Archipelago » qemu

/*

 * 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.

 *

 */

#include "config.h"

#include <sys/resource.h>

#include "hw/xen_backend.h"

#include "blockdev.h"

#include "bitmap.h"

#include <xen/hvm/params.h>

#include <sys/mman.h>

#include "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 defined(__i386__)

#  define MCACHE_BUCKET_SHIFT 16

#  define MCACHE_MAX_SIZE     (1UL<<31) /* 2GB Cap */

#elif defined(__x86_64__)

#  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 {

    target_phys_addr_t paddr_index;

    uint8_t *vaddr_base;

    unsigned long *valid_mapping;

    uint8_t lock;

    target_phys_addr_t size;

    struct MapCacheEntry *next;

} MapCacheEntry;

typedef struct MapCacheRev {

    uint8_t *vaddr_req;

    target_phys_addr_t paddr_index;

    target_phys_addr_t 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. */

    target_phys_addr_t last_address_index;

    uint8_t *last_address_vaddr;

    unsigned long max_mcache_size;

    unsigned int mcache_bucket_shift;

} 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(void)

{

    unsigned long size;

    struct rlimit rlimit_as;

    mapcache = g_malloc0(sizeof (MapCache));

    QTAILQ_INIT(&mapcache->locked_entries);

    mapcache->last_address_index = -1;

    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,

                             target_phys_addr_t size,

                             target_phys_addr_t address_index)

{

    uint8_t *vaddr_base;

    xen_pfn_t *pfns;

    int *err;

    unsigned int i;

    target_phys_addr_t 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(target_phys_addr_t phys_addr, target_phys_addr_t size,

                       uint8_t lock)

{

    MapCacheEntry *entry, *pentry = NULL;

    target_phys_addr_t address_index  = phys_addr >> MCACHE_BUCKET_SHIFT;

    target_phys_addr_t address_offset = phys_addr & (MCACHE_BUCKET_SIZE - 1);

    target_phys_addr_t __size = size;

    trace_xen_map_cache(phys_addr);

    if (address_index == mapcache->last_address_index && !lock && !__size) {

        trace_xen_map_cache_return(mapcache->last_address_vaddr + address_offset);

        return mapcache->last_address_vaddr + address_offset;

    }

    /* size is always a multiple of MCACHE_BUCKET_SIZE */

    if ((address_offset + (__size % MCACHE_BUCKET_SIZE)) > MCACHE_BUCKET_SIZE)

        __size += MCACHE_BUCKET_SIZE;

    if (__size % MCACHE_BUCKET_SIZE)

        __size += MCACHE_BUCKET_SIZE - (__size % MCACHE_BUCKET_SIZE);

    if (!__size)

        __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, 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, size >> XC_PAGE_SHIFT,

                    entry->valid_mapping)) {

            xen_remap_bucket(entry, __size, address_index);

        }

    }

    if(!test_bits(address_offset >> XC_PAGE_SHIFT, size >> XC_PAGE_SHIFT,

                entry->valid_mapping)) {

        mapcache->last_address_index = -1;

        trace_xen_map_cache_return(NULL);

        return NULL;

    }

    mapcache->last_address_index = address_index;

    mapcache->last_address_vaddr = entry->vaddr_base;

    if (lock) {

        MapCacheRev *reventry = g_malloc0(sizeof(MapCacheRev));

        entry->lock++;

        reventry->vaddr_req = mapcache->last_address_vaddr + address_offset;

        reventry->paddr_index = mapcache->last_address_index;

        reventry->size = entry->size;

        QTAILQ_INSERT_HEAD(&mapcache->locked_entries, reventry, next);

    }

    trace_xen_map_cache_return(mapcache->last_address_vaddr + address_offset);

    return mapcache->last_address_vaddr + address_offset;

}

ram_addr_t xen_ram_addr_from_mapcache(void *ptr)

{

    MapCacheEntry *entry = NULL;

    MapCacheRev *reventry;

    target_phys_addr_t paddr_index;

    target_phys_addr_t 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;

    target_phys_addr_t paddr_index;

    target_phys_addr_t size;

    int found = 0;

    if (mapcache->last_address_vaddr == buffer) {

        mapcache->last_address_index = -1;

    }

    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);

    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 */

    qemu_aio_flush();

    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 (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_address_index = -1;

    mapcache->last_address_vaddr = NULL;

    mapcache_unlock();

}