[Qemu-devel] [PATCH 2/2] memory: fix the eventfd data endianness according to the host

[Greg Kurz]

The data argument is a host entity. It is not related to the target
endianness. Let's introduce a HOST_WORDS_BIGENDIAN based helper for
that.

This patch fixes ioeventfd and vhost for a ppc64le host running a ppc64le
guest (only virtqueue 0 was handled, all others being byteswapped because
of TARGET_WORDS_BIGENDIAN). It doesn't change functionnality for fixed
endian architectures (i.e. doesn't break x86).

Reported-by: Cédric Le Goater <c...@fr.ibm.com>
Signed-off-by: Greg Kurz <gk...@linux.vnet.ibm.com>
---
 memory.c |   13 +++++++++++--
 1 file changed, 11 insertions(+), 2 deletions(-)

diff --git a/memory.c b/memory.c
index 6291cc0..1e29d40 100644
--- a/memory.c
+++ b/memory.c
@@ -1549,6 +1549,15 @@ void memory_region_clear_flush_coalesced(MemoryRegion 
*mr)
     }
 }
 
+static bool eventfd_wrong_endianness(MemoryRegion *mr)
+{
+#ifdef HOST_WORDS_BIGENDIAN
+    return mr->ops->endianness == DEVICE_LITTLE_ENDIAN;
+#else
+    return mr->ops->endianness == DEVICE_BIG_ENDIAN;
+#endif
+}
+
 void memory_region_add_eventfd(MemoryRegion *mr,
                                hwaddr addr,
                                unsigned size,
@@ -1565,7 +1574,7 @@ void memory_region_add_eventfd(MemoryRegion *mr,
     };
     unsigned i;
 
-    adjust_endianness(&mrfd.data, size, memory_region_wrong_endianness(mr));
+    adjust_endianness(&mrfd.data, size, eventfd_wrong_endianness(mr));
     memory_region_transaction_begin();
     for (i = 0; i < mr->ioeventfd_nb; ++i) {
         if (memory_region_ioeventfd_before(mrfd, mr->ioeventfds[i])) {
@@ -1598,7 +1607,7 @@ void memory_region_del_eventfd(MemoryRegion *mr,
     };
     unsigned i;
 
-    adjust_endianness(&mrfd.data, size, memory_region_wrong_endianness(mr));
+    adjust_endianness(&mrfd.data, size, eventfd_wrong_endianness(mr));
     memory_region_transaction_begin();
     for (i = 0; i < mr->ioeventfd_nb; ++i) {
         if (memory_region_ioeventfd_equal(mrfd, mr->ioeventfds[i])) {