x86: Enable KVM mode for Android x86 emulator (update/rebase)

This patch enables KVM mode on x86 Linux to boost performance of x86 emulaiton
if the hardware-based virtualization feature is present on the host machine.

Change-Id: I4b24474b3ec115a3b9a7bf017801f4f610253b09
Signed-off-by: Xiaohui Xin <xiaohui.xin@intel.com>
Signed-off-by: Yunhong Jiang <yunhong.jiang@intel.com>
Signed-off-by: Jun Nakajima <jun.nakajima@intel.com>

1 files changed, 1039 insertions, 0 deletions

diff --git a/kvm-all.c b/kvm-all.c
new file mode 100644
index 0000000..f620417
--- /dev/null
+++ b/kvm-all.c
@@ -0,0 +1,1039 @@
+/*
+ * 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 "hw/hw.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;
+    int broken_set_mem_region;
+    int migration_log;
+#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;
+    if (s->migration_log) {
+        mem.flags |= KVM_MEM_LOG_DIRTY_PAGES;
+    }
+    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_put_mp_state(CPUState *env)
+{
+    struct kvm_mp_state mp_state = { .mp_state = env->mp_state };
+
+    return kvm_vcpu_ioctl(env, KVM_SET_MP_STATE, &mp_state);
+}
+
+int kvm_get_mp_state(CPUState *env)
+{
+    struct kvm_mp_state mp_state;
+    int ret;
+
+    ret = kvm_vcpu_ioctl(env, KVM_GET_MP_STATE, &mp_state);
+    if (ret < 0) {
+        return ret;
+    }
+    env->mp_state = mp_state.mp_state;
+    return 0;
+}
+
+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, int flags, int mask)
+{
+    KVMState *s = kvm_state;
+    KVMSlot *mem = kvm_lookup_matching_slot(s, phys_addr, phys_addr + size);
+    int old_flags;
+
+    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;
+    }
+
+    old_flags = mem->flags;
+
+    flags = (mem->flags & ~mask) | flags;
+    mem->flags = flags;
+
+    /* If nothing changed effectively, no need to issue ioctl */
+    if (s->migration_log) {
+        flags |= KVM_MEM_LOG_DIRTY_PAGES;
+    }
+    if (flags == old_flags) {
+            return 0;
+    }
+
+    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);
+}
+
+int kvm_set_migration_log(int enable)
+{
+    KVMState *s = kvm_state;
+    KVMSlot *mem;
+    int i, err;
+
+    s->migration_log = enable;
+
+    for (i = 0; i < ARRAY_SIZE(s->slots); i++) {
+        mem = &s->slots[i];
+
+        if (!!(mem->flags & KVM_MEM_LOG_DIRTY_PAGES) == enable) {
+            continue;
+        }
+        err = kvm_set_user_memory_region(s, mem);
+        if (err) {
+            return err;
+        }
+    }
+    return 0;
+}
+
+/**
+ * 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.
+ */
+int kvm_physical_sync_dirty_bitmap(target_phys_addr_t start_addr,
+                                   target_phys_addr_t end_addr)
+{
+    KVMState *s = kvm_state;
+    unsigned long size, allocated_size = 0;
+    target_phys_addr_t phys_addr;
+    ram_addr_t addr;
+    KVMDirtyLog d;
+    KVMSlot *mem;
+    int ret = 0;
+
+    d.dirty_bitmap = NULL;
+    while (start_addr < end_addr) {
+        mem = kvm_lookup_overlapping_slot(s, start_addr, end_addr);
+        if (mem == NULL) {
+            break;
+        }
+
+        size = ((mem->memory_size >> TARGET_PAGE_BITS) + 7) / 8;
+        if (!d.dirty_bitmap) {
+            d.dirty_bitmap = qemu_malloc(size);
+        } else if (size > allocated_size) {
+            d.dirty_bitmap = qemu_realloc(d.dirty_bitmap, size);
+        }
+        allocated_size = size;
+        memset(d.dirty_bitmap, 0, allocated_size);
+
+        d.slot = mem->slot;
+
+        if (kvm_vm_ioctl(s, KVM_GET_DIRTY_LOG, &d) == -1) {
+            dprintf("ioctl failed %d\n", errno);
+            ret = -1;
+            break;
+        }
+
+        for (phys_addr = mem->start_addr, addr = mem->phys_offset;
+             phys_addr < mem->start_addr + mem->memory_size;
+             phys_addr += TARGET_PAGE_SIZE, addr += TARGET_PAGE_SIZE) {
+            unsigned long *bitmap = (unsigned long *)d.dirty_bitmap;
+            unsigned nr = (phys_addr - mem->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);
+            }
+        }
+        start_addr = phys_addr;
+    }
+    qemu_free(d.dirty_bitmap);
+
+    return ret;
+}
+
