From 55c524d38cafb5856220c76b9573efa6e22dd1f1 Mon Sep 17 00:00:00 2001

From: Laszlo Ersek <lersek@redhat.com>

Date: Fri, 7 Nov 2014 17:18:01 +0100

Subject: [PATCH 14/41] dump: add API to write dump pages

Message-id: <1415380693-16593-15-git-send-email-lersek@redhat.com>

Patchwork-id: 62200

O-Subject: [RHEL-7.1 qemu-kvm PATCH 14/26] dump: add API to write dump pages

Bugzilla: 1157798

RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>

RH-Acked-by: Luiz Capitulino <lcapitulino@redhat.com>

RH-Acked-by: dgibson <dgibson@redhat.com>

From: qiaonuohan <qiaonuohan@cn.fujitsu.com>

functions are used to write page to vmcore. vmcore is written page by page.

page desc is used to store the information of a page, including a page's size,

offset, compression format, etc.

Signed-off-by: Qiao Nuohan <qiaonuohan@cn.fujitsu.com>

Reviewed-by: Laszlo Ersek <lersek@redhat.com>

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>

(cherry picked from commit d12f57ec6640d36e380367a0ab6ab9f3f29b6d51)

Signed-off-by: Laszlo Ersek <lersek@redhat.com>

Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>

---

 dump.c                | 231 ++++++++++++++++++++++++++++++++++++++++++++++++++

 include/sysemu/dump.h |   7 ++

 2 files changed, 238 insertions(+)

diff --git a/dump.c b/dump.c

index 926ab84..fc5530f 100644

--- a/dump.c

+++ b/dump.c

@@ -25,6 +25,14 @@

 #include "qapi/error.h"

 #include "qmp-commands.h"

+#include <zlib.h>

+#ifdef CONFIG_LZO

+#include <lzo/lzo1x.h>

+#endif

+#ifdef CONFIG_SNAPPY

+#include <snappy-c.h>

+#endif

+

 static uint16_t cpu_convert_to_target16(uint16_t val, int endian)

 {

     if (endian == ELFDATA2LSB) {

@@ -1218,6 +1226,229 @@ 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)

+{

+    size_t len_buf_out_zlib, len_buf_out_lzo, len_buf_out_snappy;

+    size_t len_buf_out;

+

+    /* init buf_out */

+    len_buf_out_zlib = len_buf_out_lzo = len_buf_out_snappy = 0;

+

+    /* buf size for zlib */

+    len_buf_out_zlib = compressBound(page_size);

+

+    /* buf size for lzo */

+#ifdef CONFIG_LZO

+    if (flag_compress & DUMP_DH_COMPRESSED_LZO) {

+        if (lzo_init() != LZO_E_OK) {

+            /* return 0 to indicate lzo is unavailable */

+            return 0;

+        }

+    }

+

+    /*

+     * 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

+     */

+    len_buf_out_lzo = page_size + page_size / 16 + 64 + 3;

+#endif

+

+#ifdef CONFIG_SNAPPY

+    /* buf size for snappy */

+    len_buf_out_snappy = snappy_max_compressed_length(page_size);

+#endif

+

+    /* get the biggest that can store all kinds of compressed page */

+    len_buf_out = MAX(len_buf_out_zlib,

+                      MAX(len_buf_out_lzo, len_buf_out_snappy));

+

+    return len_buf_out;

+}

+

+/*

+ * 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 int write_dump_pages(DumpState *s)

+{

+    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;

+    int endian = s->dump_info.d_endian;

+    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->page_size, s->flag_compress);

+    if (len_buf_out == 0) {

+        dump_error(s, "dump: failed to get length of output buffer.\n");

+        goto out;

+    }

+

+#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_convert_to_target32(s->page_size, endian);

+    pd_zero.flags = cpu_convert_to_target32(0, endian);

+    pd_zero.offset = cpu_convert_to_target64(offset_data, endian);

+    pd_zero.page_flags = cpu_convert_to_target64(0, endian);

+    buf = g_malloc0(s->page_size);

+    ret = write_cache(&page_data, buf, s->page_size, false);

+    g_free(buf);

+    if (ret < 0) {

+        dump_error(s, "dump: failed to write page data(zero page).\n");

+        goto out;

+    }

+

+    offset_data += s->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->page_size)) {

+            ret = write_cache(&page_desc, &pd_zero, sizeof(PageDescriptor),

+                              false);

+            if (ret < 0) {

+                dump_error(s, "dump: failed to write page desc.\n");

+                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->page_size,

