From: Thomas Huth <thuth@redhat.com>

The first bitfield here is supposed to be used as a 64-bit equivalent
to the "uint64_t msi_addr" in the union. To make this work correctly
on big endian hosts, too, the __addr_hi field has to be part of the
bitfield, and the the bitfield members must be declared with "uint64_t"
instead of "uint32_t" - otherwise the values are placed in the wrong
bytes on big endian hosts.

Same applies to the 32-bit "msi_data" field: __resved1 must be part
of the bitfield, and the members must be declared with "uint32_t"
instead of "uint16_t".

Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20230802135723.178083-7-thuth@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
---
 include/hw/i386/x86-iommu.h | 50 +++++++++++++++++++------------------
 1 file changed, 26 insertions(+), 24 deletions(-)

diff --git a/include/hw/i386/x86-iommu.h b/include/hw/i386/x86-iommu.h
index 8d8d53b18b..bfd21649d0 100644
--- a/include/hw/i386/x86-iommu.h
+++ b/include/hw/i386/x86-iommu.h
@@ -87,40 +87,42 @@ struct X86IOMMU_MSIMessage {
     union {
         struct {
 #if HOST_BIG_ENDIAN
-            uint32_t __addr_head:12; /* 0xfee */
-            uint32_t dest:8;
-            uint32_t __reserved:8;
-            uint32_t redir_hint:1;
-            uint32_t dest_mode:1;
-            uint32_t __not_used:2;
+            uint64_t __addr_hi:32;
+            uint64_t __addr_head:12; /* 0xfee */
+            uint64_t dest:8;
+            uint64_t __reserved:8;
+            uint64_t redir_hint:1;
+            uint64_t dest_mode:1;
+            uint64_t __not_used:2;
 #else
-            uint32_t __not_used:2;
-            uint32_t dest_mode:1;
-            uint32_t redir_hint:1;
-            uint32_t __reserved:8;
-            uint32_t dest:8;
-            uint32_t __addr_head:12; /* 0xfee */
+            uint64_t __not_used:2;
+            uint64_t dest_mode:1;
+            uint64_t redir_hint:1;
+            uint64_t __reserved:8;
+            uint64_t dest:8;
+            uint64_t __addr_head:12; /* 0xfee */
+            uint64_t __addr_hi:32;
 #endif
-            uint32_t __addr_hi;
         } QEMU_PACKED;
         uint64_t msi_addr;
     };
     union {
         struct {
 #if HOST_BIG_ENDIAN
-            uint16_t trigger_mode:1;
-            uint16_t level:1;
-            uint16_t __resved:3;
-            uint16_t delivery_mode:3;
-            uint16_t vector:8;
+            uint32_t __resved1:16;
+            uint32_t trigger_mode:1;
+            uint32_t level:1;
+            uint32_t __resved:3;
+            uint32_t delivery_mode:3;
+            uint32_t vector:8;
 #else
-            uint16_t vector:8;
-            uint16_t delivery_mode:3;
-            uint16_t __resved:3;
-            uint16_t level:1;
-            uint16_t trigger_mode:1;
+            uint32_t vector:8;
+            uint32_t delivery_mode:3;
+            uint32_t __resved:3;
+            uint32_t level:1;
+            uint32_t trigger_mode:1;
+            uint32_t __resved1:16;
 #endif
-            uint16_t __resved1;
         } QEMU_PACKED;
         uint32_t msi_data;
     };
-- 
MST