Archipelago » qemu

/*

 * QEMU KVM support

 *

 * Copyright IBM, Corp. 2008

 *           Red Hat, Inc. 2008

 *

 * Authors:

 *  Anthony Liguori   <aliguori@us.ibm.com>

 *  Glauber Costa     <gcosta@redhat.com>

 *

 * This work is licensed under the terms of the GNU GPL, version 2 or later.

 * See the COPYING file in the top-level directory.

 *

 */

#include <sys/types.h>

#include <sys/ioctl.h>

#include <sys/mman.h>

#include <stdarg.h>

#include <linux/kvm.h>

#include "qemu-common.h"

#include "sysemu.h"

#include "gdbstub.h"

#include "kvm.h"

/* KVM uses PAGE_SIZE in it's definition of COALESCED_MMIO_MAX */

#define PAGE_SIZE TARGET_PAGE_SIZE

//#define DEBUG_KVM

#ifdef DEBUG_KVM

#define dprintf(fmt, ...) \

    do { fprintf(stderr, fmt, ## __VA_ARGS__); } while (0)

#else

#define dprintf(fmt, ...) \

    do { } while (0)

#endif

typedef struct KVMSlot

{

    target_phys_addr_t start_addr;

    ram_addr_t memory_size;

    ram_addr_t phys_offset;

    int slot;

    int flags;

} KVMSlot;

typedef struct kvm_dirty_log KVMDirtyLog;

int kvm_allowed = 0;

struct KVMState

{

    KVMSlot slots[32];

    int fd;

    int vmfd;

    int coalesced_mmio;

#ifdef KVM_CAP_SET_GUEST_DEBUG

    struct kvm_sw_breakpoint_head kvm_sw_breakpoints;

#endif

};

static KVMState *kvm_state;

static KVMSlot *kvm_alloc_slot(KVMState *s)

{

    int i;

    for (i = 0; i < ARRAY_SIZE(s->slots); i++) {

        /* KVM private memory slots */

        if (i >= 8 && i < 12)

            continue;

        if (s->slots[i].memory_size == 0)

            return &s->slots[i];

    }

    fprintf(stderr, "%s: no free slot available\n", __func__);

    abort();

}

static KVMSlot *kvm_lookup_matching_slot(KVMState *s,

                                         target_phys_addr_t start_addr,

                                         target_phys_addr_t end_addr)

{

    int i;

    for (i = 0; i < ARRAY_SIZE(s->slots); i++) {

        KVMSlot *mem = &s->slots[i];

        if (start_addr == mem->start_addr &&

            end_addr == mem->start_addr + mem->memory_size) {

            return mem;

        }

    }

    return NULL;

}

/*

 * Find overlapping slot with lowest start address

 */

static KVMSlot *kvm_lookup_overlapping_slot(KVMState *s,

                                            target_phys_addr_t start_addr,

                                            target_phys_addr_t end_addr)

{

    KVMSlot *found = NULL;

    int i;

    for (i = 0; i < ARRAY_SIZE(s->slots); i++) {

        KVMSlot *mem = &s->slots[i];

        if (mem->memory_size == 0 ||

            (found && found->start_addr < mem->start_addr)) {

            continue;

        }

        if (end_addr > mem->start_addr &&

            start_addr < mem->start_addr + mem->memory_size) {

            found = mem;

        }

    }

    return found;

}

static int kvm_set_user_memory_region(KVMState *s, KVMSlot *slot)

{

    struct kvm_userspace_memory_region mem;

    mem.slot = slot->slot;

    mem.guest_phys_addr = slot->start_addr;

    mem.memory_size = slot->memory_size;

    mem.userspace_addr = (unsigned long)qemu_get_ram_ptr(slot->phys_offset);

    mem.flags = slot->flags;

    return kvm_vm_ioctl(s, KVM_SET_USER_MEMORY_REGION, &mem);

}

int kvm_init_vcpu(CPUState *env)

