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From a00bde30c0730d3434d9f4556a9cb119f3f8d68d Mon Sep 17 00:00:00 2001
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From: Dr. David Alan Gilbert (git) <dgilbert@redhat.com>
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Date: Thu, 8 May 2014 10:58:42 +0200
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Subject: [PATCH 20/30] XBZRLE: Fix one XBZRLE corruption issues
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RH-Author: Dr. David Alan Gilbert (git) <dgilbert@redhat.com>
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Message-id: <1399546722-6350-5-git-send-email-dgilbert@redhat.com>
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Patchwork-id: 58744
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O-Subject: [RHEL7.1/RHEL7.0.z qemu-kvm PATCH 4/4] XBZRLE: Fix one XBZRLE corruption issues
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Bugzilla: 1110191
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RH-Acked-by: Juan Quintela <quintela@redhat.com>
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RH-Acked-by: Markus Armbruster <armbru@redhat.com>
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RH-Acked-by: Amit Shah <amit.shah@redhat.com>
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From: ChenLiang <chenliang88@huawei.com>
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The page may not be inserted into cache after executing save_xbzrle_page.
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In case of failure to insert, the original page should be sent rather
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than the page in the cache.
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Signed-off-by: ChenLiang <chenliang88@huawei.com>
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Signed-off-by: Gonglei <arei.gonglei@huawei.com>
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Reviewed-by: Juan Quintela <quintela@redhat.com>
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Signed-off-by: Juan Quintela <quintela@redhat.com>
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(cherry picked from commit 1534ee93cc6be992c05577886b24bd44c37ecff6)
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---
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 arch_init.c | 25 +++++++++++++------------
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 1 file changed, 13 insertions(+), 12 deletions(-)
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Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
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---
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 arch_init.c |   25 +++++++++++++------------
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 1 files changed, 13 insertions(+), 12 deletions(-)
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diff --git a/arch_init.c b/arch_init.c
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index 80e48f2..22f7def 100644
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--- a/arch_init.c
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+++ b/arch_init.c
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@@ -341,7 +341,7 @@ static void xbzrle_cache_zero_page(ram_addr_t current_addr)
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 #define ENCODING_FLAG_XBZRLE 0x1
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-static int save_xbzrle_page(QEMUFile *f, uint8_t *current_data,
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+static int save_xbzrle_page(QEMUFile *f, uint8_t **current_data,
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                             ram_addr_t current_addr, RAMBlock *block,
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                             ram_addr_t offset, int cont, bool last_stage)
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 {
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@@ -349,19 +349,23 @@ static int save_xbzrle_page(QEMUFile *f, uint8_t *current_data,
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     uint8_t *prev_cached_page;
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     if (!cache_is_cached(XBZRLE.cache, current_addr)) {
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+        acct_info.xbzrle_cache_miss++;
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         if (!last_stage) {
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-            if (cache_insert(XBZRLE.cache, current_addr, current_data) == -1) {
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+            if (cache_insert(XBZRLE.cache, current_addr, *current_data) == -1) {
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                 return -1;
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+            } else {
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+                /* update *current_data when the page has been
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+                   inserted into cache */
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+                *current_data = get_cached_data(XBZRLE.cache, current_addr);
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             }
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         }
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-        acct_info.xbzrle_cache_miss++;
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         return -1;
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     }
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     prev_cached_page = get_cached_data(XBZRLE.cache, current_addr);
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     /* save current buffer into memory */
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-    memcpy(XBZRLE.current_buf, current_data, TARGET_PAGE_SIZE);
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+    memcpy(XBZRLE.current_buf, *current_data, TARGET_PAGE_SIZE);
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     /* XBZRLE encoding (if there is no overflow) */
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     encoded_len = xbzrle_encode_buffer(prev_cached_page, XBZRLE.current_buf,
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@@ -374,7 +378,10 @@ static int save_xbzrle_page(QEMUFile *f, uint8_t *current_data,
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         DPRINTF("Overflow\n");
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         acct_info.xbzrle_overflows++;
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         /* update data in the cache */
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-        memcpy(prev_cached_page, current_data, TARGET_PAGE_SIZE);
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+        if (!last_stage) {
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+            memcpy(prev_cached_page, *current_data, TARGET_PAGE_SIZE);
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+            *current_data = prev_cached_page;
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+        }
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         return -1;
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     }
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@@ -599,15 +606,9 @@ static int ram_save_block(QEMUFile *f, bool last_stage)
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                  */
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                 xbzrle_cache_zero_page(current_addr);
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             } else if (!ram_bulk_stage && migrate_use_xbzrle()) {
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-                bytes_sent = save_xbzrle_page(f, p, current_addr, block,
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+                bytes_sent = save_xbzrle_page(f, &p, current_addr, block,
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                                               offset, cont, last_stage);
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                 if (!last_stage) {
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-                    /* We must send exactly what's in the xbzrle cache
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-                     * even if the page wasn't xbzrle compressed, so that
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-                     * it's right next time.
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-                     */
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-                    p = get_cached_data(XBZRLE.cache, current_addr);
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-
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                     /* Can't send this cached data async, since the cache page
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                      * might get updated before it gets to the wire
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                      */
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-- 
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1.7.1
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