text: /*
   * Copyright (C) 2011       Citrix Ltd.
   *
   * This work is licensed under the terms of the GNU GPL, version 2.  See
   * the COPYING file in the top-level directory.
   *
   * Contributions after 2012-01-13 are licensed under the terms of the
   * GNU GPL, version 2 or (at your option) any later version.
   */
  
  #include "config.h"
  
  #include <sys/resource.h>
  
  #include "hw/xen/xen_backend.h"
  #include "sysemu/blockdev.h"
  #include "qemu/bitmap.h"
  
  #include <xen/hvm/params.h>
  #include <sys/mman.h>
  
  #include "sysemu/xen-mapcache.h"
  #include "trace.h"
  
  
  //#define MAPCACHE_DEBUG
  
  #ifdef MAPCACHE_DEBUG
  #  define DPRINTF(fmt, ...) do { \
      fprintf(stderr, "xen_mapcache: " fmt, ## __VA_ARGS__); \
  } while (0)
  #else
  #  define DPRINTF(fmt, ...) do { } while (0)
  #endif
  
  #if HOST_LONG_BITS == 32
  #  define MCACHE_BUCKET_SHIFT 16
  #  define MCACHE_MAX_SIZE     (1UL<<31) /* 2GB Cap */
  #else
  #  define MCACHE_BUCKET_SHIFT 20
  #  define MCACHE_MAX_SIZE     (1UL<<35) /* 32GB Cap */
  #endif
  #define MCACHE_BUCKET_SIZE (1UL << MCACHE_BUCKET_SHIFT)
  
  /* This is the size of the virtual address space reserve to QEMU that will not
   * be use by MapCache.
   * From empirical tests I observed that qemu use 75MB more than the
   * max_mcache_size.
   */
  #define NON_MCACHE_MEMORY_SIZE (80 * 1024 * 1024)
  
  #define mapcache_lock()   ((void)0)
  #define mapcache_unlock() ((void)0)
  
  typedef struct MapCacheEntry {
      hwaddr paddr_index;
      uint8_t *vaddr_base;
      unsigned long *valid_mapping;
      uint8_t lock;
      hwaddr size;
      struct MapCacheEntry *next;
  } MapCacheEntry;
  
  typedef struct MapCacheRev {
      uint8_t *vaddr_req;
      hwaddr paddr_index;
      hwaddr size;
      QTAILQ_ENTRY(MapCacheRev) next;
  } MapCacheRev;
  
  typedef struct MapCache {
      MapCacheEntry *entry;
      unsigned long nr_buckets;
      QTAILQ_HEAD(map_cache_head, MapCacheRev) locked_entries;
  
      /* For most cases (>99.9%), the page address is the same. */
      MapCacheEntry *last_entry;
      unsigned long max_mcache_size;
      unsigned int mcache_bucket_shift;
  
      phys_offset_to_gaddr_t phys_offset_to_gaddr;
      void *opaque;
  } MapCache;
  
  static MapCache *mapcache;
  
  static inline int test_bits(int nr, int size, const unsigned long *addr)
  {
      unsigned long res = find_next_zero_bit(addr, size + nr, nr);
      if (res >= nr + size)
          return 1;
      else
          return 0;
  }
  
  void xen_map_cache_init(phys_offset_to_gaddr_t f, void *opaque)
  {
      unsigned long size;
      struct rlimit rlimit_as;
  
      mapcache = g_malloc0(sizeof (MapCache));
  
      mapcache->phys_offset_to_gaddr = f;
      mapcache->opaque = opaque;
  
      QTAILQ_INIT(&mapcache->locked_entries);
  
      if (geteuid() == 0) {
          rlimit_as.rlim_cur = RLIM_INFINITY;
          rlimit_as.rlim_max = RLIM_INFINITY;
          mapcache->max_mcache_size = MCACHE_MAX_SIZE;
      } else {
          getrlimit(RLIMIT_AS, &rlimit_as);
          rlimit_as.rlim_cur = rlimit_as.rlim_max;
  
          if (rlimit_as.rlim_max != RLIM_INFINITY) {
              fprintf(stderr, "Warning: QEMU's maximum size of virtual"
                      " memory is not infinity.\n");
          }
          if (rlimit_as.rlim_max < MCACHE_MAX_SIZE + NON_MCACHE_MEMORY_SIZE) {
              mapcache->max_mcache_size = rlimit_as.rlim_max -
                  NON_MCACHE_MEMORY_SIZE;
          } else {
              mapcache->max_mcache_size = MCACHE_MAX_SIZE;
          }
      }
  
      setrlimit(RLIMIT_AS, &rlimit_as);
  
      mapcache->nr_buckets =
          (((mapcache->max_mcache_size >> XC_PAGE_SHIFT) +
            (1UL << (MCACHE_BUCKET_SHIFT - XC_PAGE_SHIFT)) - 1) >>
           (MCACHE_BUCKET_SHIFT - XC_PAGE_SHIFT));
  
