[Qemu-devel] [PATCH v6 10/11] dump: Make kdump-compressed format available for 'dump-guest-memory'

[Qiao Nuohan]

Make monitor command 'dump-guest-memory' be able to dump in kdump-compressed
format. The command's usage:

  dump [-p] protocol [begin] [length] [format]

'format' is used to specified the format of vmcore and can be:
1. 'elf': ELF format, without compression
2. 'kdump-zlib': kdump-compressed format, with zlib-compressed
3. 'kdump-lzo': kdump-compressed format, with lzo-compressed
4. 'kdump-snappy': kdump-compressed format, with snappy-compressed
And without 'format' being set, it is same as 'elf'.

Note:
  1. The kdump-compressed format is readable only with the crash utility and
     makedumpfile, and it can be smaller than the ELF format because of the
     compression support.
  2. The kdump-compressed format is the 6th edition.

Signed-off-by: Qiao Nuohan <address@hidden>
---
 dump.c           |  163 ++++++++++++++++++++++++++++++++++++++++++++++++++++--
 hmp-commands.hx  |   12 +++-
 hmp.c            |   23 +++++++-
 qapi-schema.json |   22 +++++++-
 qmp-commands.hx  |    6 +-
 5 files changed, 212 insertions(+), 14 deletions(-)

diff --git a/dump.c b/dump.c
index 848957c..b4e79ff 100644
--- a/dump.c
+++ b/dump.c
@@ -1398,6 +1398,70 @@ out:
     return ret;
 }
 
+static int create_kdump_vmcore(DumpState *s)
+{
+    int ret;
+
+    /*
+     * 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)  |
+     *  |                    :                     |
+     *  |  page desc for pfn Z (struct page_desc)  |
+     *  |------------------------------------------| (not aligned by block)
+     *  |         page data (pfn 0)                |
+     *  |         page data (pfn 1)                |
+     *  |                        :                 |
+     *  |         page data (pfn Z)                |
+     *  +------------------------------------------+ offset_eraseinfo
+     *  |                    :                     |
+     *  +------------------------------------------+
+     */
+
+    if (s->flag_flatten) {
+        ret = write_start_flat_header(s->fd);
+        if (ret < 0) {
+            return -1;
+        }
+    }
+
+    ret = write_dump_header(s);
+    if (ret < 0) {
+        return -1;
+    }
+
+    ret = write_dump_bitmap(s);
+    if (ret < 0) {
+        return -1;
+    }
+
+    ret = write_dump_pages(s);
+    if (ret < 0) {
+        return -1;
+    }
+
+    if (s->flag_flatten) {
+        ret = write_end_flat_header(s->fd);
+        if (ret < 0) {
+            return -1;
+        }
+    }
+
+    dump_completed(s);
+
+    return 0;
+}
+
 static ram_addr_t get_start_block(DumpState *s)
 {
     GuestPhysBlock *block;
@@ -1426,7 +1490,27 @@ static ram_addr_t get_start_block(DumpState *s)
     return -1;
 }
 
-static int dump_init(DumpState *s, int fd, bool paging, bool has_filter,
+static bool use_flatten_format(int fd)
+{
+    if (lseek(fd, 0, SEEK_SET) < 0) {
+        return true;
+    }
+
+    return false;
+}
+
+static void get_max_mapnr(DumpState *s)
+{
+    MemoryMapping *memory_mapping;
+
+    QTAILQ_FOREACH(memory_mapping, &s->list.head, next) {
+        s->max_mapnr = paddr_to_pfn(memory_mapping->phys_addr +
+                        memory_mapping->length, s->page_shift);
+    }
+}
+
+static int dump_init(DumpState *s, int fd, bool has_format,
+                     DumpGuestMemoryFormat format, bool paging, bool 
has_filter,
                      int64_t begin, int64_t length, Error **errp)
 {
     CPUState *cpu;
@@ -1494,6 +1578,44 @@ static int dump_init(DumpState *s, int fd, bool paging, 
bool has_filter,
         qemu_get_guest_simple_memory_mapping(&s->list, &s->guest_phys_blocks);
     }
 
