dump: Move the code to dump/

Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Message-Id: <20190619201050.19040-16-armbru@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>

1 files changed, 2071 insertions, 0 deletions

diff --git a/dump/dump.c b/dump/dump.c
new file mode 100644
index 0000000000..c7b2301652
--- /dev/null
+++ b/dump/dump.c
@@ -0,0 +1,2071 @@
+/*
+ * QEMU dump
+ *
+ * Copyright Fujitsu, Corp. 2011, 2012
+ *
+ * Authors:
+ *     Wen Congyang <wency@cn.fujitsu.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 "qemu/osdep.h"
+#include "qemu-common.h"
+#include "qemu/cutils.h"
+#include "elf.h"
+#include "cpu.h"
+#include "exec/hwaddr.h"
+#include "monitor/monitor.h"
+#include "sysemu/kvm.h"
+#include "sysemu/dump.h"
+#include "sysemu/sysemu.h"
+#include "sysemu/memory_mapping.h"
+#include "sysemu/cpus.h"
+#include "qapi/error.h"
+#include "qapi/qapi-commands-dump.h"
+#include "qapi/qapi-events-dump.h"
+#include "qapi/qmp/qerror.h"
+#include "qemu/error-report.h"
+#include "hw/misc/vmcoreinfo.h"
+
+#ifdef TARGET_X86_64
+#include "win_dump.h"
+#endif
+
+#include <zlib.h>
+#ifdef CONFIG_LZO
+#include <lzo/lzo1x.h>
+#endif
+#ifdef CONFIG_SNAPPY
+#include <snappy-c.h>
+#endif
+#ifndef ELF_MACHINE_UNAME
+#define ELF_MACHINE_UNAME "Unknown"
+#endif
+
+#define MAX_GUEST_NOTE_SIZE (1 << 20) /* 1MB should be enough */
+
+#define ELF_NOTE_SIZE(hdr_size, name_size, desc_size)   \
+    ((DIV_ROUND_UP((hdr_size), 4) +                     \
+      DIV_ROUND_UP((name_size), 4) +                    \
+      DIV_ROUND_UP((desc_size), 4)) * 4)
+
+uint16_t cpu_to_dump16(DumpState *s, uint16_t val)
+{
+    if (s->dump_info.d_endian == ELFDATA2LSB) {
+        val = cpu_to_le16(val);
+    } else {
+        val = cpu_to_be16(val);
+    }
+
+    return val;
+}
+
+uint32_t cpu_to_dump32(DumpState *s, uint32_t val)
+{
+    if (s->dump_info.d_endian == ELFDATA2LSB) {
+        val = cpu_to_le32(val);
+    } else {
+        val = cpu_to_be32(val);
+    }
+
+    return val;
+}
+
+uint64_t cpu_to_dump64(DumpState *s, uint64_t val)
+{
+    if (s->dump_info.d_endian == ELFDATA2LSB) {
+        val = cpu_to_le64(val);
+    } else {
+        val = cpu_to_be64(val);
+    }
+
+    return val;
+}
+
+static int dump_cleanup(DumpState *s)
+{
+    guest_phys_blocks_free(&s->guest_phys_blocks);
+    memory_mapping_list_free(&s->list);
+    close(s->fd);
+    g_free(s->guest_note);
+    s->guest_note = NULL;
+    if (s->resume) {
+        if (s->detached) {
+            qemu_mutex_lock_iothread();
+        }
+        vm_start();
+        if (s->detached) {
+            qemu_mutex_unlock_iothread();
+        }
+    }
+
+    return 0;
+}
+
+static int fd_write_vmcore(const void *buf, size_t size, void *opaque)
+{
+    DumpState *s = opaque;
+    size_t written_size;
+
+    written_size = qemu_write_full(s->fd, buf, size);
+    if (written_size != size) {
+        return -errno;
+    }
+
+    return 0;
+}
+
+static void write_elf64_header(DumpState *s, Error **errp)
+{
+    Elf64_Ehdr elf_header;
+    int ret;
+
+    memset(&elf_header, 0, sizeof(Elf64_Ehdr));
+    memcpy(&elf_header, ELFMAG, SELFMAG);
+    elf_header.e_ident[EI_CLASS] = ELFCLASS64;
+    elf_header.e_ident[EI_DATA] = s->dump_info.d_endian;
+    elf_header.e_ident[EI_VERSION] = EV_CURRENT;
+    elf_header.e_type = cpu_to_dump16(s, ET_CORE);
+    elf_header.e_machine = cpu_to_dump16(s, s->dump_info.d_machine);
+    elf_header.e_version = cpu_to_dump32(s, EV_CURRENT);
+    elf_header.e_ehsize = cpu_to_dump16(s, sizeof(elf_header));
+    elf_header.e_phoff = cpu_to_dump64(s, sizeof(Elf64_Ehdr));
+    elf_header.e_phentsize = cpu_to_dump16(s, sizeof(Elf64_Phdr));
+    elf_header.e_phnum = cpu_to_dump16(s, s->phdr_num);
+    if (s->have_section) {
+        uint64_t shoff = sizeof(Elf64_Ehdr) + sizeof(Elf64_Phdr) * s->sh_info;
+
+        elf_header.e_shoff = cpu_to_dump64(s, shoff);
+        elf_header.e_shentsize = cpu_to_dump16(s, sizeof(Elf64_Shdr));
+        elf_header.e_shnum = cpu_to_dump16(s, 1);
+    }
+
+    ret = fd_write_vmcore(&elf_header, sizeof(elf_header), s);
+    if (ret < 0) {
+        error_setg_errno(errp, -ret, "dump: failed to write elf header");
+    }
+}
+
+static void write_elf32_header(DumpState *s, Error **errp)
+{
+    Elf32_Ehdr elf_header;
+    int ret;
+
+    memset(&elf_header, 0, sizeof(Elf32_Ehdr));
+    memcpy(&elf_header, ELFMAG, SELFMAG);
+    elf_header.e_ident[EI_CLASS] = ELFCLASS32;
+    elf_header.e_ident[EI_DATA] = s->dump_info.d_endian;
+    elf_header.e_ident[EI_VERSION] = EV_CURRENT;
+    elf_header.e_type = cpu_to_dump16(s, ET_CORE);
+    elf_header.e_machine = cpu_to_dump16(s, s->dump_info.d_machine);
+    elf_header.e_version = cpu_to_dump32(s, EV_CURRENT);
+    elf_header.e_ehsize = cpu_to_dump16(s, sizeof(elf_header));
+    elf_header.e_phoff = cpu_to_dump32(s, sizeof(Elf32_Ehdr));
+    elf_header.e_phentsize = cpu_to_dump16(s, sizeof(Elf32_Phdr));
+    elf_header.e_phnum = cpu_to_dump16(s, s->phdr_num);
+    if (s->have_section) {
+        uint32_t shoff = sizeof(Elf32_Ehdr) + sizeof(Elf32_Phdr) * s->sh_info;
+
+        elf_header.e_shoff = cpu_to_dump32(s, shoff);
+        elf_header.e_shentsize = cpu_to_dump16(s, sizeof(Elf32_Shdr));
+        elf_header.e_shnum = cpu_to_dump16(s, 1);
+    }
+
+    ret = fd_write_vmcore(&elf_header, sizeof(elf_header), s);
+    if (ret < 0) {
+        error_setg_errno(errp, -ret, "dump: failed to write elf header");
+    }
+}
+
+static void write_elf64_load(DumpState *s, MemoryMapping *memory_mapping,
+                             int phdr_index, hwaddr offset,
+                             hwaddr filesz, Error **errp)
+{
+    Elf64_Phdr phdr;
+    int ret;
+
+    memset(&phdr, 0, sizeof(Elf64_Phdr));
+    phdr.p_type = cpu_to_dump32(s, PT_LOAD);
+    phdr.p_offset = cpu_to_dump64(s, offset);
+    phdr.p_paddr = cpu_to_dump64(s, memory_mapping->phys_addr);
+    phdr.p_filesz = cpu_to_dump64(s, filesz);
+    phdr.p_memsz = cpu_to_dump64(s, memory_mapping->length);
+    phdr.p_vaddr = cpu_to_dump64(s, memory_mapping->virt_addr) ?: phdr.p_paddr;
+
+    assert(memory_mapping->length >= filesz);
+
+    ret = fd_write_vmcore(&phdr, sizeof(Elf64_Phdr), s);
+    if (ret < 0) {
+        error_setg_errno(errp, -ret,
+                         "dump: failed to write program header table");
+    }
+}
+
+static void write_elf32_load(DumpState *s, MemoryMapping *memory_mapping,
+                             int phdr_index, hwaddr offset,
+                             hwaddr filesz, Error **errp)
+{
+    Elf32_Phdr phdr;
+    int ret;
+
+    memset(&phdr, 0, sizeof(Elf32_Phdr));
+    phdr.p_type = cpu_to_dump32(s, PT_LOAD);
+    phdr.p_offset = cpu_to_dump32(s, offset);
+    phdr.p_paddr = cpu_to_dump32(s, memory_mapping->phys_addr);
+    phdr.p_filesz = cpu_to_dump32(s, filesz);
+    phdr.p_memsz = cpu_to_dump32(s, memory_mapping->length);
+    phdr.p_vaddr =
+        cpu_to_dump32(s, memory_mapping->virt_addr) ?: phdr.p_paddr;
+
+    assert(memory_mapping->length >= filesz);
+
+    ret = fd_write_vmcore(&phdr, sizeof(Elf32_Phdr), s);
+    if (ret < 0) {
+        error_setg_errno(errp, -ret,
+                         "dump: failed to write program header table");
+    }
+}
+
+static void write_elf64_note(DumpState *s, Error **errp)
+{
+    Elf64_Phdr phdr;
+    hwaddr begin = s->memory_offset - s->note_size;
+    int ret;
+
+    memset(&phdr, 0, sizeof(Elf64_Phdr));
+    phdr.p_type = cpu_to_dump32(s, PT_NOTE);
+    phdr.p_offset = cpu_to_dump64(s, begin);
+    phdr.p_paddr = 0;
+    phdr.p_filesz = cpu_to_dump64(s, s->note_size);
+    phdr.p_memsz = cpu_to_dump64(s, s->note_size);
+    phdr.p_vaddr = 0;
+
+    ret = fd_write_vmcore(&phdr, sizeof(Elf64_Phdr), s);
+    if (ret < 0) {
+        error_setg_errno(errp, -ret,
+                         "dump: failed to write program header table");
+    }
+}
+
+static inline int cpu_index(CPUState *cpu)
+{
+    return cpu->cpu_index + 1;
+}
+
+static void write_guest_note(WriteCoreDumpFunction f, DumpState *s,