{

    KVMState *s = kvm_state;

    long mmap_size;

    int ret;

    dprintf("kvm_init_vcpu\n");

    ret = kvm_vm_ioctl(s, KVM_CREATE_VCPU, env->cpu_index);

    if (ret < 0) {

        dprintf("kvm_create_vcpu failed\n");

        goto err;

    }

    env->kvm_fd = ret;

    env->kvm_state = s;

    mmap_size = kvm_ioctl(s, KVM_GET_VCPU_MMAP_SIZE, 0);

    if (mmap_size < 0) {

        dprintf("KVM_GET_VCPU_MMAP_SIZE failed\n");

        goto err;

    }

    env->kvm_run = mmap(NULL, mmap_size, PROT_READ | PROT_WRITE, MAP_SHARED,

                        env->kvm_fd, 0);

    if (env->kvm_run == MAP_FAILED) {

        ret = -errno;

        dprintf("mmap'ing vcpu state failed\n");

        goto err;

    }

    ret = kvm_arch_init_vcpu(env);

err:

    return ret;

}

int kvm_sync_vcpus(void)

{

    CPUState *env;

    for (env = first_cpu; env != NULL; env = env->next_cpu) {

        int ret;

        ret = kvm_arch_put_registers(env);

        if (ret)

            return ret;

    }

    return 0;

}

/*

 * dirty pages logging control

 */

static int kvm_dirty_pages_log_change(target_phys_addr_t phys_addr,

                                      ram_addr_t size, unsigned flags,

                                      unsigned mask)

{

    KVMState *s = kvm_state;

    KVMSlot *mem = kvm_lookup_matching_slot(s, phys_addr, phys_addr + size);

    if (mem == NULL)  {

            fprintf(stderr, "BUG: %s: invalid parameters " TARGET_FMT_plx "-"

                    TARGET_FMT_plx "\n", __func__, phys_addr,

                    phys_addr + size - 1);

            return -EINVAL;

    }

    flags = (mem->flags & ~mask) | flags;

    /* Nothing changed, no need to issue ioctl */

    if (flags == mem->flags)

            return 0;

    mem->flags = flags;

    return kvm_set_user_memory_region(s, mem);

}

int kvm_log_start(target_phys_addr_t phys_addr, ram_addr_t size)

{

        return kvm_dirty_pages_log_change(phys_addr, size,

                                          KVM_MEM_LOG_DIRTY_PAGES,

                                          KVM_MEM_LOG_DIRTY_PAGES);

}

int kvm_log_stop(target_phys_addr_t phys_addr, ram_addr_t size)

{

        return kvm_dirty_pages_log_change(phys_addr, size,

                                          0,

                                          KVM_MEM_LOG_DIRTY_PAGES);

}

/**

 * kvm_physical_sync_dirty_bitmap - Grab dirty bitmap from kernel space

 * This function updates qemu's dirty bitmap using cpu_physical_memory_set_dirty().

 * This means all bits are set to dirty.

 *

 * @start_add: start of logged region.

 * @end_addr: end of logged region.

 */

void kvm_physical_sync_dirty_bitmap(target_phys_addr_t start_addr,

                                    target_phys_addr_t end_addr)

{

    KVMState *s = kvm_state;

    KVMDirtyLog d;

    KVMSlot *mem = kvm_lookup_matching_slot(s, start_addr, end_addr);

    unsigned long alloc_size;

    ram_addr_t addr;

    target_phys_addr_t phys_addr = start_addr;

    dprintf("sync addr: " TARGET_FMT_lx " into %lx\n", start_addr,

            mem->phys_offset);

    if (mem == NULL) {

            fprintf(stderr, "BUG: %s: invalid parameters " TARGET_FMT_plx "-"

                    TARGET_FMT_plx "\n", __func__, phys_addr, end_addr - 1);

            return;

