_pages;
  
  	if (last_pfn > max_pfn) {
  		max_pfn = min(MAX_DOMAIN_PAGES, last_pfn);
  		mem_end = PFN_PHYS(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.
  	 *
  	 * 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 = min(EXTRA_MEM_RATIO * min(max_pfn, PFN_DOWN(MAXMEM)),
  			  extra_pages);
  	i = 0;
  	while (i < memmap.nr_entries) {
  		u64 addr = map[i].addr;
  		u64 size = map[i].size;
  		u32 type = map[i].type;
  
  		if (type == E820_RAM) {
  			if (addr < mem_end) {
  				size = min(size, mem_end - addr);
  			} else if (extra_pages) {
  				size = min(size, (u64)extra_pages * PAGE_SIZE);
  				extra_pages -= size / PAGE_SIZE;
  				xen_add_extra_mem(addr, size);
  			} else
  				type = E820_UNUSABLE;
  		}
  
  		xen_align_and_add_e820_region(addr, size, type);
  
  		map[i].addr += size;
  		map[i].size -= size;
  		if (map[i].size == 0)
  			i++;
  	}
  
  	/*
  	 * In domU, the ISA region is normal, usable memory, but we
  	 * reserve ISA memory anyway because too many things poke
  	 * about in there.
  	 */
  	e820_add_region(ISA_START_ADDRESS, ISA_END_ADDRESS - ISA_START_ADDRESS,
  			E820_RESERVED);
  
  	/*
  	 * Reserve Xen bits:
  	 *  - mfn_list
  	 *  - xen_start_info
  	 * See comment above "struct start_info" in <xen/interface/xen.h>
  	 * We tried to make the the memblock_reserve more selective so
  	 * that it would be clear what region is reserved. Sadly we ran
  	 * in the problem wherein on a 64-bit hypervisor with a 32-bit
  	 * initial domain, the pt_base has the cr3 value which is not
  	 * neccessarily where the pagetable starts! As Jan put it: "
  	 * Actually, the adjustment turns out to be correct: The page
  	 * tables for a 32-on-64 dom0 get allocated in the order "first L1",
  	 * "first L2", "first L3", so the offset to the page table base is
  	 * indeed 2. When reading xen/include/public/xen.h's comment
  	 * very strictly, this is not a violation (since there nothing is said
  	 * that the first thing in the page table space is pointed to by
  	 * pt_base; I admit that this seems to be implied though, namely
  	 * do I think that it is implied that the page table space is the
  	 * range [pt_base, pt_base + nt_pt_frames), whereas that
  	 * range here indeed is [pt_base - 2, pt_base - 2 + nt_pt_frames),
  	 * which - without a priori knowledge - the kernel would have
  	 * difficulty to figure out)." - so lets just fall back to the
  	 * easy way and reserve the whole region.
  	 */
  	memblock_reserve(__pa(xen_start_info->mfn_list),
  			 xen_start_info->pt_base - xen_start_info->mfn_list);
  
  	sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map);
  
  	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;
  	mask = VDSO32_SYMBOL(&vdso32_int80_start, NOTE_MASK);
  	*mask |= 1 << VDSO_NOTE_NONEGSEG_BIT;
  	mask = VDSO32_SYMBOL(&vdso32_sysenter_start, 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
  ", 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 */
  }
  
  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_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();
  	if (!xen_feature(XENFEAT_auto_translated_physmap))
  		xen_pvmmu_arch_setup();
  
  #ifdef CONFIG_ACPI
  	if (!(xen_start_info->flags & SIF_INITDOMAIN)) {
  		printk(KERN_INFO "ACPI in unprivileged domain disabled
  ");
  		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
  }