+                             Error **errp)
+{
+    int ret;
+
+    if (s->guest_note) {
+        ret = f(s->guest_note, s->guest_note_size, s);
+        if (ret < 0) {
+            error_setg(errp, "dump: failed to write guest note");
+        }
+    }
+}
+
+static void write_elf64_notes(WriteCoreDumpFunction f, DumpState *s,
+                              Error **errp)
+{
+    CPUState *cpu;
+    int ret;
+    int id;
+
+    CPU_FOREACH(cpu) {
+        id = cpu_index(cpu);
+        ret = cpu_write_elf64_note(f, cpu, id, s);
+        if (ret < 0) {
+            error_setg(errp, "dump: failed to write elf notes");
+            return;
+        }
+    }
+
+    CPU_FOREACH(cpu) {
+        ret = cpu_write_elf64_qemunote(f, cpu, s);
+        if (ret < 0) {
+            error_setg(errp, "dump: failed to write CPU status");
+            return;
+        }
+    }
+
+    write_guest_note(f, s, errp);
+}
+
+static void write_elf32_note(DumpState *s, Error **errp)
+{
+    hwaddr begin = s->memory_offset - s->note_size;
+    Elf32_Phdr phdr;
+    int ret;
+
+    memset(&phdr, 0, sizeof(Elf32_Phdr));
+    phdr.p_type = cpu_to_dump32(s, PT_NOTE);
+    phdr.p_offset = cpu_to_dump32(s, begin);
+    phdr.p_paddr = 0;
+    phdr.p_filesz = cpu_to_dump32(s, s->note_size);
+    phdr.p_memsz = cpu_to_dump32(s, s->note_size);
+    phdr.p_vaddr = 0;
+
+    ret = fd_write_vmcore(&phdr, sizeof(Elf32_Phdr), s);
+    if (ret < 0) {
+        error_setg_errno(errp, -ret,
+                         "dump: failed to write program header table");
+    }
+}
+
+static void write_elf32_notes(WriteCoreDumpFunction f, DumpState *s,
+                              Error **errp)
+{
+    CPUState *cpu;
+    int ret;
+    int id;
+
+    CPU_FOREACH(cpu) {
+        id = cpu_index(cpu);
+        ret = cpu_write_elf32_note(f, cpu, id, s);
+        if (ret < 0) {
+            error_setg(errp, "dump: failed to write elf notes");
+            return;
+        }
+    }
+
+    CPU_FOREACH(cpu) {
+        ret = cpu_write_elf32_qemunote(f, cpu, s);
+        if (ret < 0) {
+            error_setg(errp, "dump: failed to write CPU status");
+            return;
+        }
+    }
+
+    write_guest_note(f, s, errp);
+}
+
+static void write_elf_section(DumpState *s, int type, Error **errp)
+{
+    Elf32_Shdr shdr32;
+    Elf64_Shdr shdr64;
+    int shdr_size;
+    void *shdr;
+    int ret;
+
+    if (type == 0) {
+        shdr_size = sizeof(Elf32_Shdr);
+        memset(&shdr32, 0, shdr_size);
+        shdr32.sh_info = cpu_to_dump32(s, s->sh_info);
+        shdr = &shdr32;
+    } else {
+        shdr_size = sizeof(Elf64_Shdr);
+        memset(&shdr64, 0, shdr_size);
+        shdr64.sh_info = cpu_to_dump32(s, s->sh_info);
+        shdr = &shdr64;
+    }
+
+    ret = fd_write_vmcore(&shdr, shdr_size, s);
+    if (ret < 0) {
+        error_setg_errno(errp, -ret,
+                         "dump: failed to write section header table");
+    }
+}
+
+static void write_data(DumpState *s, void *buf, int length, Error **errp)
+{
+    int ret;
+
+    ret = fd_write_vmcore(buf, length, s);
+    if (ret < 0) {
+        error_setg_errno(errp, -ret, "dump: failed to save memory");
+    } else {
+        s->written_size += length;
+    }
+}
+
+/* write the memory to vmcore. 1 page per I/O. */
+static void write_memory(DumpState *s, GuestPhysBlock *block, ram_addr_t start,
+                         int64_t size, Error **errp)
+{
+    int64_t i;
+    Error *local_err = NULL;
+
+    for (i = 0; i < size / s->dump_info.page_size; i++) {
+        write_data(s, block->host_addr + start + i * s->dump_info.page_size,
+                   s->dump_info.page_size, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            return;
+        }
+    }
+
+    if ((size % s->dump_info.page_size) != 0) {
+        write_data(s, block->host_addr + start + i * s->dump_info.page_size,
+                   size % s->dump_info.page_size, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            return;
+        }
+    }
+}
+
+/* get the memory's offset and size in the vmcore */
+static void get_offset_range(hwaddr phys_addr,
+                             ram_addr_t mapping_length,
+                             DumpState *s,
+                             hwaddr *p_offset,
+                             hwaddr *p_filesz)
+{
+    GuestPhysBlock *block;
+    hwaddr offset = s->memory_offset;
+    int64_t size_in_block, start;
+
+    /* When the memory is not stored into vmcore, offset will be -1 */
+    *p_offset = -1;
+    *p_filesz = 0;
+
+    if (s->has_filter) {
+        if (phys_addr < s->begin || phys_addr >= s->begin + s->length) {
+            return;
+        }
+    }
+
+    QTAILQ_FOREACH(block, &s->guest_phys_blocks.head, next) {
+        if (s->has_filter) {
+            if (block->target_start >= s->begin + s->length ||
+                block->target_end <= s->begin) {
+                /* This block is out of the range */
+                continue;
+            }
+
+            if (s->begin <= block->target_start) {
+                start = block->target_start;
+            } else {
+                start = s->begin;
+            }
+
+            size_in_block = block->target_end - start;
+            if (s->begin + s->length < block->target_end) {
+                size_in_block -= block->target_end - (s->begin + s->length);
+            }
+        } else {
+            start = block->target_start;
+            size_in_block = block->target_end - block->target_start;
+        }
+
+        if (phys_addr >= start && phys_addr < start + size_in_block) {
+            *p_offset = phys_addr - start + offset;
+
+            /* The offset range mapped from the vmcore file must not spill over
+             * the GuestPhysBlock, clamp it. The rest of the mapping will be
+             * zero-filled in memory at load time; see
+             * <http://refspecs.linuxbase.org/elf/gabi4+/ch5.pheader.html>.
+             */
+            *p_filesz = phys_addr + mapping_length <= start + size_in_block ?
+                        mapping_length :
+                        size_in_block - (phys_addr - start);
+            return;
+        }
+
+        offset += size_in_block;
+    }
+}
+
+static void write_elf_loads(DumpState *s, Error **errp)
+{
+    hwaddr offset, filesz;
+    MemoryMapping *memory_mapping;
+    uint32_t phdr_index = 1;
+    uint32_t max_index;
+    Error *local_err = NULL;
+
+    if (s->have_section) {
+        max_index = s->sh_info;
+    } else {
+        max_index = s->phdr_num;
+    }
+
+    QTAILQ_FOREACH(memory_mapping, &s->list.head, next) {
+        get_offset_range(memory_mapping->phys_addr,
+                         memory_mapping->length,
+                         s, &offset, &filesz);
+        if (s->dump_info.d_class == ELFCLASS64) {
+            write_elf64_load(s, memory_mapping, phdr_index++, offset,
+                             filesz, &local_err);
+        } else {
+            write_elf32_load(s, memory_mapping, phdr_index++, offset,
+                             filesz, &local_err);
+        }
+
+        if (local_err) {
+            error_propagate(errp, local_err);
+            return;
+        }
+
+        if (phdr_index >= max_index) {
+            break;
+        }
+    }
+}
+
+/* write elf header, PT_NOTE and elf note to vmcore. */
+static void dump_begin(DumpState *s, Error **errp)
+{
+    Error *local_err = NULL;
+
+    /*
+     * the vmcore's format is:
+     *   --------------
+     *   |  elf header |
+     *   --------------
+     *   |  PT_NOTE    |
+     *   --------------
+     *   |  PT_LOAD    |
+     *   --------------
+     *   |  ......     |
+     *   --------------
+     *   |  PT_LOAD    |
+     *   --------------
+     *   |  sec_hdr    |
+     *   --------------
+     *   |  elf note   |
+     *   --------------
+     *   |  memory     |
+     *   --------------
+     *
+     * we only know where the memory is saved after we write elf note into
+     * vmcore.
