From: Paolo Bonzini <pbonzini@redhat.com>
Date: Mon, 29 Jul 2013 12:27:39 +0000 (+0200)
Subject: exec: fix writing to MMIO area with non-power-of-two length
X-Git-Tag: qemu-xen-4.4.0-rc1~1^2~33
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=9fab8e1fe15014a4bd147eeedd2491bcfbba4e59;p=qemu-upstream-4.4-testing.git

exec: fix writing to MMIO area with non-power-of-two length

The problem is introduced by commit 2332616 (exec: Support 64-bit
operations in address_space_rw, 2013-07-08).  Before that commit,
memory_access_size would only return 1/2/4.

Since alignment is already handled above, reduce l to the largest
power of two that is smaller than l.

Cc: qemu-stable@nongnu.org
Reported-by: Oleksii Shevchuk <alxchk@gmail.com>
Tested-by: Oleksii Shevchuk <alxchk@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit 098178f2749a63fbbb1a626dcc7d939d5cb2bde7)

Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>
---

diff --git a/exec.c b/exec.c
index 3ca938121..394f7e2b1 100644
--- a/exec.c
+++ b/exec.c
@@ -1928,6 +1928,9 @@ static int memory_access_size(MemoryRegion *mr, unsigned l, hwaddr addr)
     if (l > access_size_max) {
         l = access_size_max;
     }
+    if (l & (l - 1)) {
+        l = 1 << (qemu_fls(l) - 1);
+    }
 
     return l;
 }