      size = mapcache->nr_buckets * sizeof (MapCacheEntry);
      size = (size + XC_PAGE_SIZE - 1) & ~(XC_PAGE_SIZE - 1);
      DPRINTF("%s, nr_buckets = %lx size %lu\n", __func__,
              mapcache->nr_buckets, size);
      mapcache->entry = g_malloc0(size);
  }
  
  static void xen_remap_bucket(MapCacheEntry *entry,
                               hwaddr size,
                               hwaddr address_index)
  {
      uint8_t *vaddr_base;
      xen_pfn_t *pfns;
      int *err;
      unsigned int i;
      hwaddr nb_pfn = size >> XC_PAGE_SHIFT;
  
      trace_xen_remap_bucket(address_index);
  
      pfns = g_malloc0(nb_pfn * sizeof (xen_pfn_t));
      err = g_malloc0(nb_pfn * sizeof (int));
  
      if (entry->vaddr_base != NULL) {
          if (munmap(entry->vaddr_base, entry->size) != 0) {
              perror("unmap fails");
              exit(-1);
          }
      }
      if (entry->valid_mapping != NULL) {
          g_free(entry->valid_mapping);
          entry->valid_mapping = NULL;
      }
  
      for (i = 0; i < nb_pfn; i++) {
          pfns[i] = (address_index << (MCACHE_BUCKET_SHIFT-XC_PAGE_SHIFT)) + i;
      }
  
      vaddr_base = xc_map_foreign_bulk(xen_xc, xen_domid, PROT_READ|PROT_WRITE,
                                       pfns, err, nb_pfn);
      if (vaddr_base == NULL) {
          perror("xc_map_foreign_bulk");
          exit(-1);
      }
  
      entry->vaddr_base = vaddr_base;
      entry->paddr_index = address_index;
      entry->size = size;
      entry->valid_mapping = (unsigned long *) g_malloc0(sizeof(unsigned long) *
              BITS_TO_LONGS(size >> XC_PAGE_SHIFT));
  
      bitmap_zero(entry->valid_mapping, nb_pfn);
      for (i = 0; i < nb_pfn; i++) {
          if (!err[i]) {
              bitmap_set(entry->valid_mapping, i, 1);
          }
      }
  
      g_free(pfns);
      g_free(err);
  }
  
  uint8_t *xen_map_cache(hwaddr phys_addr, hwaddr size,
                         uint8_t lock)
  {
      MapCacheEntry *entry, *pentry = NULL;
      hwaddr address_index;
      hwaddr address_offset;
      hwaddr __size = size;
      hwaddr __test_bit_size = size;
      bool translated = false;
  
  tryagain:
      address_index  = phys_addr >> MCACHE_BUCKET_SHIFT;
      address_offset = phys_addr & (MCACHE_BUCKET_SIZE - 1);
  
      trace_xen_map_cache(phys_addr);
  
      /* __test_bit_size is always a multiple of XC_PAGE_SIZE */
      if (size) {
          __test_bit_size = size + (phys_addr & (XC_PAGE_SIZE - 1));
  
          if (__test_bit_size % XC_PAGE_SIZE) {
              __test_bit_size += XC_PAGE_SIZE - (__test_bit_size % XC_PAGE_SIZE);
          }
      } else {
          __test_bit_size = XC_PAGE_SIZE;
      }
  
      if (mapcache->last_entry != NULL &&
          mapcache->last_entry->paddr_index == address_index &&
          !lock && !__size &&
          test_bits(address_offset >> XC_PAGE_SHIFT,
                    __test_bit_size >> XC_PAGE_SHIFT,
                    mapcache->last_entry->valid_mapping)) {
          trace_xen_map_cache_return(mapcache->last_entry->vaddr_base + address_offset);
          return mapcache->last_entry->vaddr_base + address_offset;
      }
  
      /* size is always a multiple of MCACHE_BUCKET_SIZE */
      if (size) {
          __size = size + address_offset;
          if (__size % MCACHE_BUCKET_SIZE) {
              __size += MCACHE_BUCKET_SIZE - (__size % MCACHE_BUCKET_SIZE);
          }
      } else {
          __size = MCACHE_BUCKET_SIZE;
      }
  
      entry = &mapcache->entry[address_index % mapcache->nr_buckets];
  
      while (entry && entry->lock && entry->vaddr_base &&
              (entry->paddr_index != address_index || entry->size != __size ||
               !test_bits(address_offset >> XC_PAGE_SHIFT,
                   __test_bit_size >> XC_PAGE_SHIFT,
                   entry->valid_mapping))) {
          pentry = entry;
          entry = entry->next;
      }
      if (!entry) {
          entry = g_malloc0(sizeof (MapCacheEntry));
          pentry->next = entry;
          xen_remap_bucket(entry, __size, address_index);
      } else if (!entry->lock) {
          if (!entry->vaddr_base || entry->paddr_index != address_index ||
                  entry->size != __size ||
                  !test_bits(address_offset >> XC_PAGE_SHIFT,
                      __test_bit_size >> XC_PAGE_SHIFT,
                      entry->valid_mapping)) {
              xen_remap_bucket(entry, __size, address_index);
          }
      }
  
