[PULL 08/26] migration/dirtyrate: Record hash results for each sampled page

["Dr. David Alan Gilbert (git)" <dgilbert@redhat.com>]

From: Chuan Zheng <zhengchuan@huawei.com>

Record hash results for each sampled page, crc32 is taken to calculate
hash results for each sampled length in TARGET_PAGE_SIZE.

Signed-off-by: Chuan Zheng <zhengchuan@huawei.com>
Signed-off-by: YanYing Zhuang <ann.zhuangyanying@huawei.com>
Reviewed-by: David Edmondson <david.edmondson@oracle.com>
Reviewed-by: Li Qiang <liq3ea@gmail.com>
Message-Id: <1600237327-33618-7-git-send-email-zhengchuan@huawei.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 migration/dirtyrate.c | 109 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 109 insertions(+)

diff --git a/migration/dirtyrate.c b/migration/dirtyrate.c
index 10315f7a63..856d26dfe7 100644
--- a/migration/dirtyrate.c
+++ b/migration/dirtyrate.c
@@ -10,6 +10,7 @@
  * See the COPYING file in the top-level directory.
  */
 
+#include <zlib.h>
 #include "qemu/osdep.h"
 #include "qapi/error.h"
 #include "cpu.h"
@@ -68,6 +69,114 @@ static void update_dirtyrate(uint64_t msec)
     DirtyStat.dirty_rate = dirtyrate;
 }
 
+/*
+ * get hash result for the sampled memory with length of TARGET_PAGE_SIZE
+ * in ramblock, which starts from ramblock base address.
+ */
+static uint32_t get_ramblock_vfn_hash(struct RamblockDirtyInfo *info,
+                                      uint64_t vfn)
+{
+    uint32_t crc;
+
+    crc = crc32(0, (info->ramblock_addr +
+                vfn * TARGET_PAGE_SIZE), TARGET_PAGE_SIZE);
+
+    return crc;
+}
+
+static bool save_ramblock_hash(struct RamblockDirtyInfo *info)
+{
+    unsigned int sample_pages_count;
+    int i;
+    GRand *rand;
+
+    sample_pages_count = info->sample_pages_count;
+
+    /* ramblock size less than one page, return success to skip this ramblock */
+    if (unlikely(info->ramblock_pages == 0 || sample_pages_count == 0)) {
+        return true;
+    }
+
+    info->hash_result = g_try_malloc0_n(sample_pages_count,
+                                        sizeof(uint32_t));
+    if (!info->hash_result) {
+        return false;
+    }
+
+    info->sample_page_vfn = g_try_malloc0_n(sample_pages_count,
+                                            sizeof(uint64_t));
+    if (!info->sample_page_vfn) {
+        g_free(info->hash_result);
+        return false;
+    }
+
+    rand  = g_rand_new();
+    for (i = 0; i < sample_pages_count; i++) {
+        info->sample_page_vfn[i] = g_rand_int_range(rand, 0,
+                                                    info->ramblock_pages - 1);
+        info->hash_result[i] = get_ramblock_vfn_hash(info,
+                                                     info->sample_page_vfn[i]);
+    }
+    g_rand_free(rand);
+
+    return true;
+}
+
+static void get_ramblock_dirty_info(RAMBlock *block,
+                                    struct RamblockDirtyInfo *info,
+                                    struct DirtyRateConfig *config)
+{
+    uint64_t sample_pages_per_gigabytes = config->sample_pages_per_gigabytes;
+
+    /* Right shift 30 bits to calc ramblock size in GB */
+    info->sample_pages_count = (qemu_ram_get_used_length(block) *
+                                sample_pages_per_gigabytes) >> 30;
+    /* Right shift TARGET_PAGE_BITS to calc page count */
+    info->ramblock_pages = qemu_ram_get_used_length(block) >>
+                           TARGET_PAGE_BITS;
+    info->ramblock_addr = qemu_ram_get_host_addr(block);
+    strcpy(info->idstr, qemu_ram_get_idstr(block));
+}
+
+static bool record_ramblock_hash_info(struct RamblockDirtyInfo **block_dinfo,
+                                      struct DirtyRateConfig config,
+                                      int *block_count)
+{
+    struct RamblockDirtyInfo *info = NULL;
+    struct RamblockDirtyInfo *dinfo = NULL;
+    RAMBlock *block = NULL;
+    int total_count = 0;
+    int index = 0;
+    bool ret = false;
+
+    RAMBLOCK_FOREACH_MIGRATABLE(block) {
+        total_count++;
+    }
+
+    dinfo = g_try_malloc0_n(total_count, sizeof(struct RamblockDirtyInfo));
+    if (dinfo == NULL) {
+        goto out;
+    }
+
+    RAMBLOCK_FOREACH_MIGRATABLE(block) {
+        if (index >= total_count) {
+            break;
+        }
+        info = &dinfo[index];
+        get_ramblock_dirty_info(block, info, &config);
+        if (!save_ramblock_hash(info)) {
+            goto out;
+        }
+        index++;
+    }
+    ret = true;
+
+out:
+    *block_count = index;
+    *block_dinfo = dinfo;
+    return ret;
+}
+
 static void calculate_dirtyrate(struct DirtyRateConfig config)
 {
     /* todo */
-- 
2.26.2