+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_check_extension(KVMState *s, unsigned int extension)
+{
+    int ret;
+
+    ret = kvm_ioctl(s, KVM_CHECK_EXTENSION, extension);
+    if (ret < 0) {
+        ret = 0;
+    }
+
+    return ret;
+}
+
+static void kvm_reset_vcpus(void *opaque)
+{
+    kvm_sync_vcpus();
+}
+
+int kvm_init(int smp_cpus)
+{
+    static const char upgrade_note[] =
+        "Please upgrade to at least kernel 2.6.29 or recent kvm-kmod\n"
+        "(see http://sourceforge.net/projects/kvm).\n";
+    KVMState *s;
+    int ret;
+    int i;
+
+    if (smp_cpus > 1) {
+        fprintf(stderr, "No SMP KVM support, use '-smp 1'\n");
+        return -EINVAL;
+    }
+
+    s = qemu_mallocz(sizeof(KVMState));
+
+#ifdef KVM_CAP_SET_GUEST_DEBUG
+    QTAILQ_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.
+     */
+    if (!kvm_check_extension(s, KVM_CAP_USER_MEMORY)) {
+        ret = -EINVAL;
+        fprintf(stderr, "kvm does not support KVM_CAP_USER_MEMORY\n%s",
+                upgrade_note);
+        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. */
+    if (!kvm_check_extension(s, KVM_CAP_DESTROY_MEMORY_REGION_WORKS)) {
+        ret = -EINVAL;
+
+        fprintf(stderr,
+                "KVM kernel module broken (DESTROY_MEMORY_REGION).\n%s",
+                upgrade_note);
+        goto err;
+    }
+
+#ifdef KVM_CAP_COALESCED_MMIO
+    s->coalesced_mmio = kvm_check_extension(s, KVM_CAP_COALESCED_MMIO);
+#else
+    s->coalesced_mmio = 0;
+#endif
+
+    s->broken_set_mem_region = 1;
+#ifdef KVM_CAP_JOIN_MEMORY_REGIONS_WORKS
+    ret = kvm_ioctl(s, KVM_CHECK_EXTENSION, KVM_CAP_JOIN_MEMORY_REGIONS_WORKS);
+    if (ret > 0) {
+        s->broken_set_mem_region = 0;
+    }
+#endif
+
+    ret = kvm_arch_init(s, smp_cpus);
+    if (ret < 0)
+        goto err;
+
+    qemu_register_reset(kvm_reset_vcpus, INT_MAX, NULL);
+
+    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(port));
+                break;
+            case 2:
+                stw_p(ptr, cpu_inw(port));
+                break;
+            case 4:
+                stl_p(ptr, cpu_inl(port));
+                break;
+            }
+        } else {
+            switch (size) {
+            case 1:
+                cpu_outb(port, ldub_p(ptr));
+                break;
+            case 2:
+                cpu_outw(port, lduw_p(ptr));
+                break;
+            case 4:
+                cpu_outl(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 {
+        if (env->exit_request) {
+            dprintf("interrupt exit requested\n");
+            ret = 0;
+            break;
+        }
+
+        kvm_arch_pre_run(env, run);
+        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) {
+        if (flags >= IO_MEM_UNASSIGNED) {
+            if (!kvm_lookup_overlapping_slot(s, start_addr,
+                                             start_addr + size)) {
+                return;
+            }
+            fprintf(stderr, "Unaligned split of a KVM memory slot\n");
+        } else {
+            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 (s->broken_set_mem_region &&
+            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;
+
+    return kvm_check_extension(s, KVM_CAP_SYNC_MMU);
+#else
+    return 0;
+#endif
+}
+
+void kvm_setup_guest_memory(void *start, size_t size)
+{
+    if (!kvm_has_sync_mmu()) {
+#ifdef MADV_DONTFORK
+        int ret = madvise(start, size, MADV_DONTFORK);
+
+        if (ret) {
+            perror("madvice");
+            exit(1);
+        }
+#else
+        fprintf(stderr,
+                "Need MADV_DONTFORK in absence of synchronous KVM MMU\n");
+        exit(1);
+#endif
+    }
+}
+
+#ifdef KVM_CAP_SET_GUEST_DEBUG
+struct kvm_sw_breakpoint *kvm_find_sw_breakpoint(CPUState *env,
+                                                 target_ulong pc)
+{
+    struct kvm_sw_breakpoint *bp;
+
+    QTAILQ_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 !QTAILQ_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;
+        }
+
+        QTAILQ_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;
+
+        QTAILQ_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;
+
+    QTAILQ_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 */