+     */
+
+    /* write elf header to vmcore */
+    if (s->dump_info.d_class == ELFCLASS64) {
+        write_elf64_header(s, &local_err);
+    } else {
+        write_elf32_header(s, &local_err);
+    }
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
+    }
+
+    if (s->dump_info.d_class == ELFCLASS64) {
+        /* write PT_NOTE to vmcore */
+        write_elf64_note(s, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            return;
+        }
+
+        /* write all PT_LOAD to vmcore */
+        write_elf_loads(s, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            return;
+        }
+
+        /* write section to vmcore */
+        if (s->have_section) {
+            write_elf_section(s, 1, &local_err);
+            if (local_err) {
+                error_propagate(errp, local_err);
+                return;
+            }
+        }
+
+        /* write notes to vmcore */
+        write_elf64_notes(fd_write_vmcore, s, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            return;
+        }
+    } else {
+        /* write PT_NOTE to vmcore */
+        write_elf32_note(s, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            return;
+        }
+
+        /* write all PT_LOAD to vmcore */
+        write_elf_loads(s, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            return;
+        }
+
+        /* write section to vmcore */
+        if (s->have_section) {
+            write_elf_section(s, 0, &local_err);
+            if (local_err) {
+                error_propagate(errp, local_err);
+                return;
+            }
+        }
+
+        /* write notes to vmcore */
+        write_elf32_notes(fd_write_vmcore, s, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            return;
+        }
+    }
+}
+
+static int get_next_block(DumpState *s, GuestPhysBlock *block)
+{
+    while (1) {
+        block = QTAILQ_NEXT(block, next);
+        if (!block) {
+            /* no more block */
+            return 1;
+        }
+
+        s->start = 0;
+        s->next_block = block;
+        if (s->has_filter) {
+            if (block->target_start >= s->begin + s->length ||
+                block->target_end <= s->begin) {
+                /* This block is out of the range */
+                continue;
+            }
+
+            if (s->begin > block->target_start) {
+                s->start = s->begin - block->target_start;
+            }
+        }
+
+        return 0;
+    }
+}
+
+/* write all memory to vmcore */
+static void dump_iterate(DumpState *s, Error **errp)
+{
+    GuestPhysBlock *block;
+    int64_t size;
+    Error *local_err = NULL;
+
+    do {
+        block = s->next_block;
+
+        size = block->target_end - block->target_start;
+        if (s->has_filter) {
+            size -= s->start;
+            if (s->begin + s->length < block->target_end) {
+                size -= block->target_end - (s->begin + s->length);
+            }
+        }
+        write_memory(s, block, s->start, size, &local_err);
+        if (local_err) {
+            error_propagate(errp, local_err);
+            return;
+        }
+
+    } while (!get_next_block(s, block));
+}
+
+static void create_vmcore(DumpState *s, Error **errp)
+{
+    Error *local_err = NULL;
+
+    dump_begin(s, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
+    }
+
+    dump_iterate(s, errp);
+}
+
+static int write_start_flat_header(int fd)
+{
+    MakedumpfileHeader *mh;
+    int ret = 0;
+
+    QEMU_BUILD_BUG_ON(sizeof *mh > MAX_SIZE_MDF_HEADER);
+    mh = g_malloc0(MAX_SIZE_MDF_HEADER);
+
+    memcpy(mh->signature, MAKEDUMPFILE_SIGNATURE,
+           MIN(sizeof mh->signature, sizeof MAKEDUMPFILE_SIGNATURE));
+
+    mh->type = cpu_to_be64(TYPE_FLAT_HEADER);
+    mh->version = cpu_to_be64(VERSION_FLAT_HEADER);
+
+    size_t written_size;
+    written_size = qemu_write_full(fd, mh, MAX_SIZE_MDF_HEADER);
+    if (written_size != MAX_SIZE_MDF_HEADER) {
+        ret = -1;
+    }
+
+    g_free(mh);
+    return ret;
+}
+
+static int write_end_flat_header(int fd)
+{
+    MakedumpfileDataHeader mdh;
+
+    mdh.offset = END_FLAG_FLAT_HEADER;
+    mdh.buf_size = END_FLAG_FLAT_HEADER;
+
+    size_t written_size;
+    written_size = qemu_write_full(fd, &mdh, sizeof(mdh));
+    if (written_size != sizeof(mdh)) {
+        return -1;
+    }
+
+    return 0;
+}
+
+static int write_buffer(int fd, off_t offset, const void *buf, size_t size)
+{
+    size_t written_size;
+    MakedumpfileDataHeader mdh;
+
+    mdh.offset = cpu_to_be64(offset);
+    mdh.buf_size = cpu_to_be64(size);
+
+    written_size = qemu_write_full(fd, &mdh, sizeof(mdh));
+    if (written_size != sizeof(mdh)) {
+        return -1;
+    }
+
+    written_size = qemu_write_full(fd, buf, size);
+    if (written_size != size) {
+        return -1;
+    }
+
+    return 0;
+}
+
+static int buf_write_note(const void *buf, size_t size, void *opaque)
+{
+    DumpState *s = opaque;
+
+    /* note_buf is not enough */
+    if (s->note_buf_offset + size > s->note_size) {
+        return -1;
+    }
+
+    memcpy(s->note_buf + s->note_buf_offset, buf, size);
+
+    s->note_buf_offset += size;
+
+    return 0;
+}
+
+/*
+ * This function retrieves various sizes from an elf header.
+ *
+ * @note has to be a valid ELF note. The return sizes are unmodified
+ * (not padded or rounded up to be multiple of 4).
+ */
+static void get_note_sizes(DumpState *s, const void *note,
+                           uint64_t *note_head_size,
+                           uint64_t *name_size,
+                           uint64_t *desc_size)
+{
+    uint64_t note_head_sz;
+    uint64_t name_sz;
+    uint64_t desc_sz;
+
+    if (s->dump_info.d_class == ELFCLASS64) {
+        const Elf64_Nhdr *hdr = note;
+        note_head_sz = sizeof(Elf64_Nhdr);
+        name_sz = tswap64(hdr->n_namesz);
+        desc_sz = tswap64(hdr->n_descsz);
+    } else {
+        const Elf32_Nhdr *hdr = note;
+        note_head_sz = sizeof(Elf32_Nhdr);
+        name_sz = tswap32(hdr->n_namesz);
+        desc_sz = tswap32(hdr->n_descsz);
+    }
+
+    if (note_head_size) {
+        *note_head_size = note_head_sz;
+    }
+    if (name_size) {
+        *name_size = name_sz;
+    }
+    if (desc_size) {
+        *desc_size = desc_sz;
+    }
+}
+
+static bool note_name_equal(DumpState *s,
+                            const uint8_t *note, const char *name)
+{
+    int len = strlen(name) + 1;
+    uint64_t head_size, name_size;
+
+    get_note_sizes(s, note, &head_size, &name_size, NULL);
+    head_size = ROUND_UP(head_size, 4);
+
+    return name_size == len && memcmp(note + head_size, name, len) == 0;
+}
+
+/* write common header, sub header and elf note to vmcore */
+static void create_header32(DumpState *s, Error **errp)
+{
+    DiskDumpHeader32 *dh = NULL;
+    KdumpSubHeader32 *kh = NULL;
+    size_t size;
+    uint32_t block_size;
+    uint32_t sub_hdr_size;
+    uint32_t bitmap_blocks;
+    uint32_t status = 0;
+    uint64_t offset_note;
+    Error *local_err = NULL;
+
+    /* write common header, the version of kdump-compressed format is 6th */
+    size = sizeof(DiskDumpHeader32);
+    dh = g_malloc0(size);
+
+    memcpy(dh->signature, KDUMP_SIGNATURE, SIG_LEN);
+    dh->header_version = cpu_to_dump32(s, 6);
+    block_size = s->dump_info.page_size;
+    dh->block_size = cpu_to_dump32(s, block_size);
+    sub_hdr_size = sizeof(struct KdumpSubHeader32) + s->note_size;
+    sub_hdr_size = DIV_ROUND_UP(sub_hdr_size, block_size);
+    dh->sub_hdr_size = cpu_to_dump32(s, sub_hdr_size);
