[Xen-devel] [PATCH] x86/IO-APIC: fix build with gcc9

["Jan Beulich" <JBeulich@xxxxxxxx>]

There are a number of pointless __packed attributes which cause gcc 9 to
legitimately warn:

utils.c: In function 'vtd_dump_iommu_info':
utils.c:287:33: error: converting a packed 'struct IO_APIC_route_entry' pointer 
(alignment 1) to a 'struct IO_APIC_route_remap_entry' pointer (alignment 8) may 
result in an unaligned pointer value [-Werror=address-of-packed-member]
  287 |                 remap = (struct IO_APIC_route_remap_entry *) &rte;
      |                                 ^~~~~~~~~~~~~~~~~~~~~~~~~

intremap.c: In function 'ioapic_rte_to_remap_entry':
intremap.c:343:25: error: converting a packed 'struct IO_APIC_route_entry' 
pointer (alignment 1) to a 'struct IO_APIC_route_remap_entry' pointer 
(alignment 8) may result in an unaligned pointer value 
[-Werror=address-of-packed-member]
  343 |     remap_rte = (struct IO_APIC_route_remap_entry *) old_rte;
      |                         ^~~~~~~~~~~~~~~~~~~~~~~~~

Simply drop these attributes. Take the liberty and also re-format the
structure definitions at the same time.

Reported-by: Charles Arnold <carnold@xxxxxxxx>
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/include/asm-x86/io_apic.h
+++ b/xen/include/asm-x86/io_apic.h
@@ -33,42 +33,42 @@
  * The structure of the IO-APIC:
  */
 union IO_APIC_reg_00 {
-       u32     raw;
-       struct __packed {
-               u32     __reserved_2    : 14,
-                       LTS             :  1,
-                       delivery_type   :  1,
-                       __reserved_1    :  8,
-                       ID              :  8;
-       } bits;
+    uint32_t raw;
+    struct {
+        unsigned int __reserved_2:14;
+        unsigned int LTS:1;
+        unsigned int delivery_type:1;
+        unsigned int __reserved_1:8;
+        unsigned int ID:8;
+    } bits;
 };
 
 union IO_APIC_reg_01 {
-       u32     raw;
-       struct __packed {
-               u32     version         :  8,
-                       __reserved_2    :  7,
-                       PRQ             :  1,
-                       entries         :  8,
-                       __reserved_1    :  8;
-       } bits;
+    uint32_t raw;
+    struct {
+        unsigned int version:8;
+        unsigned int __reserved_2:7;
+        unsigned int PRQ:1;
+        unsigned int entries:8;
+        unsigned int __reserved_1:8;
+    } bits;
 };
 
 union IO_APIC_reg_02 {
-       u32     raw;
-       struct __packed {
-               u32     __reserved_2    : 24,
-                       arbitration     :  4,
-                       __reserved_1    :  4;
-       } bits;
+    uint32_t raw;
+    struct {
+        unsigned int __reserved_2:24;
+        unsigned int arbitration:4;
+        unsigned int __reserved_1:4;
+    } bits;
 };
 
 union IO_APIC_reg_03 {
-       u32     raw;
-       struct __packed {
-               u32     boot_DT         :  1,
-                       __reserved_1    : 31;
-       } bits;
+    uint32_t raw;
+    struct {
+        unsigned int boot_DT:1;
+        unsigned int __reserved_1:31;
+    } bits;
 };
 
 /*
@@ -88,35 +88,36 @@ enum ioapic_irq_destination_types {
        dest_ExtINT = 7
 };
 
-struct __packed IO_APIC_route_entry {
-       __u32   vector          :  8,
-               delivery_mode   :  3,   /* 000: FIXED
-                                        * 001: lowest prio
-                                        * 111: ExtINT
-                                        */
-               dest_mode       :  1,   /* 0: physical, 1: logical */
-               delivery_status :  1,
-               polarity        :  1,
-               irr             :  1,
-               trigger         :  1,   /* 0: edge, 1: level */
-               mask            :  1,   /* 0: enabled, 1: disabled */
-               __reserved_2    : 15;
-
-       union {         struct { __u32
-                                       __reserved_1    : 24,
-                                       physical_dest   :  4,
-                                       __reserved_2    :  4;
-                       } physical;
-
-                       struct { __u32
-                                       __reserved_1    : 24,
-                                       logical_dest    :  8;
-                       } logical;
-
-                       /* used when Interrupt Remapping with EIM is enabled */
-                       __u32 dest32;
-       } dest;
-
+struct IO_APIC_route_entry {
+    unsigned int vector:8;
+    unsigned int delivery_mode:3; /*
+                                   * 000: FIXED
+                                   * 001: lowest prio
+                                   * 111: ExtINT
+                                   */
+    unsigned int dest_mode:1;     /* 0: physical, 1: logical */
+    unsigned int delivery_status:1;
+    unsigned int polarity:1;      /* 0: low, 1: high */
+    unsigned int irr:1;
+    unsigned int trigger:1;       /* 0: edge, 1: level */
+    unsigned int mask:1;          /* 0: enabled, 1: disabled */
+    unsigned int __reserved_2:15;
+
+    union {
+        struct {
+            unsigned int __reserved_1:24;
+            unsigned int physical_dest:4;
+            unsigned int __reserved_2:4;
+        } physical;
+
+        struct {
+            unsigned int __reserved_1:24;
+            unsigned int logical_dest:8;
+        } logical;
+
+        /* used when Interrupt Remapping with EIM is enabled */
+        unsigned int dest32;
+    } dest;
 };
 
 /*




_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel