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From 55c524d38cafb5856220c76b9573efa6e22dd1f1 Mon Sep 17 00:00:00 2001
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From: Laszlo Ersek <lersek@redhat.com>
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Date: Fri, 7 Nov 2014 17:18:01 +0100
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Subject: [PATCH 14/41] dump: add API to write dump pages
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Message-id: <1415380693-16593-15-git-send-email-lersek@redhat.com>
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Patchwork-id: 62200
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O-Subject: [RHEL-7.1 qemu-kvm PATCH 14/26] dump: add API to write dump pages
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Bugzilla: 1157798
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RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
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RH-Acked-by: Luiz Capitulino <lcapitulino@redhat.com>
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RH-Acked-by: dgibson <dgibson@redhat.com>
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From: qiaonuohan <qiaonuohan@cn.fujitsu.com>
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functions are used to write page to vmcore. vmcore is written page by page.
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page desc is used to store the information of a page, including a page's size,
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offset, compression format, etc.
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Signed-off-by: Qiao Nuohan <qiaonuohan@cn.fujitsu.com>
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Reviewed-by: Laszlo Ersek <lersek@redhat.com>
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Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
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(cherry picked from commit d12f57ec6640d36e380367a0ab6ab9f3f29b6d51)
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Signed-off-by: Laszlo Ersek <lersek@redhat.com>
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 dump.c                | 231 ++++++++++++++++++++++++++++++++++++++++++++++++++
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 include/sysemu/dump.h |   7 ++
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 2 files changed, 238 insertions(+)
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diff --git a/dump.c b/dump.c
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index 926ab84..fc5530f 100644
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--- a/dump.c
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+++ b/dump.c
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@@ -25,6 +25,14 @@
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 #include "qapi/error.h"
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 #include "qmp-commands.h"
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+#include <zlib.h>
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+#ifdef CONFIG_LZO
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+#include <lzo lzo1x.h="">
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+#endif
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+#ifdef CONFIG_SNAPPY
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+#include <snappy-c.h>
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+#endif
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+
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 static uint16_t cpu_convert_to_target16(uint16_t val, int endian)
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 {
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     if (endian == ELFDATA2LSB) {
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@@ -1218,6 +1226,229 @@ static void free_data_cache(DataCache *data_cache)
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     g_free(data_cache->buf);
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 }
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+static size_t get_len_buf_out(size_t page_size, uint32_t flag_compress)
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+{
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+    size_t len_buf_out_zlib, len_buf_out_lzo, len_buf_out_snappy;
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+    size_t len_buf_out;
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+
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+    /* init buf_out */
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+    len_buf_out_zlib = len_buf_out_lzo = len_buf_out_snappy = 0;
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+
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+    /* buf size for zlib */
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+    len_buf_out_zlib = compressBound(page_size);
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+
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+    /* buf size for lzo */
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+#ifdef CONFIG_LZO
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+    if (flag_compress & DUMP_DH_COMPRESSED_LZO) {
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+        if (lzo_init() != LZO_E_OK) {
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+            /* return 0 to indicate lzo is unavailable */
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+            return 0;
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+        }
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+    }
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+
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+    /*
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+     * LZO will expand incompressible data by a little amount. please check the
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+     * following URL to see the expansion calculation:
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+     * http://www.oberhumer.com/opensource/lzo/lzofaq.php
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+     */
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+    len_buf_out_lzo = page_size + page_size / 16 + 64 + 3;
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+#endif
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+
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+#ifdef CONFIG_SNAPPY
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+    /* buf size for snappy */
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+    len_buf_out_snappy = snappy_max_compressed_length(page_size);
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+#endif
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+
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+    /* get the biggest that can store all kinds of compressed page */
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+    len_buf_out = MAX(len_buf_out_zlib,
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+                      MAX(len_buf_out_lzo, len_buf_out_snappy));
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+
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+    return len_buf_out;
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+}
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+
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+/*
