[qemu-xen stable-4.18] dump: kdump-zlib data pages not dumped with pvtime/aarch64

[patchbot@xxxxxxx]

commit a11a2007a50d6d2b8e57605fc2ec40b9f962df13
Author:     Dongli Zhang <dongli.zhang@xxxxxxxxxx>
AuthorDate: Wed Jul 12 22:58:19 2023 -0700
Commit:     Michael Tokarev <mjt@xxxxxxxxxx>
CommitDate: Sun Sep 10 19:39:41 2023 +0300

    dump: kdump-zlib data pages not dumped with pvtime/aarch64
    
    The kdump-zlib data pages are not dumped from aarch64 host when the
    'pvtime' is involved, that is, when the block->target_end is not aligned to
    page_size. In the below example, it is expected to dump two blocks.
    
    (qemu) info mtree -f
    ... ...
      00000000090a0000-00000000090a0fff (prio 0, ram): pvtime KVM
    ... ...
      0000000040000000-00000001bfffffff (prio 0, ram): mach-virt.ram KVM
    ... ...
    
    However, there is an issue with get_next_page() so that the pages for
    "mach-virt.ram" will not be dumped.
    
    At line 1296, although we have reached at the end of the 'pvtime' block,
    since it is not aligned to the page_size (e.g., 0x10000), it will not break
    at line 1298.
    
    1255 static bool get_next_page(GuestPhysBlock **blockptr, uint64_t *pfnptr,
    1256                           uint8_t **bufptr, DumpState *s)
    ... ...
    1294             memcpy(buf + addr % page_size, hbuf, n);
    1295             addr += n;
    1296             if (addr % page_size == 0) {
    1297                 /* we filled up the page */
    1298                 break;
    1299             }
    
    As a result, get_next_page() will continue to the next
    block ("mach-virt.ram"). Finally, when get_next_page() returns to the
    caller:
    
    - 'pfnptr' is referring to the 'pvtime'
    - but 'blockptr' is referring to the "mach-virt.ram"
    
    When get_next_page() is called the next time, "*pfnptr += 1" still refers
    to the prior 'pvtime'. It will exit immediately because it is out of the
    range of the current "mach-virt.ram".
    
    The fix is to break when it is time to come to the next block, so that both
    'pfnptr' and 'blockptr' refer to the same block.
    
    Fixes: 94d788408d2d ("dump: fix kdump to work over non-aligned blocks")
    Cc: Joe Jin <joe.jin@xxxxxxxxxx>
    Signed-off-by: Dongli Zhang <dongli.zhang@xxxxxxxxxx>
    Reviewed-by: Marc-André Lureau <marcandre.lureau@xxxxxxxxxx>
    Message-ID: <20230713055819.30497-1-dongli.zhang@xxxxxxxxxx>
    (cherry picked from commit 8a64609eea8cb2bac015968c4b62da5bce266e22)
    Signed-off-by: Michael Tokarev <mjt@xxxxxxxxxx>
---
 dump/dump.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/dump/dump.c b/dump/dump.c
index 1f1a6edcab..d4ef713cd0 100644
--- a/dump/dump.c
+++ b/dump/dump.c
@@ -1293,8 +1293,8 @@ static bool get_next_page(GuestPhysBlock **blockptr, 
uint64_t *pfnptr,
 
             memcpy(buf + addr % page_size, hbuf, n);
             addr += n;
-            if (addr % page_size == 0) {
-                /* we filled up the page */
+            if (addr % page_size == 0 || addr >= block->target_end) {
+                /* we filled up the page or the current block is finished */
                 break;
             }
         } else {
--
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