hw/pci-bridge/cxl_upstream: Fix problem with g_steal_pointer()

When setting GLIB_VERSION_MAX_ALLOWED to GLIB_VERSION_2_58 or higher,
glib adds type safety checks to the g_steal_pointer() macro. This
triggers errors in the build_cdat_table() function which uses the
g_steal_pointer() for type-casting from one pointer type to the other
(which also looks quite weird since the local pointers have all been
declared with g_autofree though they are never freed here). Let's fix
it by using a proper typecast instead. For making this possible, we
have to remove the QEMU_PACKED attribute from some structs since GCC
otherwise complains that the source and destination pointer might
have different alignment restrictions. Removing the QEMU_PACKED should
be fine here since the structs are already naturally aligned. Anyway,
add some QEMU_BUILD_BUG_ON() statements to make sure that we've got
the right sizes (without padding in the structs).

Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

hw/pci-bridge/cxl_upstream.c

@@ -192,8 +192,8 @@ enum {
 
 static int build_cdat_table(CDATSubHeader ***cdat_table, void *priv)
 {
-    g_autofree CDATSslbis *sslbis_latency = NULL;
-    g_autofree CDATSslbis *sslbis_bandwidth = NULL;
+    CDATSslbis *sslbis_latency;
+    CDATSslbis *sslbis_bandwidth;
     CXLUpstreamPort *us = CXL_USP(priv);
     PCIBus *bus = &PCI_BRIDGE(us)->sec_bus;
     int devfn, sslbis_size, i;
@@ -270,8 +270,8 @@ static int build_cdat_table(CDATSubHeader ***cdat_table, void *priv)
     *cdat_table = g_new0(CDATSubHeader *, CXL_USP_CDAT_NUM_ENTRIES);
 
     /* Header always at start of structure */
-    (*cdat_table)[CXL_USP_CDAT_SSLBIS_LAT] = g_steal_pointer(&sslbis_latency);
-    (*cdat_table)[CXL_USP_CDAT_SSLBIS_BW] = g_steal_pointer(&sslbis_bandwidth);
+    (*cdat_table)[CXL_USP_CDAT_SSLBIS_LAT] = (CDATSubHeader *)sslbis_latency;
+    (*cdat_table)[CXL_USP_CDAT_SSLBIS_BW] = (CDATSubHeader *)sslbis_bandwidth;
 
     return CXL_USP_CDAT_NUM_ENTRIES;
 }

include/hw/cxl/cxl_cdat.h

@@ -130,7 +130,8 @@ typedef struct CDATSslbisHeader {
     uint8_t data_type;
     uint8_t reserved[3];
     uint64_t entry_base_unit;
-} QEMU_PACKED CDATSslbisHeader;
+} CDATSslbisHeader;
+QEMU_BUILD_BUG_ON(sizeof(CDATSslbisHeader) != 16);
 
 #define CDAT_PORT_ID_USP 0x100
 /* Switch Scoped Latency and Bandwidth Entry - CDAT Table 10 */
@@ -139,12 +140,13 @@ typedef struct CDATSslbe {
     uint16_t port_y_id;
     uint16_t latency_bandwidth;
     uint16_t reserved;
-} QEMU_PACKED CDATSslbe;
+} CDATSslbe;
+QEMU_BUILD_BUG_ON(sizeof(CDATSslbe) != 8);
 
 typedef struct CDATSslbis {
     CDATSslbisHeader sslbis_header;
     CDATSslbe sslbe[];
-} QEMU_PACKED CDATSslbis;
+} CDATSslbis;
 
 typedef struct CDATEntry {
     void *base;