      if(!test_bits(address_offset >> XC_PAGE_SHIFT,
                  __test_bit_size >> XC_PAGE_SHIFT,
                  entry->valid_mapping)) {
          mapcache->last_entry = NULL;
          if (!translated && mapcache->phys_offset_to_gaddr) {
              phys_addr = mapcache->phys_offset_to_gaddr(phys_addr, size, mapcache->opaque);
              translated = true;
              goto tryagain;
          }
          trace_xen_map_cache_return(NULL);
          return NULL;
      }
  
      mapcache->last_entry = entry;
      if (lock) {
          MapCacheRev *reventry = g_malloc0(sizeof(MapCacheRev));
          entry->lock++;
          reventry->vaddr_req = mapcache->last_entry->vaddr_base + address_offset;
          reventry->paddr_index = mapcache->last_entry->paddr_index;
          reventry->size = entry->size;
          QTAILQ_INSERT_HEAD(&mapcache->locked_entries, reventry, next);
      }
  
      trace_xen_map_cache_return(mapcache->last_entry->vaddr_base + address_offset);
      return mapcache->last_entry->vaddr_base + address_offset;
  }
  
  ram_addr_t xen_ram_addr_from_mapcache(void *ptr)
  {
      MapCacheEntry *entry = NULL;
      MapCacheRev *reventry;
      hwaddr paddr_index;
      hwaddr size;
      int found = 0;
  
      QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
          if (reventry->vaddr_req == ptr) {
              paddr_index = reventry->paddr_index;
              size = reventry->size;
              found = 1;
              break;
          }
      }
      if (!found) {
          fprintf(stderr, "%s, could not find %p\n", __func__, ptr);
          QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
              DPRINTF("   "TARGET_FMT_plx" -> %p is present\n", reventry->paddr_index,
                      reventry->vaddr_req);
          }
          abort();
          return 0;
      }
  
      entry = &mapcache->entry[paddr_index % mapcache->nr_buckets];
      while (entry && (entry->paddr_index != paddr_index || entry->size != size)) {
          entry = entry->next;
      }
      if (!entry) {
          DPRINTF("Trying to find address %p that is not in the mapcache!\n", ptr);
          return 0;
      }
      return (reventry->paddr_index << MCACHE_BUCKET_SHIFT) +
          ((unsigned long) ptr - (unsigned long) entry->vaddr_base);
  }
  
  void xen_invalidate_map_cache_entry(uint8_t *buffer)
  {
      MapCacheEntry *entry = NULL, *pentry = NULL;
      MapCacheRev *reventry;
      hwaddr paddr_index;
      hwaddr size;
      int found = 0;
  
      QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
          if (reventry->vaddr_req == buffer) {
              paddr_index = reventry->paddr_index;
              size = reventry->size;
              found = 1;
              break;
          }
      }
      if (!found) {
          DPRINTF("%s, could not find %p\n", __func__, buffer);
          QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
              DPRINTF("   "TARGET_FMT_plx" -> %p is present\n", reventry->paddr_index, reventry->vaddr_req);
          }
          return;
      }
      QTAILQ_REMOVE(&mapcache->locked_entries, reventry, next);
      g_free(reventry);
  
      if (mapcache->last_entry != NULL &&
          mapcache->last_entry->paddr_index == paddr_index) {
          mapcache->last_entry = NULL;
      }
  
      entry = &mapcache->entry[paddr_index % mapcache->nr_buckets];
      while (entry && (entry->paddr_index != paddr_index || entry->size != size)) {
          pentry = entry;
          entry = entry->next;
      }
      if (!entry) {
          DPRINTF("Trying to unmap address %p that is not in the mapcache!\n", buffer);
          return;
      }
      entry->lock--;
      if (entry->lock > 0 || pentry == NULL) {
          return;
      }
  
      pentry->next = entry->next;
      if (munmap(entry->vaddr_base, entry->size) != 0) {
          perror("unmap fails");
          exit(-1);
      }
      g_free(entry->valid_mapping);
      g_free(entry);
  }
  
  void xen_invalidate_map_cache(void)
  {
      unsigned long i;
      MapCacheRev *reventry;
  
      /* Flush pending AIO before destroying the mapcache */
      bdrv_drain_all();
  
      QTAILQ_FOREACH(reventry, &mapcache->locked_entries, next) {
          DPRINTF("There should be no locked mappings at this time, "
                  "but "TARGET_FMT_plx" -> %p is present\n",
                  reventry->paddr_index, reventry->vaddr_req);
      }
  
      mapcache_lock();
  
      for (i = 0; i < mapcache->nr_buckets; i++) {
          MapCacheEntry *entry = &mapcache->entry[i];
  
          if (entry->vaddr_base == NULL) {
              continue;
          }
          if (entry->lock > 0) {
              continue;
          }
  
          if (munmap(entry->vaddr_base, entry->size) != 0) {
              perror("unmap fails");
              exit(-1);
          }
  
          entry->paddr_index = 0;
          entry->vaddr_base = NULL;
          entry->size = 0;
          g_free(entry->valid_mapping);
          entry->valid_mapping = NULL;
      }
  
      mapcache->last_entry = NULL;
  
      mapcache_unlock();
  }
  