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+ * check if the page is all 0
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+ */
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+static inline bool is_zero_page(const uint8_t *buf, size_t page_size)
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+{
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+    return buffer_is_zero(buf, page_size);
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+}
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+
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+static int write_dump_pages(DumpState *s)
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+{
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+    int ret = 0;
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+    DataCache page_desc, page_data;
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+    size_t len_buf_out, size_out;
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+#ifdef CONFIG_LZO
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+    lzo_bytep wrkmem = NULL;
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+#endif
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+    uint8_t *buf_out = NULL;
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+    off_t offset_desc, offset_data;
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+    PageDescriptor pd, pd_zero;
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+    uint8_t *buf;
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+    int endian = s->dump_info.d_endian;
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+    GuestPhysBlock *block_iter = NULL;
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+    uint64_t pfn_iter;
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+
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+    /* get offset of page_desc and page_data in dump file */
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+    offset_desc = s->offset_page;
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+    offset_data = offset_desc + sizeof(PageDescriptor) * s->num_dumpable;
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+
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+    prepare_data_cache(&page_desc, s, offset_desc);
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+    prepare_data_cache(&page_data, s, offset_data);
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+
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+    /* prepare buffer to store compressed data */
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+    len_buf_out = get_len_buf_out(s->page_size, s->flag_compress);
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+    if (len_buf_out == 0) {
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+        dump_error(s, "dump: failed to get length of output buffer.\n");
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+        goto out;
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+    }
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+
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+#ifdef CONFIG_LZO
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+    wrkmem = g_malloc(LZO1X_1_MEM_COMPRESS);
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+#endif
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+
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+    buf_out = g_malloc(len_buf_out);
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+
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+    /*
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+     * init zero page's page_desc and page_data, because every zero page
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+     * uses the same page_data
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+     */
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+    pd_zero.size = cpu_convert_to_target32(s->page_size, endian);
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+    pd_zero.flags = cpu_convert_to_target32(0, endian);
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+    pd_zero.offset = cpu_convert_to_target64(offset_data, endian);
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+    pd_zero.page_flags = cpu_convert_to_target64(0, endian);
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+    buf = g_malloc0(s->page_size);
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+    ret = write_cache(&page_data, buf, s->page_size, false);
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+    g_free(buf);
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+    if (ret < 0) {
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+        dump_error(s, "dump: failed to write page data(zero page).\n");
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+        goto out;
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+    }
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+
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+    offset_data += s->page_size;
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+
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+    /*
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+     * dump memory to vmcore page by page. zero page will all be resided in the
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+     * first page of page section
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+     */
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+    while (get_next_page(&block_iter, &pfn_iter, &buf, s)) {
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+        /* check zero page */
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+        if (is_zero_page(buf, s->page_size)) {
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+            ret = write_cache(&page_desc, &pd_zero, sizeof(PageDescriptor),
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+                              false);
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+            if (ret < 0) {
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+                dump_error(s, "dump: failed to write page desc.\n");
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+                goto out;
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+            }
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+        } else {
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+            /*
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+             * not zero page, then:
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+             * 1. compress the page
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+             * 2. write the compressed page into the cache of page_data
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+             * 3. get page desc of the compressed page and write it into the
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+             *    cache of page_desc
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+             *
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+             * only one compression format will be used here, for
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+             * s->flag_compress is set. But when compression fails to work,
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+             * we fall back to save in plaintext.