+    /* dh->max_mapnr may be truncated, full 64bit is in kh.max_mapnr_64 */
+    dh->max_mapnr = cpu_to_dump32(s, MIN(s->max_mapnr, UINT_MAX));
+    dh->nr_cpus = cpu_to_dump32(s, s->nr_cpus);
+    bitmap_blocks = DIV_ROUND_UP(s->len_dump_bitmap, block_size) * 2;
+    dh->bitmap_blocks = cpu_to_dump32(s, bitmap_blocks);
+    strncpy(dh->utsname.machine, ELF_MACHINE_UNAME, sizeof(dh->utsname.machine));
+
+    if (s->flag_compress & DUMP_DH_COMPRESSED_ZLIB) {
+        status |= DUMP_DH_COMPRESSED_ZLIB;
+    }
+#ifdef CONFIG_LZO
+    if (s->flag_compress & DUMP_DH_COMPRESSED_LZO) {
+        status |= DUMP_DH_COMPRESSED_LZO;
+    }
+#endif
+#ifdef CONFIG_SNAPPY
+    if (s->flag_compress & DUMP_DH_COMPRESSED_SNAPPY) {
+        status |= DUMP_DH_COMPRESSED_SNAPPY;
+    }
+#endif
+    dh->status = cpu_to_dump32(s, status);
+
+    if (write_buffer(s->fd, 0, dh, size) < 0) {
+        error_setg(errp, "dump: failed to write disk dump header");
+        goto out;
+    }
+
+    /* write sub header */
+    size = sizeof(KdumpSubHeader32);
+    kh = g_malloc0(size);
+
+    /* 64bit max_mapnr_64 */
+    kh->max_mapnr_64 = cpu_to_dump64(s, s->max_mapnr);
+    kh->phys_base = cpu_to_dump32(s, s->dump_info.phys_base);
+    kh->dump_level = cpu_to_dump32(s, DUMP_LEVEL);
+
+    offset_note = DISKDUMP_HEADER_BLOCKS * block_size + size;
+    if (s->guest_note &&
+        note_name_equal(s, s->guest_note, "VMCOREINFO")) {
+        uint64_t hsize, name_size, size_vmcoreinfo_desc, offset_vmcoreinfo;
+
+        get_note_sizes(s, s->guest_note,
+                       &hsize, &name_size, &size_vmcoreinfo_desc);
+        offset_vmcoreinfo = offset_note + s->note_size - s->guest_note_size +
+            (DIV_ROUND_UP(hsize, 4) + DIV_ROUND_UP(name_size, 4)) * 4;
+        kh->offset_vmcoreinfo = cpu_to_dump64(s, offset_vmcoreinfo);
+        kh->size_vmcoreinfo = cpu_to_dump32(s, size_vmcoreinfo_desc);
+    }
+
+    kh->offset_note = cpu_to_dump64(s, offset_note);
+    kh->note_size = cpu_to_dump32(s, s->note_size);
+
+    if (write_buffer(s->fd, DISKDUMP_HEADER_BLOCKS *
+                     block_size, kh, size) < 0) {
+        error_setg(errp, "dump: failed to write kdump sub header");
+        goto out;
+    }
+
+    /* write note */
+    s->note_buf = g_malloc0(s->note_size);
+    s->note_buf_offset = 0;
+
+    /* use s->note_buf to store notes temporarily */
+    write_elf32_notes(buf_write_note, s, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        goto out;
+    }
+    if (write_buffer(s->fd, offset_note, s->note_buf,
+                     s->note_size) < 0) {
+        error_setg(errp, "dump: failed to write notes");
+        goto out;
+    }
+
+    /* get offset of dump_bitmap */
+    s->offset_dump_bitmap = (DISKDUMP_HEADER_BLOCKS + sub_hdr_size) *
+                             block_size;
+
+    /* get offset of page */
+    s->offset_page = (DISKDUMP_HEADER_BLOCKS + sub_hdr_size + bitmap_blocks) *
+                     block_size;
+
+out:
+    g_free(dh);
+    g_free(kh);
+    g_free(s->note_buf);
+}
+
+/* write common header, sub header and elf note to vmcore */
+static void create_header64(DumpState *s, Error **errp)
+{
+    DiskDumpHeader64 *dh = NULL;
+    KdumpSubHeader64 *kh = NULL;
+    size_t size;
+    uint32_t block_size;
+    uint32_t sub_hdr_size;
+    uint32_t bitmap_blocks;
+    uint32_t status = 0;
+    uint64_t offset_note;
+    Error *local_err = NULL;
+
+    /* write common header, the version of kdump-compressed format is 6th */
+    size = sizeof(DiskDumpHeader64);
+    dh = g_malloc0(size);
+
+    memcpy(dh->signature, KDUMP_SIGNATURE, SIG_LEN);
+    dh->header_version = cpu_to_dump32(s, 6);
+    block_size = s->dump_info.page_size;
+    dh->block_size = cpu_to_dump32(s, block_size);
+    sub_hdr_size = sizeof(struct KdumpSubHeader64) + s->note_size;
+    sub_hdr_size = DIV_ROUND_UP(sub_hdr_size, block_size);
+    dh->sub_hdr_size = cpu_to_dump32(s, sub_hdr_size);
+    /* dh->max_mapnr may be truncated, full 64bit is in kh.max_mapnr_64 */
+    dh->max_mapnr = cpu_to_dump32(s, MIN(s->max_mapnr, UINT_MAX));
+    dh->nr_cpus = cpu_to_dump32(s, s->nr_cpus);
+    bitmap_blocks = DIV_ROUND_UP(s->len_dump_bitmap, block_size) * 2;
+    dh->bitmap_blocks = cpu_to_dump32(s, bitmap_blocks);
+    strncpy(dh->utsname.machine, ELF_MACHINE_UNAME, sizeof(dh->utsname.machine));
+
+    if (s->flag_compress & DUMP_DH_COMPRESSED_ZLIB) {
+        status |= DUMP_DH_COMPRESSED_ZLIB;
+    }
+#ifdef CONFIG_LZO
+    if (s->flag_compress & DUMP_DH_COMPRESSED_LZO) {
+        status |= DUMP_DH_COMPRESSED_LZO;
+    }
+#endif
+#ifdef CONFIG_SNAPPY
+    if (s->flag_compress & DUMP_DH_COMPRESSED_SNAPPY) {
+        status |= DUMP_DH_COMPRESSED_SNAPPY;
+    }
+#endif
+    dh->status = cpu_to_dump32(s, status);
+
+    if (write_buffer(s->fd, 0, dh, size) < 0) {
+        error_setg(errp, "dump: failed to write disk dump header");
+        goto out;
+    }
+
+    /* write sub header */
+    size = sizeof(KdumpSubHeader64);
+    kh = g_malloc0(size);
+
+    /* 64bit max_mapnr_64 */
+    kh->max_mapnr_64 = cpu_to_dump64(s, s->max_mapnr);
+    kh->phys_base = cpu_to_dump64(s, s->dump_info.phys_base);
+    kh->dump_level = cpu_to_dump32(s, DUMP_LEVEL);
+
+    offset_note = DISKDUMP_HEADER_BLOCKS * block_size + size;
+    if (s->guest_note &&
+        note_name_equal(s, s->guest_note, "VMCOREINFO")) {
+        uint64_t hsize, name_size, size_vmcoreinfo_desc, offset_vmcoreinfo;
+
+        get_note_sizes(s, s->guest_note,
+                       &hsize, &name_size, &size_vmcoreinfo_desc);
+        offset_vmcoreinfo = offset_note + s->note_size - s->guest_note_size +
+            (DIV_ROUND_UP(hsize, 4) + DIV_ROUND_UP(name_size, 4)) * 4;
+        kh->offset_vmcoreinfo = cpu_to_dump64(s, offset_vmcoreinfo);
+        kh->size_vmcoreinfo = cpu_to_dump64(s, size_vmcoreinfo_desc);
+    }
+
+    kh->offset_note = cpu_to_dump64(s, offset_note);
+    kh->note_size = cpu_to_dump64(s, s->note_size);
+
+    if (write_buffer(s->fd, DISKDUMP_HEADER_BLOCKS *
+                     block_size, kh, size) < 0) {
+        error_setg(errp, "dump: failed to write kdump sub header");
+        goto out;
+    }
+
+    /* write note */
+    s->note_buf = g_malloc0(s->note_size);
+    s->note_buf_offset = 0;
+
+    /* use s->note_buf to store notes temporarily */
+    write_elf64_notes(buf_write_note, s, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        goto out;
+    }
+
+    if (write_buffer(s->fd, offset_note, s->note_buf,
+                     s->note_size) < 0) {
+        error_setg(errp, "dump: failed to write notes");
+        goto out;
+    }
+
+    /* get offset of dump_bitmap */
+    s->offset_dump_bitmap = (DISKDUMP_HEADER_BLOCKS + sub_hdr_size) *
+                             block_size;
+
+    /* get offset of page */
+    s->offset_page = (DISKDUMP_HEADER_BLOCKS + sub_hdr_size + bitmap_blocks) *
+                     block_size;
+
+out:
+    g_free(dh);
+    g_free(kh);
+    g_free(s->note_buf);
+}
+
+static void write_dump_header(DumpState *s, Error **errp)
+{
+     Error *local_err = NULL;
+
+    if (s->dump_info.d_class == ELFCLASS32) {
+        create_header32(s, &local_err);
+    } else {
+        create_header64(s, &local_err);
+    }
+    error_propagate(errp, local_err);
+}
+
+static size_t dump_bitmap_get_bufsize(DumpState *s)
+{
+    return s->dump_info.page_size;
+}
+
+/*
+ * set dump_bitmap sequencely. the bit before last_pfn is not allowed to be
+ * rewritten, so if need to set the first bit, set last_pfn and pfn to 0.