+    /* 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:
+            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;
+        }
+
+        /*
+         * check to see if fd is available to seek.
+         * if not, flatten format is used to avoid seek
+         */
+        s->flag_flatten = use_flatten_format(fd);
+
+        s->nr_cpus = nr_cpus;
+        s->page_size = PAGE_SIZE;
+        s->page_shift = ffs(s->page_size) - 1;
+
+        get_max_mapnr(s);
+
+        size_t tmp;
+        tmp = DIV_ROUND_UP(DIV_ROUND_UP(s->max_mapnr, CHAR_BIT), s->page_size);
+        s->len_dump_bitmap = tmp * s->page_size;
+
+        return 0;
+    }
+
     if (s->has_filter) {
         memory_mapping_filter(&s->list, s->begin, s->length);
     }
@@ -1553,8 +1675,9 @@ cleanup:
 }
 
 void qmp_dump_guest_memory(bool paging, const char *file, bool has_begin,
-                           int64_t begin, bool has_length, int64_t length,
-                           Error **errp)
+                           int64_t begin, bool has_length,
+                           int64_t length, bool has_format,
+                           DumpGuestMemoryFormat format, Error **errp)
 {
     const char *p;
     int fd = -1;
@@ -1569,6 +1692,27 @@ void qmp_dump_guest_memory(bool paging, const char 
*file, bool has_begin,
         error_set(errp, QERR_MISSING_PARAMETER, "begin");
         return;
     }
+    /* kdump-compressed format doesn't support paging or filter */
+    if ((has_format && format != DUMP_GUEST_MEMORY_FORMAT_ELF) &&
+        (paging || has_begin || has_length)) {
+        error_set(errp, QERR_INVALID_PARAMETER_COMBINATION);
+        return;
+    }
+
+    /* check whether lzo/snappy is supported */
+#ifndef CONFIG_LZO
+    if (format == DUMP_GUEST_MEMORY_FORMAT_KDUMP_LZO) {
+        error_set(errp, QERR_INVALID_PARAMETER_VALUE, "format",
+                  "supported format(kdump-lzo is not available now)");
+    }
+#endif
+
+#ifndef CONFIG_SNAPPY
+    if (format == DUMP_GUEST_MEMORY_FORMAT_KDUMP_SNAPPY) {
+        error_set(errp, QERR_INVALID_PARAMETER_VALUE, "format",
+                  "supported format(kdump-snappy is not available now)");
+    }
+#endif
 
 #if !defined(WIN32)
     if (strstart(file, "fd:", &p)) {
@@ -1594,14 +1738,21 @@ void qmp_dump_guest_memory(bool paging, const char 
*file, bool has_begin,
 
     s = g_malloc0(sizeof(DumpState));
 
-    ret = dump_init(s, fd, paging, has_begin, begin, length, errp);
+    ret = dump_init(s, fd, has_format, format, paging, has_begin,
+                    begin, length, errp);
     if (ret < 0) {
         g_free(s);
         return;
     }
 
-    if (create_vmcore(s) < 0 && !error_is_set(s->errp)) {
-        error_set(errp, QERR_IO_ERROR);
+    if (has_format && format != DUMP_GUEST_MEMORY_FORMAT_ELF) {
+        if (create_kdump_vmcore(s) < 0 && !error_is_set(s->errp)) {
+            error_set(errp, QERR_IO_ERROR);
+        }
+    } else {
+        if (create_vmcore(s) < 0 && !error_is_set(s->errp)) {
+            error_set(errp, QERR_IO_ERROR);
+        }
     }
 
     g_free(s);
diff --git a/hmp-commands.hx b/hmp-commands.hx
index ebe8e78..3856bb4 100644
--- a/hmp-commands.hx
+++ b/hmp-commands.hx
@@ -993,17 +993,19 @@ ETEXI
 
     {
         .name       = "dump-guest-memory",
-        .args_type  = "paging:-p,filename:F,begin:i?,length:i?",
-        .params     = "[-p] filename [begin] [length]",
+        .args_type  = "paging:-p,filename:F,begin:i?,length:i?,format:s?",
+        .params     = "[-p] filename [begin] [length] [format]",
         .help       = "dump guest memory to file"
                       "\n\t\t\t begin(optional): the starting physical address"
-                      "\n\t\t\t length(optional): the memory size, in bytes",
+                      "\n\t\t\t length(optional): the memory size, in bytes"
+                      "\n\t\t\t format(optional): the format of guest memory 
dump,"
+                      "\n\t\t\t it can be 
elf|kdump-zlib|kdump-lzo|kdump-snappy",
         .mhandler.cmd = hmp_dump_guest_memory,
     },
 
 
 STEXI
address@hidden dump-guest-memory [-p] @var{protocol} @var{begin} @var{length}
address@hidden dump-guest-memory [-p] @var{protocol} @var{begin} @var{length} 
@var{format}
 @findex dump-guest-memory
 Dump guest memory to @var{protocol}. The file can be processed with crash or
 gdb.
@@ -1013,6 +1015,8 @@ gdb.
             specified with length together.
     length: the memory size, in bytes. It's optional, and should be specified
             with begin together.
+    format: the format of guest memory dump. It's optional, and can be
+            elf|kdump-zlib|kdump-lzo|kdump-snappy
 ETEXI
 