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+             */
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+             size_out = len_buf_out;
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+             if ((s->flag_compress & DUMP_DH_COMPRESSED_ZLIB) &&
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+                    (compress2(buf_out, (uLongf *)&size_out, buf, s->page_size,
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+                    Z_BEST_SPEED) == Z_OK) && (size_out < s->page_size)) {
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+                pd.flags = cpu_convert_to_target32(DUMP_DH_COMPRESSED_ZLIB,
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+                                                   endian);
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+                pd.size  = cpu_convert_to_target32(size_out, endian);
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+
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+                ret = write_cache(&page_data, buf_out, size_out, false);
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+                if (ret < 0) {
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+                    dump_error(s, "dump: failed to write page data.\n");
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+                    goto out;
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+                }
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+#ifdef CONFIG_LZO
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+            } else if ((s->flag_compress & DUMP_DH_COMPRESSED_LZO) &&
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+                    (lzo1x_1_compress(buf, s->page_size, buf_out,
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+                    (lzo_uint *)&size_out, wrkmem) == LZO_E_OK) &&
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+                    (size_out < s->page_size)) {
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+                pd.flags = cpu_convert_to_target32(DUMP_DH_COMPRESSED_LZO,
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+                                                   endian);
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+                pd.size  = cpu_convert_to_target32(size_out, endian);
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+
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+                ret = write_cache(&page_data, buf_out, size_out, false);
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+                if (ret < 0) {
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+                    dump_error(s, "dump: failed to write page data.\n");
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+                    goto out;
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+                }
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+#endif
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+#ifdef CONFIG_SNAPPY
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+            } else if ((s->flag_compress & DUMP_DH_COMPRESSED_SNAPPY) &&
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+                    (snappy_compress((char *)buf, s->page_size,
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+                    (char *)buf_out, &size_out) == SNAPPY_OK) &&
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+                    (size_out < s->page_size)) {
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+                pd.flags = cpu_convert_to_target32(
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+                                        DUMP_DH_COMPRESSED_SNAPPY, endian);
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+                pd.size  = cpu_convert_to_target32(size_out, endian);
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+
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+                ret = write_cache(&page_data, buf_out, size_out, false);
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+                if (ret < 0) {
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+                    dump_error(s, "dump: failed to write page data.\n");
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+                    goto out;
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+                }
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+#endif
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+            } else {
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+                /*
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+                 * fall back to save in plaintext, size_out should be
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+                 * assigned to s->page_size
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+                 */
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+                pd.flags = cpu_convert_to_target32(0, endian);
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+                size_out = s->page_size;
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+                pd.size = cpu_convert_to_target32(size_out, endian);
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+
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+                ret = write_cache(&page_data, buf, s->page_size, false);
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+                if (ret < 0) {
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+                    dump_error(s, "dump: failed to write page data.\n");
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+                    goto out;
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+                }
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+            }
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+
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+            /* get and write page desc here */
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+            pd.page_flags = cpu_convert_to_target64(0, endian);
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+            pd.offset = cpu_convert_to_target64(offset_data, endian);
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+            offset_data += size_out;
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+
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+            ret = write_cache(&page_desc, &pd, sizeof(PageDescriptor), false);
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+            if (ret < 0) {
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+                dump_error(s, "dump: failed to write page desc.\n");
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+                goto out;
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+            }
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+        }
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+    }
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+
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+    ret = write_cache(&page_desc, NULL, 0, true);
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+    if (ret < 0) {
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+        dump_error(s, "dump: failed to sync cache for page_desc.\n");
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+        goto out;
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+    }
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+    ret = write_cache(&page_data, NULL, 0, true);
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+    if (ret < 0) {
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+        dump_error(s, "dump: failed to sync cache for page_data.\n");
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+        goto out;
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+    }
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+
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+out:
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+    free_data_cache(&page_desc);
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+    free_data_cache(&page_data);
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+
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+#ifdef CONFIG_LZO
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+    g_free(wrkmem);
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+#endif
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+
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+    g_free(buf_out);
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+
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+    return ret;
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+}
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+
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 static ram_addr_t get_start_block(DumpState *s)
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 {
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     GuestPhysBlock *block;
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diff --git a/include/sysemu/dump.h b/include/sysemu/dump.h
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index 92a95e4..efab7a3 100644
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--- a/include/sysemu/dump.h
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+++ b/include/sysemu/dump.h
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@@ -151,6 +151,13 @@ typedef struct DataCache {
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     off_t offset;       /* offset of the file */
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 } DataCache;
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+typedef struct QEMU_PACKED PageDescriptor {
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+    uint64_t offset;                /* the offset of the page data*/
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+    uint32_t size;                  /* the size of this dump page */
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+    uint32_t flags;                 /* flags */
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+    uint64_t page_flags;            /* page flags */
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+} PageDescriptor;
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+
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 struct GuestPhysBlockList; /* memory_mapping.h */
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 int cpu_get_dump_info(ArchDumpInfo *info,
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                       const struct GuestPhysBlockList *guest_phys_blocks);
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-- 
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1.8.3.1
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