+ * set_dump_bitmap will always leave the recently set bit un-sync. And setting
+ * (last bit + sizeof(buf) * 8) to 0 will do flushing the content in buf into
+ * vmcore, ie. synchronizing un-sync bit into vmcore.
+ */
+static int set_dump_bitmap(uint64_t last_pfn, uint64_t pfn, bool value,
+                           uint8_t *buf, DumpState *s)
+{
+    off_t old_offset, new_offset;
+    off_t offset_bitmap1, offset_bitmap2;
+    uint32_t byte, bit;
+    size_t bitmap_bufsize = dump_bitmap_get_bufsize(s);
+    size_t bits_per_buf = bitmap_bufsize * CHAR_BIT;
+
+    /* should not set the previous place */
+    assert(last_pfn <= pfn);
+
+    /*
+     * if the bit needed to be set is not cached in buf, flush the data in buf
+     * to vmcore firstly.
+     * making new_offset be bigger than old_offset can also sync remained data
+     * into vmcore.
+     */
+    old_offset = bitmap_bufsize * (last_pfn / bits_per_buf);
+    new_offset = bitmap_bufsize * (pfn / bits_per_buf);
+
+    while (old_offset < new_offset) {
+        /* calculate the offset and write dump_bitmap */
+        offset_bitmap1 = s->offset_dump_bitmap + old_offset;
+        if (write_buffer(s->fd, offset_bitmap1, buf,
+                         bitmap_bufsize) < 0) {
+            return -1;
+        }
+
+        /* dump level 1 is chosen, so 1st and 2nd bitmap are same */
+        offset_bitmap2 = s->offset_dump_bitmap + s->len_dump_bitmap +
+                         old_offset;
+        if (write_buffer(s->fd, offset_bitmap2, buf,
+                         bitmap_bufsize) < 0) {
+            return -1;
+        }
+
+        memset(buf, 0, bitmap_bufsize);
+        old_offset += bitmap_bufsize;
+    }
+
+    /* get the exact place of the bit in the buf, and set it */
+    byte = (pfn % bits_per_buf) / CHAR_BIT;
+    bit = (pfn % bits_per_buf) % CHAR_BIT;
+    if (value) {
+        buf[byte] |= 1u << bit;
+    } else {
+        buf[byte] &= ~(1u << bit);
+    }
+
+    return 0;
+}
+
+static uint64_t dump_paddr_to_pfn(DumpState *s, uint64_t addr)
+{
+    int target_page_shift = ctz32(s->dump_info.page_size);
+
+    return (addr >> target_page_shift) - ARCH_PFN_OFFSET;
+}
+
+static uint64_t dump_pfn_to_paddr(DumpState *s, uint64_t pfn)
+{
+    int target_page_shift = ctz32(s->dump_info.page_size);
+
+    return (pfn + ARCH_PFN_OFFSET) << target_page_shift;
+}
+
+/*
+ * exam every page and return the page frame number and the address of the page.
+ * bufptr can be NULL. note: the blocks here is supposed to reflect guest-phys
+ * blocks, so block->target_start and block->target_end should be interal
+ * multiples of the target page size.
+ */
+static bool get_next_page(GuestPhysBlock **blockptr, uint64_t *pfnptr,
+                          uint8_t **bufptr, DumpState *s)
+{
+    GuestPhysBlock *block = *blockptr;
+    hwaddr addr, target_page_mask = ~((hwaddr)s->dump_info.page_size - 1);
+    uint8_t *buf;
+
+    /* block == NULL means the start of the iteration */
+    if (!block) {
+        block = QTAILQ_FIRST(&s->guest_phys_blocks.head);
+        *blockptr = block;
+        assert((block->target_start & ~target_page_mask) == 0);
+        assert((block->target_end & ~target_page_mask) == 0);
+        *pfnptr = dump_paddr_to_pfn(s, block->target_start);
+        if (bufptr) {
+            *bufptr = block->host_addr;
+        }
+        return true;
+    }
+
+    *pfnptr = *pfnptr + 1;
+    addr = dump_pfn_to_paddr(s, *pfnptr);
+
+    if ((addr >= block->target_start) &&
+        (addr + s->dump_info.page_size <= block->target_end)) {
+        buf = block->host_addr + (addr - block->target_start);
+    } else {
+        /* the next page is in the next block */
+        block = QTAILQ_NEXT(block, next);
+        *blockptr = block;
+        if (!block) {
+            return false;
+        }
+        assert((block->target_start & ~target_page_mask) == 0);
+        assert((block->target_end & ~target_page_mask) == 0);
+        *pfnptr = dump_paddr_to_pfn(s, block->target_start);
+        buf = block->host_addr;
+    }
+
+    if (bufptr) {
+        *bufptr = buf;
+    }
+
+    return true;
+}
+
+static void write_dump_bitmap(DumpState *s, Error **errp)
+{
+    int ret = 0;
+    uint64_t last_pfn, pfn;
+    void *dump_bitmap_buf;
+    size_t num_dumpable;
+    GuestPhysBlock *block_iter = NULL;
+    size_t bitmap_bufsize = dump_bitmap_get_bufsize(s);
+    size_t bits_per_buf = bitmap_bufsize * CHAR_BIT;
+
+    /* dump_bitmap_buf is used to store dump_bitmap temporarily */
+    dump_bitmap_buf = g_malloc0(bitmap_bufsize);
+
+    num_dumpable = 0;
+    last_pfn = 0;
+
+    /*
+     * exam memory page by page, and set the bit in dump_bitmap corresponded
+     * to the existing page.
+     */
+    while (get_next_page(&block_iter, &pfn, NULL, s)) {
+        ret = set_dump_bitmap(last_pfn, pfn, true, dump_bitmap_buf, s);
+        if (ret < 0) {
+            error_setg(errp, "dump: failed to set dump_bitmap");
+            goto out;
+        }
+
+        last_pfn = pfn;
+        num_dumpable++;
+    }
+
+    /*
+     * set_dump_bitmap will always leave the recently set bit un-sync. Here we
+     * set the remaining bits from last_pfn to the end of the bitmap buffer to
+     * 0. With those set, the un-sync bit will be synchronized into the vmcore.
+     */
+    if (num_dumpable > 0) {
+        ret = set_dump_bitmap(last_pfn, last_pfn + bits_per_buf, false,
+                              dump_bitmap_buf, s);
+        if (ret < 0) {
+            error_setg(errp, "dump: failed to sync dump_bitmap");
+            goto out;
+        }
+    }
+
+    /* number of dumpable pages that will be dumped later */
+    s->num_dumpable = num_dumpable;
+
+out:
+    g_free(dump_bitmap_buf);
+}
+
+static void prepare_data_cache(DataCache *data_cache, DumpState *s,
+                               off_t offset)
+{
+    data_cache->fd = s->fd;
+    data_cache->data_size = 0;
+    data_cache->buf_size = 4 * dump_bitmap_get_bufsize(s);
+    data_cache->buf = g_malloc0(data_cache->buf_size);
+    data_cache->offset = offset;
+}
+
+static int write_cache(DataCache *dc, const void *buf, size_t size,
+                       bool flag_sync)
+{
+    /*
+     * dc->buf_size should not be less than size, otherwise dc will never be
+     * enough
+     */
+    assert(size <= dc->buf_size);
+
+    /*
+     * if flag_sync is set, synchronize data in dc->buf into vmcore.
+     * otherwise check if the space is enough for caching data in buf, if not,
+     * write the data in dc->buf to dc->fd and reset dc->buf
+     */
+    if ((!flag_sync && dc->data_size + size > dc->buf_size) ||
+        (flag_sync && dc->data_size > 0)) {
+        if (write_buffer(dc->fd, dc->offset, dc->buf, dc->data_size) < 0) {
+            return -1;
+        }
+
+        dc->offset += dc->data_size;
+        dc->data_size = 0;
+    }
+
+    if (!flag_sync) {
+        memcpy(dc->buf + dc->data_size, buf, size);
+        dc->data_size += size;
+    }
+
+    return 0;
+}
+
+static void free_data_cache(DataCache *data_cache)
+{
+    g_free(data_cache->buf);
+}
+
+static size_t get_len_buf_out(size_t page_size, uint32_t flag_compress)
+{
+    switch (flag_compress) {
+    case DUMP_DH_COMPRESSED_ZLIB:
+        return compressBound(page_size);
+
+    case DUMP_DH_COMPRESSED_LZO:
+        /*
+         * LZO will expand incompressible data by a little amount. Please check
+         * the following URL to see the expansion calculation:
+         * http://www.oberhumer.com/opensource/lzo/lzofaq.php
+         */
+        return page_size + page_size / 16 + 64 + 3;
+
+#ifdef CONFIG_SNAPPY
+    case DUMP_DH_COMPRESSED_SNAPPY:
+        return snappy_max_compressed_length(page_size);
+#endif
+    }
+    return 0;
+}
+
+/*
+ * check if the page is all 0
+ */
+static inline bool is_zero_page(const uint8_t *buf, size_t page_size)
+{
+    return buffer_is_zero(buf, page_size);
+}
+
+static void write_dump_pages(DumpState *s, Error **errp)
+{
+    int ret = 0;
+    DataCache page_desc, page_data;
+    size_t len_buf_out, size_out;
+#ifdef CONFIG_LZO
+    lzo_bytep wrkmem = NULL;
+#endif
+    uint8_t *buf_out = NULL;
+    off_t offset_desc, offset_data;
+    PageDescriptor pd, pd_zero;
+    uint8_t *buf;
+    GuestPhysBlock *block_iter = NULL;
+    uint64_t pfn_iter;
+
+    /* get offset of page_desc and page_data in dump file */
+    offset_desc = s->offset_page;
+    offset_data = offset_desc + sizeof(PageDescriptor) * s->num_dumpable;
+
+    prepare_data_cache(&page_desc, s, offset_desc);
+    prepare_data_cache(&page_data, s, offset_data);
+
+    /* prepare buffer to store compressed data */
+    len_buf_out = get_len_buf_out(s->dump_info.page_size, s->flag_compress);
+    assert(len_buf_out != 0);
+
+#ifdef CONFIG_LZO
+    wrkmem = g_malloc(LZO1X_1_MEM_COMPRESS);
+#endif
+
+    buf_out = g_malloc(len_buf_out);
+
+    /*
+     * init zero page's page_desc and page_data, because every zero page
+     * uses the same page_data
+     */
+    pd_zero.size = cpu_to_dump32(s, s->dump_info.page_size);
+    pd_zero.flags = cpu_to_dump32(s, 0);
+    pd_zero.offset = cpu_to_dump64(s, offset_data);
+    pd_zero.page_flags = cpu_to_dump64(s, 0);
+    buf = g_malloc0(s->dump_info.page_size);
+    ret = write_cache(&page_data, buf, s->dump_info.page_size, false);
+    g_free(buf);
+    if (ret < 0) {
+        error_setg(errp, "dump: failed to write page data (zero page)");
+        goto out;
+    }
+
+    offset_data += s->dump_info.page_size;
+
+    /*
+     * dump memory to vmcore page by page. zero page will all be resided in the
+     * first page of page section
+     */
+    while (get_next_page(&block_iter, &pfn_iter, &buf, s)) {
+        /* check zero page */
+        if (is_zero_page(buf, s->dump_info.page_size)) {
+            ret = write_cache(&page_desc, &pd_zero, sizeof(PageDescriptor),
+                              false);
+            if (ret < 0) {
+                error_setg(errp, "dump: failed to write page desc");
+                goto out;
+            }
+        } else {
+            /*
+             * not zero page, then:
+             * 1. compress the page
+             * 2. write the compressed page into the cache of page_data
+             * 3. get page desc of the compressed page and write it into the
+             *    cache of page_desc
+             *
+             * only one compression format will be used here, for
+             * s->flag_compress is set. But when compression fails to work,
+             * we fall back to save in plaintext.
+             */
+             size_out = len_buf_out;
+             if ((s->flag_compress & DUMP_DH_COMPRESSED_ZLIB) &&
+                    (compress2(buf_out, (uLongf *)&size_out, buf,
+                               s->dump_info.page_size, Z_BEST_SPEED) == Z_OK) &&
+                    (size_out < s->dump_info.page_size)) {
+                pd.flags = cpu_to_dump32(s, DUMP_DH_COMPRESSED_ZLIB);
+                pd.size  = cpu_to_dump32(s, size_out);
+
+                ret = write_cache(&page_data, buf_out, size_out, false);
+                if (ret < 0) {
+                    error_setg(errp, "dump: failed to write page data");
+                    goto out;
+                }
+#ifdef CONFIG_LZO
+            } else if ((s->flag_compress & DUMP_DH_COMPRESSED_LZO) &&
+                    (lzo1x_1_compress(buf, s->dump_info.page_size, buf_out,
+                    (lzo_uint *)&size_out, wrkmem) == LZO_E_OK) &&
+                    (size_out < s->dump_info.page_size)) {
+                pd.flags = cpu_to_dump32(s, DUMP_DH_COMPRESSED_LZO);
+                pd.size  = cpu_to_dump32(s, size_out);
+
+                ret = write_cache(&page_data, buf_out, size_out, false);
+                if (ret < 0) {
+                    error_setg(errp, "dump: failed to write page data");
+                    goto out;
+                }
+#endif
+#ifdef CONFIG_SNAPPY
+            } else if ((s->flag_compress & DUMP_DH_COMPRESSED_SNAPPY) &&
+                    (snappy_compress((char *)buf, s->dump_info.page_size,
+                    (char *)buf_out, &size_out) == SNAPPY_OK) &&
+                    (size_out < s->dump_info.page_size)) {
+                pd.flags = cpu_to_dump32(s, DUMP_DH_COMPRESSED_SNAPPY);
+                pd.size  = cpu_to_dump32(s, size_out);
+
+                ret = write_cache(&page_data, buf_out, size_out, false);
+                if (ret < 0) {
+                    error_setg(errp, "dump: failed to write page data");
+                    goto out;
+                }
+#endif
+            } else {
+                /*
+                 * fall back to save in plaintext, size_out should be
+                 * assigned the target's page size
+                 */
+                pd.flags = cpu_to_dump32(s, 0);
+                size_out = s->dump_info.page_size;
+                pd.size = cpu_to_dump32(s, size_out);
+
+                ret = write_cache(&page_data, buf,
+                                  s->dump_info.page_size, false);
+                if (ret < 0) {
+                    error_setg(errp, "dump: failed to write page data");
+                    goto out;
+                }
+            }
+
+            /* get and write page desc here */
+            pd.page_flags = cpu_to_dump64(s, 0);
+            pd.offset = cpu_to_dump64(s, offset_data);
+            offset_data += size_out;
+
+            ret = write_cache(&page_desc, &pd, sizeof(PageDescriptor), false);
+            if (ret < 0) {
+                error_setg(errp, "dump: failed to write page desc");
+                goto out;
+            }
+        }
+        s->written_size += s->dump_info.page_size;
+    }
+
+    ret = write_cache(&page_desc, NULL, 0, true);
+    if (ret < 0) {
+        error_setg(errp, "dump: failed to sync cache for page_desc");
+        goto out;
+    }
+    ret = write_cache(&page_data, NULL, 0, true);
+    if (ret < 0) {
+        error_setg(errp, "dump: failed to sync cache for page_data");
+        goto out;
+    }
+
+out:
+    free_data_cache(&page_desc);
+    free_data_cache(&page_data);
+
+#ifdef CONFIG_LZO
+    g_free(wrkmem);
+#endif
+
+    g_free(buf_out);
+}
+
+static void create_kdump_vmcore(DumpState *s, Error **errp)
+{
+    int ret;
+    Error *local_err = NULL;
+
+    /*
+     * the kdump-compressed format is:
+     *                                               File offset
+     *  +------------------------------------------+ 0x0
+     *  |    main header (struct disk_dump_header) |
+     *  |------------------------------------------+ block 1
+     *  |    sub header (struct kdump_sub_header)  |
+     *  |------------------------------------------+ block 2
+     *  |            1st-dump_bitmap               |
+     *  |------------------------------------------+ block 2 + X blocks
+     *  |            2nd-dump_bitmap               | (aligned by block)
+     *  |------------------------------------------+ block 2 + 2 * X blocks
+     *  |  page desc for pfn 0 (struct page_desc)  | (aligned by block)
+     *  |  page desc for pfn 1 (struct page_desc)  |
+     *  |                    :                     |
+     *  |------------------------------------------| (not aligned by block)