     {
diff --git a/hmp.c b/hmp.c
index 32ee285..9bd62b8 100644
--- a/hmp.c
+++ b/hmp.c
@@ -1307,9 +1307,12 @@ void hmp_dump_guest_memory(Monitor *mon, const QDict 
*qdict)
     const char *file = qdict_get_str(qdict, "filename");
     bool has_begin = qdict_haskey(qdict, "begin");
     bool has_length = qdict_haskey(qdict, "length");
+    bool has_format = qdict_haskey(qdict, "format");
     int64_t begin = 0;
     int64_t length = 0;
+    const char *format = NULL;
     char *prot;
+    enum DumpGuestMemoryFormat dump_format;
 
     if (has_begin) {
         begin = qdict_get_int(qdict, "begin");
@@ -1317,11 +1320,29 @@ void hmp_dump_guest_memory(Monitor *mon, const QDict 
*qdict)
     if (has_length) {
         length = qdict_get_int(qdict, "length");
     }
+    if (has_format) {
+        format = qdict_get_str(qdict, "format");
+    }
+
+    if (strcmp(format, "elf") == 0) {
+        dump_format = DUMP_GUEST_MEMORY_FORMAT_ELF;
+    } else if (strcmp(format, "kdump-zlib") == 0) {
+        dump_format = DUMP_GUEST_MEMORY_FORMAT_KDUMP_ZLIB;
+    } else if (strcmp(format, "kdump-lzo") == 0) {
+        dump_format = DUMP_GUEST_MEMORY_FORMAT_KDUMP_LZO;
+    } else if (strcmp(format, "kdump-snappy") == 0) {
+        dump_format = DUMP_GUEST_MEMORY_FORMAT_KDUMP_SNAPPY;
+    } else {
+        error_set(&errp, QERR_INVALID_PARAMETER_VALUE,
+                  "format", "elf|kdump-zlib|kdump-lzo|kdump-snappy");
+        hmp_handle_error(mon, &errp);
+        return;
+    }
 
     prot = g_strconcat("file:", file, NULL);
 
     qmp_dump_guest_memory(paging, prot, has_begin, begin, has_length, length,
-                          &errp);
+                          has_format, dump_format, &errp);
     hmp_handle_error(mon, &errp);
     g_free(prot);
 }
diff --git a/qapi-schema.json b/qapi-schema.json
index c3c939c..19b2b23 100644
--- a/qapi-schema.json
+++ b/qapi-schema.json
@@ -2676,6 +2676,24 @@
 { 'command': 'device_del', 'data': {'id': 'str'} }
 
 ##
+# @DumpGuestMemoryFormat:
+#
+# An enumeration of guest-memory-dump's format.
+#
+# @elf: elf format
+#
+# @kdump-zlib: kdump-compressed format with zlib-compressed
+#
+# @kdump-lzo: kdump-compressed format with zlib-compressed
+#
+# @kdump-snappy: kdump-compressed format with zlib-compressed
+#
+# Since: 1.8
+##
+{ 'enum': 'DumpGuestMemoryFormat',
+  'data': [ 'elf', 'kdump-zlib', 'kdump-lzo', 'kdump-snappy' ] }
+
+##
 # @dump-guest-memory
 #
 # Dump guest's memory to vmcore. It is a synchronous operation that can take
@@ -2711,13 +2729,15 @@
 #          want to dump all guest's memory, please specify the start @begin
 #          and @length
 #
+# @format: #optional if specified, the format of guest memory dump. (since 1.8)
+#
 # Returns: nothing on success
 #
 # Since: 1.2
 ##
 { 'command': 'dump-guest-memory',
   'data': { 'paging': 'bool', 'protocol': 'str', '*begin': 'int',
-            '*length': 'int' } }
+            '*length': 'int', '*format': 'DumpGuestMemoryFormat' } }
 
 ##
 # @netdev_add:
diff --git a/qmp-commands.hx b/qmp-commands.hx
index fba15cd..3de9e7d 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -791,8 +791,8 @@ EQMP
 
     {
         .name       = "dump-guest-memory",
-        .args_type  = "paging:b,protocol:s,begin:i?,end:i?",
-        .params     = "-p protocol [begin] [length]",
+        .args_type  = "paging:b,protocol:s,begin:i?,length:i?,format:s?",
+        .params     = "-p protocol [begin] [length] [format]",
         .help       = "dump guest memory to file",
         .user_print = monitor_user_noop,
         .mhandler.cmd_new = qmp_marshal_input_dump_guest_memory,
@@ -813,6 +813,8 @@ Arguments:
            with length together (json-int)
 - "length": the memory size, in bytes. It's optional, and should be specified
             with begin together (json-int)
+- "format": the format of guest memory dump. It's optional, and can be
+            elf|kdump-zlib|kdump-lzo|kdump-snappy (json-string)
 
 Example:
 
-- 
1.7.1