    }

    alloc_size = mem->memory_size >> TARGET_PAGE_BITS / sizeof(d.dirty_bitmap);

    d.dirty_bitmap = qemu_mallocz(alloc_size);

    d.slot = mem->slot;

    dprintf("slot %d, phys_addr %llx, uaddr: %llx\n",

            d.slot, mem->start_addr, mem->phys_offset);

    if (kvm_vm_ioctl(s, KVM_GET_DIRTY_LOG, &d) == -1) {

        dprintf("ioctl failed %d\n", errno);

        goto out;

    }

    phys_addr = start_addr;

    for (addr = mem->phys_offset; phys_addr < end_addr; phys_addr+= TARGET_PAGE_SIZE, addr += TARGET_PAGE_SIZE) {

        unsigned long *bitmap = (unsigned long *)d.dirty_bitmap;

        unsigned nr = (phys_addr - start_addr) >> TARGET_PAGE_BITS;

        unsigned word = nr / (sizeof(*bitmap) * 8);

        unsigned bit = nr % (sizeof(*bitmap) * 8);

        if ((bitmap[word] >> bit) & 1)

            cpu_physical_memory_set_dirty(addr);

    }

out:

    qemu_free(d.dirty_bitmap);

}

int kvm_coalesce_mmio_region(target_phys_addr_t start, ram_addr_t size)

{

    int ret = -ENOSYS;

#ifdef KVM_CAP_COALESCED_MMIO

    KVMState *s = kvm_state;

    if (s->coalesced_mmio) {

        struct kvm_coalesced_mmio_zone zone;

        zone.addr = start;

        zone.size = size;

        ret = kvm_vm_ioctl(s, KVM_REGISTER_COALESCED_MMIO, &zone);

    }

#endif

    return ret;

}

int kvm_uncoalesce_mmio_region(target_phys_addr_t start, ram_addr_t size)

{

    int ret = -ENOSYS;

#ifdef KVM_CAP_COALESCED_MMIO

    KVMState *s = kvm_state;

    if (s->coalesced_mmio) {

        struct kvm_coalesced_mmio_zone zone;

        zone.addr = start;

        zone.size = size;

        ret = kvm_vm_ioctl(s, KVM_UNREGISTER_COALESCED_MMIO, &zone);

    }

#endif

    return ret;

}

int kvm_init(int smp_cpus)

{

    KVMState *s;

    int ret;

    int i;

    if (smp_cpus > 1)

        return -EINVAL;

    s = qemu_mallocz(sizeof(KVMState));

#ifdef KVM_CAP_SET_GUEST_DEBUG

    TAILQ_INIT(&s->kvm_sw_breakpoints);

#endif

    for (i = 0; i < ARRAY_SIZE(s->slots); i++)

        s->slots[i].slot = i;

    s->vmfd = -1;

    s->fd = open("/dev/kvm", O_RDWR);

    if (s->fd == -1) {

        fprintf(stderr, "Could not access KVM kernel module: %m\n");

        ret = -errno;

        goto err;

    }

    ret = kvm_ioctl(s, KVM_GET_API_VERSION, 0);

    if (ret < KVM_API_VERSION) {

        if (ret > 0)

            ret = -EINVAL;

        fprintf(stderr, "kvm version too old\n");

        goto err;

    }

    if (ret > KVM_API_VERSION) {

        ret = -EINVAL;

        fprintf(stderr, "kvm version not supported\n");

        goto err;

    }

    s->vmfd = kvm_ioctl(s, KVM_CREATE_VM, 0);

    if (s->vmfd < 0)

        goto err;

    /* initially, KVM allocated its own memory and we had to jump through

     * hooks to make phys_ram_base point to this.  Modern versions of KVM

     * just use a user allocated buffer so we can use regular pages

     * unmodified.  Make sure we have a sufficiently modern version of KVM.