+     *  |         page data (pfn 0)                |
+     *  |         page data (pfn 1)                |
+     *  |                    :                     |
+     *  +------------------------------------------+
+     */
+
+    ret = write_start_flat_header(s->fd);
+    if (ret < 0) {
+        error_setg(errp, "dump: failed to write start flat header");
+        return;
+    }
+
+    write_dump_header(s, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
+    }
+
+    write_dump_bitmap(s, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
+    }
+
+    write_dump_pages(s, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        return;
+    }
+
+    ret = write_end_flat_header(s->fd);
+    if (ret < 0) {
+        error_setg(errp, "dump: failed to write end flat header");
+        return;
+    }
+}
+
+static ram_addr_t get_start_block(DumpState *s)
+{
+    GuestPhysBlock *block;
+
+    if (!s->has_filter) {
+        s->next_block = QTAILQ_FIRST(&s->guest_phys_blocks.head);
+        return 0;
+    }
+
+    QTAILQ_FOREACH(block, &s->guest_phys_blocks.head, next) {
+        if (block->target_start >= s->begin + s->length ||
+            block->target_end <= s->begin) {
+            /* This block is out of the range */
+            continue;
+        }
+
+        s->next_block = block;
+        if (s->begin > block->target_start) {
+            s->start = s->begin - block->target_start;
+        } else {
+            s->start = 0;
+        }
+        return s->start;
+    }
+
+    return -1;
+}
+
+static void get_max_mapnr(DumpState *s)
+{
+    GuestPhysBlock *last_block;
+
+    last_block = QTAILQ_LAST(&s->guest_phys_blocks.head);
+    s->max_mapnr = dump_paddr_to_pfn(s, last_block->target_end);
+}
+
+static DumpState dump_state_global = { .status = DUMP_STATUS_NONE };
+
+static void dump_state_prepare(DumpState *s)
+{
+    /* zero the struct, setting status to active */
+    *s = (DumpState) { .status = DUMP_STATUS_ACTIVE };
+}
+
+bool dump_in_progress(void)
+{
+    DumpState *state = &dump_state_global;
+    return (atomic_read(&state->status) == DUMP_STATUS_ACTIVE);
+}
+
+/* calculate total size of memory to be dumped (taking filter into
+ * acoount.) */
+static int64_t dump_calculate_size(DumpState *s)
+{
+    GuestPhysBlock *block;
+    int64_t size = 0, total = 0, left = 0, right = 0;
+
+    QTAILQ_FOREACH(block, &s->guest_phys_blocks.head, next) {
+        if (s->has_filter) {
+            /* calculate the overlapped region. */
+            left = MAX(s->begin, block->target_start);
+            right = MIN(s->begin + s->length, block->target_end);
+            size = right - left;
+            size = size > 0 ? size : 0;
+        } else {
+            /* count the whole region in */
+            size = (block->target_end - block->target_start);
+        }
+        total += size;
+    }
+
+    return total;
+}
+
+static void vmcoreinfo_update_phys_base(DumpState *s)
+{
+    uint64_t size, note_head_size, name_size, phys_base;
+    char **lines;
+    uint8_t *vmci;
+    size_t i;
+
+    if (!note_name_equal(s, s->guest_note, "VMCOREINFO")) {
+        return;
+    }
+
+    get_note_sizes(s, s->guest_note, &note_head_size, &name_size, &size);
+    note_head_size = ROUND_UP(note_head_size, 4);
+
+    vmci = s->guest_note + note_head_size + ROUND_UP(name_size, 4);
+    *(vmci + size) = '\0';
+
+    lines = g_strsplit((char *)vmci, "\n", -1);
+    for (i = 0; lines[i]; i++) {
+        const char *prefix = NULL;
+
+        if (s->dump_info.d_machine == EM_X86_64) {
+            prefix = "NUMBER(phys_base)=";
+        } else if (s->dump_info.d_machine == EM_AARCH64) {
+            prefix = "NUMBER(PHYS_OFFSET)=";
+        }
+
+        if (prefix && g_str_has_prefix(lines[i], prefix)) {
+            if (qemu_strtou64(lines[i] + strlen(prefix), NULL, 16,
+                              &phys_base) < 0) {
+                warn_report("Failed to read %s", prefix);
+            } else {
+                s->dump_info.phys_base = phys_base;
+            }
+            break;
+        }
+    }
+
+    g_strfreev(lines);
+}
+
+static void dump_init(DumpState *s, int fd, bool has_format,
+                      DumpGuestMemoryFormat format, bool paging, bool has_filter,
+                      int64_t begin, int64_t length, Error **errp)
+{
+    VMCoreInfoState *vmci = vmcoreinfo_find();
+    CPUState *cpu;
+    int nr_cpus;
+    Error *err = NULL;
+    int ret;
+
+    s->has_format = has_format;
+    s->format = format;
+    s->written_size = 0;
+
+    /* kdump-compressed is conflict with paging and filter */
+    if (has_format && format != DUMP_GUEST_MEMORY_FORMAT_ELF) {
+        assert(!paging && !has_filter);
+    }
+
+    if (runstate_is_running()) {
+        vm_stop(RUN_STATE_SAVE_VM);
+        s->resume = true;
+    } else {
+        s->resume = false;
+    }
+
+    /* If we use KVM, we should synchronize the registers before we get dump
+     * info or physmap info.
+     */
+    cpu_synchronize_all_states();
+    nr_cpus = 0;
+    CPU_FOREACH(cpu) {
+        nr_cpus++;
+    }
+
+    s->fd = fd;
+    s->has_filter = has_filter;
+    s->begin = begin;
+    s->length = length;
+
+    memory_mapping_list_init(&s->list);
+
+    guest_phys_blocks_init(&s->guest_phys_blocks);
+    guest_phys_blocks_append(&s->guest_phys_blocks);
+    s->total_size = dump_calculate_size(s);
+#ifdef DEBUG_DUMP_GUEST_MEMORY
+    fprintf(stderr, "DUMP: total memory to dump: %lu\n", s->total_size);
+#endif
+
+    /* it does not make sense to dump non-existent memory */
+    if (!s->total_size) {
+        error_setg(errp, "dump: no guest memory to dump");
+        goto cleanup;
+    }
+
+    s->start = get_start_block(s);
+    if (s->start == -1) {
+        error_setg(errp, QERR_INVALID_PARAMETER, "begin");
+        goto cleanup;
+    }
+
+    /* get dump info: endian, class and architecture.
+     * If the target architecture is not supported, cpu_get_dump_info() will
+     * return -1.
+     */
+    ret = cpu_get_dump_info(&s->dump_info, &s->guest_phys_blocks);
+    if (ret < 0) {
+        error_setg(errp, QERR_UNSUPPORTED);
+        goto cleanup;
+    }
+
+    if (!s->dump_info.page_size) {
+        s->dump_info.page_size = TARGET_PAGE_SIZE;
+    }
+
+    s->note_size = cpu_get_note_size(s->dump_info.d_class,
+                                     s->dump_info.d_machine, nr_cpus);
+    if (s->note_size < 0) {
+        error_setg(errp, QERR_UNSUPPORTED);
+        goto cleanup;
+    }
+
+    /*
+     * The goal of this block is to (a) update the previously guessed
+     * phys_base, (b) copy the guest note out of the guest.
+     * Failure to do so is not fatal for dumping.
+     */
+    if (vmci) {
+        uint64_t addr, note_head_size, name_size, desc_size;
+        uint32_t size;
+        uint16_t format;
+
+        note_head_size = s->dump_info.d_class == ELFCLASS32 ?
+            sizeof(Elf32_Nhdr) : sizeof(Elf64_Nhdr);
+
+        format = le16_to_cpu(vmci->vmcoreinfo.guest_format);
+        size = le32_to_cpu(vmci->vmcoreinfo.size);
+        addr = le64_to_cpu(vmci->vmcoreinfo.paddr);
+        if (!vmci->has_vmcoreinfo) {
+            warn_report("guest note is not present");
+        } else if (size < note_head_size || size > MAX_GUEST_NOTE_SIZE) {
+            warn_report("guest note size is invalid: %" PRIu32, size);
+        } else if (format != FW_CFG_VMCOREINFO_FORMAT_ELF) {
+            warn_report("guest note format is unsupported: %" PRIu16, format);
+        } else {
+            s->guest_note = g_malloc(size + 1); /* +1 for adding \0 */
+            cpu_physical_memory_read(addr, s->guest_note, size);
+
+            get_note_sizes(s, s->guest_note, NULL, &name_size, &desc_size);
+            s->guest_note_size = ELF_NOTE_SIZE(note_head_size, name_size,
+                                               desc_size);
+            if (name_size > MAX_GUEST_NOTE_SIZE ||
+                desc_size > MAX_GUEST_NOTE_SIZE ||
+                s->guest_note_size > size) {
+                warn_report("Invalid guest note header");
+                g_free(s->guest_note);
+                s->guest_note = NULL;
+            } else {
+                vmcoreinfo_update_phys_base(s);
+                s->note_size += s->guest_note_size;
+            }
+        }
+    }
+
+    /* get memory mapping */
+    if (paging) {
+        qemu_get_guest_memory_mapping(&s->list, &s->guest_phys_blocks, &err);
+        if (err != NULL) {
+            error_propagate(errp, err);
+            goto cleanup;
+        }
+    } else {
+        qemu_get_guest_simple_memory_mapping(&s->list, &s->guest_phys_blocks);
+    }
+
+    s->nr_cpus = nr_cpus;
+
+    get_max_mapnr(s);
+
+    uint64_t tmp;
