[PULL 09/17] exec: Relax range check in ram_block_discard_range()

From: "Dr. David Alan Gilbert (git)" <dgilbert@redhat.com>
To: qemu-devel@nongnu.org, david@redhat.com, zhukeqian1@huawei.com,
	jiangkunkun@huawei.com, armbru@redhat.com,
	peter.maydell@linaro.org, huangy81@chinatelecom.cn
Cc: peterx@redhat.com
Subject: [PULL 09/17] exec: Relax range check in ram_block_discard_range()
Date: Tue, 11 May 2021 16:08:34 +0100	[thread overview]
Message-ID: <20210511150842.207155-10-dgilbert@redhat.com> (raw)
In-Reply-To: <20210511150842.207155-1-dgilbert@redhat.com>

From: David Hildenbrand <david@redhat.com>

We want to make use of ram_block_discard_range() in the RAM block resize
callback when growing a RAM block, *before* used_length is changed.
Let's relax the check. As RAM blocks always mmap the whole max_length area,
we cannot corrupt unrelated data.

Reviewed-by: Peter Xu <peterx@redhat.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Message-Id: <20210429112708.12291-6-david@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
---
 softmmu/physmem.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/softmmu/physmem.c b/softmmu/physmem.c
index 813a3efe8e..e1da81ed2f 100644
--- a/softmmu/physmem.c
+++ b/softmmu/physmem.c
@@ -3500,7 +3500,7 @@ int ram_block_discard_range(RAMBlock *rb, uint64_t start, size_t length)
         goto err;
     }
 
-    if ((start + length) <= rb->used_length) {
+    if ((start + length) <= rb->max_length) {
         bool need_madvise, need_fallocate;
         if (!QEMU_IS_ALIGNED(length, rb->page_size)) {
             error_report("ram_block_discard_range: Unaligned length: %zx",
@@ -3567,7 +3567,7 @@ int ram_block_discard_range(RAMBlock *rb, uint64_t start, size_t length)
     } else {
         error_report("ram_block_discard_range: Overrun block '%s' (%" PRIu64
                      "/%zx/" RAM_ADDR_FMT")",
-                     rb->idstr, start, length, rb->used_length);
+                     rb->idstr, start, length, rb->max_length);
     }
 
 err:
-- 
2.31.1