     */

    ret = kvm_ioctl(s, KVM_CHECK_EXTENSION, KVM_CAP_USER_MEMORY);

    if (ret <= 0) {

        if (ret == 0)

            ret = -EINVAL;

        fprintf(stderr, "kvm does not support KVM_CAP_USER_MEMORY\n");

        goto err;

    }

    /* There was a nasty bug in < kvm-80 that prevents memory slots from being

     * destroyed properly.  Since we rely on this capability, refuse to work

     * with any kernel without this capability. */

    ret = kvm_ioctl(s, KVM_CHECK_EXTENSION,

                    KVM_CAP_DESTROY_MEMORY_REGION_WORKS);

    if (ret <= 0) {

        if (ret == 0)

            ret = -EINVAL;

        fprintf(stderr,

                "KVM kernel module broken (DESTROY_MEMORY_REGION)\n"

                "Please upgrade to at least kvm-81.\n");

        goto err;

    }

    s->coalesced_mmio = 0;

#ifdef KVM_CAP_COALESCED_MMIO

    ret = kvm_ioctl(s, KVM_CHECK_EXTENSION, KVM_CAP_COALESCED_MMIO);

    if (ret > 0)

        s->coalesced_mmio = ret;

#endif

    ret = kvm_arch_init(s, smp_cpus);

    if (ret < 0)

        goto err;

    kvm_state = s;

    return 0;

err:

    if (s) {

        if (s->vmfd != -1)

            close(s->vmfd);

        if (s->fd != -1)

            close(s->fd);

    }

    qemu_free(s);

    return ret;

}

static int kvm_handle_io(CPUState *env, uint16_t port, void *data,

                         int direction, int size, uint32_t count)

{

    int i;

    uint8_t *ptr = data;

    for (i = 0; i < count; i++) {

        if (direction == KVM_EXIT_IO_IN) {

            switch (size) {

            case 1:

                stb_p(ptr, cpu_inb(env, port));

                break;

            case 2:

                stw_p(ptr, cpu_inw(env, port));

                break;

            case 4:

                stl_p(ptr, cpu_inl(env, port));

                break;

            }

        } else {

            switch (size) {

            case 1:

                cpu_outb(env, port, ldub_p(ptr));

                break;

            case 2:

                cpu_outw(env, port, lduw_p(ptr));

                break;

            case 4:

                cpu_outl(env, port, ldl_p(ptr));

                break;

            }

        }

        ptr += size;

    }

    return 1;

}

static void kvm_run_coalesced_mmio(CPUState *env, struct kvm_run *run)

{

#ifdef KVM_CAP_COALESCED_MMIO

    KVMState *s = kvm_state;

    if (s->coalesced_mmio) {

        struct kvm_coalesced_mmio_ring *ring;

        ring = (void *)run + (s->coalesced_mmio * TARGET_PAGE_SIZE);

        while (ring->first != ring->last) {

            struct kvm_coalesced_mmio *ent;

            ent = &ring->coalesced_mmio[ring->first];

            cpu_physical_memory_write(ent->phys_addr, ent->data, ent->len);

            /* FIXME smp_wmb() */

            ring->first = (ring->first + 1) % KVM_COALESCED_MMIO_MAX;

        }

    }

#endif

}

int kvm_cpu_exec(CPUState *env)

{

    struct kvm_run *run = env->kvm_run;

    int ret;

    dprintf("kvm_cpu_exec()\n");

    do {

        kvm_arch_pre_run(env, run);

        if (env->exit_request) {

            dprintf("interrupt exit requested\n");

            ret = 0;

            break;

        }

        ret = kvm_vcpu_ioctl(env, KVM_RUN, 0);

        kvm_arch_post_run(env, run);

        if (ret == -EINTR || ret == -EAGAIN) {

            dprintf("io window exit\n");

            ret = 0;

            break;

        }

        if (ret < 0) {

            dprintf("kvm run failed %s\n", strerror(-ret));

            abort();