+    tmp = DIV_ROUND_UP(DIV_ROUND_UP(s->max_mapnr, CHAR_BIT),
+                       s->dump_info.page_size);
+    s->len_dump_bitmap = tmp * s->dump_info.page_size;
+
+    /* init for kdump-compressed format */
+    if (has_format && format != DUMP_GUEST_MEMORY_FORMAT_ELF) {
+        switch (format) {
+        case DUMP_GUEST_MEMORY_FORMAT_KDUMP_ZLIB:
+            s->flag_compress = DUMP_DH_COMPRESSED_ZLIB;
+            break;
+
+        case DUMP_GUEST_MEMORY_FORMAT_KDUMP_LZO:
+#ifdef CONFIG_LZO
+            if (lzo_init() != LZO_E_OK) {
+                error_setg(errp, "failed to initialize the LZO library");
+                goto cleanup;
+            }
+#endif
+            s->flag_compress = DUMP_DH_COMPRESSED_LZO;
+            break;
+
+        case DUMP_GUEST_MEMORY_FORMAT_KDUMP_SNAPPY:
+            s->flag_compress = DUMP_DH_COMPRESSED_SNAPPY;
+            break;
+
+        default:
+            s->flag_compress = 0;
+        }
+
+        return;
+    }
+
+    if (s->has_filter) {
+        memory_mapping_filter(&s->list, s->begin, s->length);
+    }
+
+    /*
+     * calculate phdr_num
+     *
+     * the type of ehdr->e_phnum is uint16_t, so we should avoid overflow
+     */
+    s->phdr_num = 1; /* PT_NOTE */
+    if (s->list.num < UINT16_MAX - 2) {
+        s->phdr_num += s->list.num;
+        s->have_section = false;
+    } else {
+        s->have_section = true;
+        s->phdr_num = PN_XNUM;
+        s->sh_info = 1; /* PT_NOTE */
+
+        /* the type of shdr->sh_info is uint32_t, so we should avoid overflow */
+        if (s->list.num <= UINT32_MAX - 1) {
+            s->sh_info += s->list.num;
+        } else {
+            s->sh_info = UINT32_MAX;
+        }
+    }
+
+    if (s->dump_info.d_class == ELFCLASS64) {
+        if (s->have_section) {
+            s->memory_offset = sizeof(Elf64_Ehdr) +
+                               sizeof(Elf64_Phdr) * s->sh_info +
+                               sizeof(Elf64_Shdr) + s->note_size;
+        } else {
+            s->memory_offset = sizeof(Elf64_Ehdr) +
+                               sizeof(Elf64_Phdr) * s->phdr_num + s->note_size;
+        }
+    } else {
+        if (s->have_section) {
+            s->memory_offset = sizeof(Elf32_Ehdr) +
+                               sizeof(Elf32_Phdr) * s->sh_info +
+                               sizeof(Elf32_Shdr) + s->note_size;
+        } else {
+            s->memory_offset = sizeof(Elf32_Ehdr) +
+                               sizeof(Elf32_Phdr) * s->phdr_num + s->note_size;
+        }
+    }
+
+    return;
+
+cleanup:
+    dump_cleanup(s);
+}
+
+/* this operation might be time consuming. */
+static void dump_process(DumpState *s, Error **errp)
+{
+    Error *local_err = NULL;
+    DumpQueryResult *result = NULL;
+
+    if (s->has_format && s->format == DUMP_GUEST_MEMORY_FORMAT_WIN_DMP) {
+#ifdef TARGET_X86_64
+        create_win_dump(s, &local_err);
+#endif
+    } else if (s->has_format && s->format != DUMP_GUEST_MEMORY_FORMAT_ELF) {
+        create_kdump_vmcore(s, &local_err);
+    } else {
+        create_vmcore(s, &local_err);
+    }
+
+    /* make sure status is written after written_size updates */
+    smp_wmb();
+    atomic_set(&s->status,
+               (local_err ? DUMP_STATUS_FAILED : DUMP_STATUS_COMPLETED));
+
+    /* send DUMP_COMPLETED message (unconditionally) */
+    result = qmp_query_dump(NULL);
+    /* should never fail */
+    assert(result);
+    qapi_event_send_dump_completed(result, !!local_err, (local_err ? \
+                                   error_get_pretty(local_err) : NULL));
+    qapi_free_DumpQueryResult(result);
+
+    error_propagate(errp, local_err);
+    dump_cleanup(s);
+}
+
+static void *dump_thread(void *data)
+{
+    DumpState *s = (DumpState *)data;
+    dump_process(s, NULL);
+    return NULL;
+}
+
+DumpQueryResult *qmp_query_dump(Error **errp)
+{
+    DumpQueryResult *result = g_new(DumpQueryResult, 1);
+    DumpState *state = &dump_state_global;
+    result->status = atomic_read(&state->status);
+    /* make sure we are reading status and written_size in order */
+    smp_rmb();
+    result->completed = state->written_size;
+    result->total = state->total_size;
+    return result;
+}
+
+void qmp_dump_guest_memory(bool paging, const char *file,
+                           bool has_detach, bool detach,
+                           bool has_begin, int64_t begin, bool has_length,
+                           int64_t length, bool has_format,
+                           DumpGuestMemoryFormat format, Error **errp)
+{
+    const char *p;
+    int fd = -1;
+    DumpState *s;
+    Error *local_err = NULL;
+    bool detach_p = false;
+
+    if (runstate_check(RUN_STATE_INMIGRATE)) {
+        error_setg(errp, "Dump not allowed during incoming migration.");
+        return;
+    }
+
+    /* if there is a dump in background, we should wait until the dump
+     * finished */
+    if (dump_in_progress()) {
+        error_setg(errp, "There is a dump in process, please wait.");
+        return;
+    }
+
+    /*
+     * kdump-compressed format need the whole memory dumped, so paging or
+     * filter is not supported here.
+     */
+    if ((has_format && format != DUMP_GUEST_MEMORY_FORMAT_ELF) &&
+        (paging || has_begin || has_length)) {
+        error_setg(errp, "kdump-compressed format doesn't support paging or "
+                         "filter");
+        return;
+    }
+    if (has_begin && !has_length) {
+        error_setg(errp, QERR_MISSING_PARAMETER, "length");
+        return;
+    }
+    if (!has_begin && has_length) {
+        error_setg(errp, QERR_MISSING_PARAMETER, "begin");
+        return;
+    }
+    if (has_detach) {
+        detach_p = detach;
+    }
+
+    /* check whether lzo/snappy is supported */
+#ifndef CONFIG_LZO
+    if (has_format && format == DUMP_GUEST_MEMORY_FORMAT_KDUMP_LZO) {
+        error_setg(errp, "kdump-lzo is not available now");
+        return;
+    }
+#endif
+
+#ifndef CONFIG_SNAPPY
+    if (has_format && format == DUMP_GUEST_MEMORY_FORMAT_KDUMP_SNAPPY) {
+        error_setg(errp, "kdump-snappy is not available now");
+        return;
+    }
+#endif
+
+#ifndef TARGET_X86_64
+    if (has_format && format == DUMP_GUEST_MEMORY_FORMAT_WIN_DMP) {
+        error_setg(errp, "Windows dump is only available for x86-64");
+        return;
+    }
+#endif
+
+#if !defined(WIN32)
+    if (strstart(file, "fd:", &p)) {
+        fd = monitor_get_fd(cur_mon, p, errp);
+        if (fd == -1) {
+            return;
+        }
+    }
+#endif
+
+    if  (strstart(file, "file:", &p)) {
+        fd = qemu_open(p, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, S_IRUSR);
+        if (fd < 0) {
+            error_setg_file_open(errp, errno, p);
+            return;
+        }
+    }
+
+    if (fd == -1) {
+        error_setg(errp, QERR_INVALID_PARAMETER, "protocol");
+        return;
+    }
+
+    s = &dump_state_global;
+    dump_state_prepare(s);
+
+    dump_init(s, fd, has_format, format, paging, has_begin,
+              begin, length, &local_err);
+    if (local_err) {
+        error_propagate(errp, local_err);
+        atomic_set(&s->status, DUMP_STATUS_FAILED);
+        return;
+    }
+
+    if (detach_p) {
+        /* detached dump */
+        s->detached = true;
+        qemu_thread_create(&s->dump_thread, "dump_thread", dump_thread,
+                           s, QEMU_THREAD_DETACHED);
+    } else {
+        /* sync dump */
+        dump_process(s, errp);
+    }
+}
+
+DumpGuestMemoryCapability *qmp_query_dump_guest_memory_capability(Error **errp)
+{
+    DumpGuestMemoryFormatList *item;
+    DumpGuestMemoryCapability *cap =
+                                  g_malloc0(sizeof(DumpGuestMemoryCapability));
+
+    /* elf is always available */
+    item = g_malloc0(sizeof(DumpGuestMemoryFormatList));
+    cap->formats = item;
+    item->value = DUMP_GUEST_MEMORY_FORMAT_ELF;
+
+    /* kdump-zlib is always available */
+    item->next = g_malloc0(sizeof(DumpGuestMemoryFormatList));
+    item = item->next;
+    item->value = DUMP_GUEST_MEMORY_FORMAT_KDUMP_ZLIB;
+
+    /* add new item if kdump-lzo is available */
+#ifdef CONFIG_LZO
+    item->next = g_malloc0(sizeof(DumpGuestMemoryFormatList));
+    item = item->next;
+    item->value = DUMP_GUEST_MEMORY_FORMAT_KDUMP_LZO;
+#endif
+
+    /* add new item if kdump-snappy is available */
+#ifdef CONFIG_SNAPPY
+    item->next = g_malloc0(sizeof(DumpGuestMemoryFormatList));
+    item = item->next;
+    item->value = DUMP_GUEST_MEMORY_FORMAT_KDUMP_SNAPPY;
+#endif
+
+    /* Windows dump is available only if target is x86_64 */
+#ifdef TARGET_X86_64
+    item->next = g_malloc0(sizeof(DumpGuestMemoryFormatList));
+    item = item->next;
+    item->value = DUMP_GUEST_MEMORY_FORMAT_WIN_DMP;
+#endif
+
+    return cap;
+}