+                    Z_BEST_SPEED) == Z_OK) && (size_out < s->page_size)) {

+                pd.flags = cpu_convert_to_target32(DUMP_DH_COMPRESSED_ZLIB,

+                                                   endian);

+                pd.size  = cpu_convert_to_target32(size_out, endian);

+

+                ret = write_cache(&page_data, buf_out, size_out, false);

+                if (ret < 0) {

+                    dump_error(s, "dump: failed to write page data.\n");

+                    goto out;

+                }

+#ifdef CONFIG_LZO

+            } else if ((s->flag_compress & DUMP_DH_COMPRESSED_LZO) &&

+                    (lzo1x_1_compress(buf, s->page_size, buf_out,

+                    (lzo_uint *)&size_out, wrkmem) == LZO_E_OK) &&

+                    (size_out < s->page_size)) {

+                pd.flags = cpu_convert_to_target32(DUMP_DH_COMPRESSED_LZO,

+                                                   endian);

+                pd.size  = cpu_convert_to_target32(size_out, endian);

+

+                ret = write_cache(&page_data, buf_out, size_out, false);

+                if (ret < 0) {

+                    dump_error(s, "dump: failed to write page data.\n");

+                    goto out;

+                }

+#endif

+#ifdef CONFIG_SNAPPY

+            } else if ((s->flag_compress & DUMP_DH_COMPRESSED_SNAPPY) &&

+                    (snappy_compress((char *)buf, s->page_size,

+                    (char *)buf_out, &size_out) == SNAPPY_OK) &&

+                    (size_out < s->page_size)) {

+                pd.flags = cpu_convert_to_target32(

+                                        DUMP_DH_COMPRESSED_SNAPPY, endian);

+                pd.size  = cpu_convert_to_target32(size_out, endian);

+

+                ret = write_cache(&page_data, buf_out, size_out, false);

+                if (ret < 0) {

+                    dump_error(s, "dump: failed to write page data.\n");

+                    goto out;

+                }

+#endif

+            } else {

+                /*

+                 * fall back to save in plaintext, size_out should be

+                 * assigned to s->page_size

+                 */

+                pd.flags = cpu_convert_to_target32(0, endian);

+                size_out = s->page_size;

+                pd.size = cpu_convert_to_target32(size_out, endian);

+

+                ret = write_cache(&page_data, buf, s->page_size, false);

+                if (ret < 0) {

+                    dump_error(s, "dump: failed to write page data.\n");

+                    goto out;

+                }

+            }

+

+            /* get and write page desc here */

+            pd.page_flags = cpu_convert_to_target64(0, endian);

+            pd.offset = cpu_convert_to_target64(offset_data, endian);

+            offset_data += size_out;

+

+            ret = write_cache(&page_desc, &pd, sizeof(PageDescriptor), false);

+            if (ret < 0) {

+                dump_error(s, "dump: failed to write page desc.\n");

+                goto out;

+            }

+        }

+    }

+

+    ret = write_cache(&page_desc, NULL, 0, true);

+    if (ret < 0) {

+        dump_error(s, "dump: failed to sync cache for page_desc.\n");

+        goto out;

+    }

+    ret = write_cache(&page_data, NULL, 0, true);

+    if (ret < 0) {

+        dump_error(s, "dump: failed to sync cache for page_data.\n");

+        goto out;

+    }

+

+out:

+    free_data_cache(&page_desc);

+    free_data_cache(&page_data);

+

+#ifdef CONFIG_LZO

+    g_free(wrkmem);

+#endif

+

+    g_free(buf_out);

+

+    return ret;

+}

+

 static ram_addr_t get_start_block(DumpState *s)

 {

     GuestPhysBlock *block;

diff --git a/include/sysemu/dump.h b/include/sysemu/dump.h

index 92a95e4..efab7a3 100644

--- a/include/sysemu/dump.h

+++ b/include/sysemu/dump.h

@@ -151,6 +151,13 @@ typedef struct DataCache {

     off_t offset;       /* offset of the file */

 } DataCache;

+typedef struct QEMU_PACKED PageDescriptor {

+    uint64_t offset;                /* the offset of the page data*/

+    uint32_t size;                  /* the size of this dump page */

+    uint32_t flags;                 /* flags */

+    uint64_t page_flags;            /* page flags */

+} PageDescriptor;

+

 struct GuestPhysBlockList; /* memory_mapping.h */

 int cpu_get_dump_info(ArchDumpInfo *info,

                       const struct GuestPhysBlockList *guest_phys_blocks);

-- 

1.8.3.1