        }

        kvm_run_coalesced_mmio(env, run);

        ret = 0; /* exit loop */

        switch (run->exit_reason) {

        case KVM_EXIT_IO:

            dprintf("handle_io\n");

            ret = kvm_handle_io(env, run->io.port,

                                (uint8_t *)run + run->io.data_offset,

                                run->io.direction,

                                run->io.size,

                                run->io.count);

            break;

        case KVM_EXIT_MMIO:

            dprintf("handle_mmio\n");

            cpu_physical_memory_rw(run->mmio.phys_addr,

                                   run->mmio.data,

                                   run->mmio.len,

                                   run->mmio.is_write);

            ret = 1;

            break;

        case KVM_EXIT_IRQ_WINDOW_OPEN:

            dprintf("irq_window_open\n");

            break;

        case KVM_EXIT_SHUTDOWN:

            dprintf("shutdown\n");

            qemu_system_reset_request();

            ret = 1;

            break;

        case KVM_EXIT_UNKNOWN:

            dprintf("kvm_exit_unknown\n");

            break;

        case KVM_EXIT_FAIL_ENTRY:

            dprintf("kvm_exit_fail_entry\n");

            break;

        case KVM_EXIT_EXCEPTION:

            dprintf("kvm_exit_exception\n");

            break;

        case KVM_EXIT_DEBUG:

            dprintf("kvm_exit_debug\n");

#ifdef KVM_CAP_SET_GUEST_DEBUG

            if (kvm_arch_debug(&run->debug.arch)) {

                gdb_set_stop_cpu(env);

                vm_stop(EXCP_DEBUG);

                env->exception_index = EXCP_DEBUG;

                return 0;

            }

            /* re-enter, this exception was guest-internal */

            ret = 1;

#endif /* KVM_CAP_SET_GUEST_DEBUG */

            break;

        default:

            dprintf("kvm_arch_handle_exit\n");

            ret = kvm_arch_handle_exit(env, run);

            break;

        }

    } while (ret > 0);

    if (env->exit_request) {

        env->exit_request = 0;

        env->exception_index = EXCP_INTERRUPT;

    }

    return ret;

}

void kvm_set_phys_mem(target_phys_addr_t start_addr,

                      ram_addr_t size,

                      ram_addr_t phys_offset)

{

    KVMState *s = kvm_state;

    ram_addr_t flags = phys_offset & ~TARGET_PAGE_MASK;

    KVMSlot *mem, old;

    int err;

    if (start_addr & ~TARGET_PAGE_MASK) {

        fprintf(stderr, "Only page-aligned memory slots supported\n");

        abort();

    }

    /* KVM does not support read-only slots */

    phys_offset &= ~IO_MEM_ROM;

    while (1) {

        mem = kvm_lookup_overlapping_slot(s, start_addr, start_addr + size);

        if (!mem) {

            break;

        }

        if (flags < IO_MEM_UNASSIGNED && start_addr >= mem->start_addr &&

            (start_addr + size <= mem->start_addr + mem->memory_size) &&

            (phys_offset - start_addr == mem->phys_offset - mem->start_addr)) {

            /* The new slot fits into the existing one and comes with

             * identical parameters - nothing to be done. */

            return;

        }

        old = *mem;

        /* unregister the overlapping slot */

        mem->memory_size = 0;

        err = kvm_set_user_memory_region(s, mem);

        if (err) {

            fprintf(stderr, "%s: error unregistering overlapping slot: %s\n",

                    __func__, strerror(-err));

            abort();

        }

        /* Workaround for older KVM versions: we can't join slots, even not by

         * unregistering the previous ones and then registering the larger

         * slot. We have to maintain the existing fragmentation. Sigh.

         *

         * This workaround assumes that the new slot starts at the same

         * address as the first existing one. If not or if some overlapping

         * slot comes around later, we will fail (not seen in practice so far)

         * - and actually require a recent KVM version. */

        if (old.start_addr == start_addr && old.memory_size < size &&

            flags < IO_MEM_UNASSIGNED) {

            mem = kvm_alloc_slot(s);

            mem->memory_size = old.memory_size;

            mem->start_addr = old.start_addr;

            mem->phys_offset = old.phys_offset;

            mem->flags = 0;

            err = kvm_set_user_memory_region(s, mem);

            if (err) {

                fprintf(stderr, "%s: error updating slot: %s\n", __func__,

                        strerror(-err));

                abort();

