[Stable-8.0.5 06/43] dump: kdump-zlib data pages not dumped with pvtime/aarch64

[Michael Tokarev]

From: Dongli Zhang <dongli.zhang@oracle.com>

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@oracle.com>
Signed-off-by: Dongli Zhang <dongli.zhang@oracle.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-ID: <20230713055819.30497-1-dongli.zhang@oracle.com>
(cherry picked from commit 8a64609eea8cb2bac015968c4b62da5bce266e22)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

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 {
-- 
2.39.2