            }

            start_addr += old.memory_size;

            phys_offset += old.memory_size;

            size -= old.memory_size;

            continue;

        }

        /* register prefix slot */

        if (old.start_addr < start_addr) {

            mem = kvm_alloc_slot(s);

            mem->memory_size = start_addr - old.start_addr;

            mem->start_addr = old.start_addr;

            mem->phys_offset = old.phys_offset;

            mem->flags = 0;

            err = kvm_set_user_memory_region(s, mem);

            if (err) {

                fprintf(stderr, "%s: error registering prefix slot: %s\n",

                        __func__, strerror(-err));

                abort();

            }

        }

        /* register suffix slot */

        if (old.start_addr + old.memory_size > start_addr + size) {

            ram_addr_t size_delta;

            mem = kvm_alloc_slot(s);

            mem->start_addr = start_addr + size;

            size_delta = mem->start_addr - old.start_addr;

            mem->memory_size = old.memory_size - size_delta;

            mem->phys_offset = old.phys_offset + size_delta;

            mem->flags = 0;

            err = kvm_set_user_memory_region(s, mem);

            if (err) {

                fprintf(stderr, "%s: error registering suffix slot: %s\n",

                        __func__, strerror(-err));

                abort();

            }

        }

    }

    /* in case the KVM bug workaround already "consumed" the new slot */

    if (!size)

        return;

    /* KVM does not need to know about this memory */

    if (flags >= IO_MEM_UNASSIGNED)

        return;

    mem = kvm_alloc_slot(s);

    mem->memory_size = size;

    mem->start_addr = start_addr;

    mem->phys_offset = phys_offset;

    mem->flags = 0;

    err = kvm_set_user_memory_region(s, mem);

    if (err) {

        fprintf(stderr, "%s: error registering slot: %s\n", __func__,

                strerror(-err));

        abort();

    }

}

int kvm_ioctl(KVMState *s, int type, ...)

{

    int ret;

    void *arg;

    va_list ap;

    va_start(ap, type);

    arg = va_arg(ap, void *);

    va_end(ap);

    ret = ioctl(s->fd, type, arg);

    if (ret == -1)

        ret = -errno;

    return ret;

}

int kvm_vm_ioctl(KVMState *s, int type, ...)

{

    int ret;

    void *arg;

    va_list ap;

    va_start(ap, type);

    arg = va_arg(ap, void *);

    va_end(ap);

    ret = ioctl(s->vmfd, type, arg);

    if (ret == -1)

        ret = -errno;

    return ret;

}

int kvm_vcpu_ioctl(CPUState *env, int type, ...)

{

    int ret;

    void *arg;

    va_list ap;

    va_start(ap, type);

    arg = va_arg(ap, void *);

    va_end(ap);

    ret = ioctl(env->kvm_fd, type, arg);

    if (ret == -1)

        ret = -errno;

    return ret;

}

int kvm_has_sync_mmu(void)

{

#ifdef KVM_CAP_SYNC_MMU

    KVMState *s = kvm_state;

    if (kvm_ioctl(s, KVM_CHECK_EXTENSION, KVM_CAP_SYNC_MMU) > 0)

        return 1;

#endif

    return 0;

}

#ifdef KVM_CAP_SET_GUEST_DEBUG

struct kvm_sw_breakpoint *kvm_find_sw_breakpoint(CPUState *env,

                                                 target_ulong pc)

{

    struct kvm_sw_breakpoint *bp;

    TAILQ_FOREACH(bp, &env->kvm_state->kvm_sw_breakpoints, entry) {

        if (bp->pc == pc)

            return bp;

    }

    return NULL;

}

int kvm_sw_breakpoints_active(CPUState *env)

{

    return !TAILQ_EMPTY(&env->kvm_state->kvm_sw_breakpoints);

}

int kvm_update_guest_debug(CPUState *env, unsigned long reinject_trap)

{

    struct kvm_guest_debug dbg;

    dbg.control = 0;

    if (env->singlestep_enabled)

        dbg.control = KVM_GUESTDBG_ENABLE | KVM_GUESTDBG_SINGLESTEP;

    kvm_arch_update_guest_debug(env, &dbg);

    dbg.control |= reinject_trap;

    return kvm_vcpu_ioctl(env, KVM_SET_GUEST_DEBUG, &dbg);

}

int kvm_insert_breakpoint(CPUState *current_env, target_ulong addr,

                          target_ulong len, int type)

{

    struct kvm_sw_breakpoint *bp;

    CPUState *env;

    int err;

    if (type == GDB_BREAKPOINT_SW) {

        bp = kvm_find_sw_breakpoint(current_env, addr);

        if (bp) {

            bp->use_count++;

            return 0;

        }

        bp = qemu_malloc(sizeof(struct kvm_sw_breakpoint));

        if (!bp)

            return -ENOMEM;

        bp->pc = addr;

        bp->use_count = 1;

        err = kvm_arch_insert_sw_breakpoint(current_env, bp);

        if (err) {

            free(bp);

            return err;

        }

        TAILQ_INSERT_HEAD(&current_env->kvm_state->kvm_sw_breakpoints,

                          bp, entry);

    } else {

        err = kvm_arch_insert_hw_breakpoint(addr, len, type);

        if (err)

            return err;

    }

    for (env = first_cpu; env != NULL; env = env->next_cpu) {

        err = kvm_update_guest_debug(env, 0);

        if (err)

            return err;

    }

    return 0;

}

int kvm_remove_breakpoint(CPUState *current_env, target_ulong addr,

                          target_ulong len, int type)

{

    struct kvm_sw_breakpoint *bp;

    CPUState *env;

    int err;

    if (type == GDB_BREAKPOINT_SW) {

        bp = kvm_find_sw_breakpoint(current_env, addr);

        if (!bp)

            return -ENOENT;

        if (bp->use_count > 1) {

            bp->use_count--;

            return 0;

        }

        err = kvm_arch_remove_sw_breakpoint(current_env, bp);

        if (err)

            return err;

        TAILQ_REMOVE(&current_env->kvm_state->kvm_sw_breakpoints, bp, entry);

        qemu_free(bp);

    } else {

        err = kvm_arch_remove_hw_breakpoint(addr, len, type);

        if (err)

            return err;

    }

    for (env = first_cpu; env != NULL; env = env->next_cpu) {

        err = kvm_update_guest_debug(env, 0);

        if (err)

            return err;

    }

    return 0;

}

void kvm_remove_all_breakpoints(CPUState *current_env)

{

    struct kvm_sw_breakpoint *bp, *next;

    KVMState *s = current_env->kvm_state;

    CPUState *env;

    TAILQ_FOREACH_SAFE(bp, &s->kvm_sw_breakpoints, entry, next) {

        if (kvm_arch_remove_sw_breakpoint(current_env, bp) != 0) {

            /* Try harder to find a CPU that currently sees the breakpoint. */

            for (env = first_cpu; env != NULL; env = env->next_cpu) {

                if (kvm_arch_remove_sw_breakpoint(env, bp) == 0)

                    break;

            }

        }

    }

    kvm_arch_remove_all_hw_breakpoints();

    for (env = first_cpu; env != NULL; env = env->next_cpu)

        kvm_update_guest_debug(env, 0);

}

#else /* !KVM_CAP_SET_GUEST_DEBUG */

int kvm_update_guest_debug(CPUState *env, unsigned long reinject_trap)

{

    return -EINVAL;

}

int kvm_insert_breakpoint(CPUState *current_env, target_ulong addr,

                          target_ulong len, int type)

{

    return -EINVAL;

}

int kvm_remove_breakpoint(CPUState *current_env, target_ulong addr,

                          target_ulong len, int type)

{

    return -EINVAL;

}

void kvm_remove_all_breakpoints(CPUState *current_env)

{

}

#endif /* !KVM_CAP_SET_GUEST_DEBUG */