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[Xen-devel] [PATCH] x86/vmx: fix build with clang 3.8.0

The usage of the __transparent__ attribute in 991033fa introduces some issues
when compiled with clang 3.8.0:

xen/include/asm/hvm/vmx/vmx.h:605:15: error: transparent_union attribute can 
only be
      applied to a union definition; attribute ignored 
typedef union __transparent__ ept_qual {
xen/include/xen/compiler.h:50:44: note: expanded from macro '__transparent__'
#define __transparent__     __attribute__((__transparent_union__))

This can be easily fixed by moving the attribute to the end of the definition,
but then the following error triggers:

xen/include/asm/hvm/vmx/vmx.h:607:5: error: size of field '' (16 bits) does not
      match the size of the first field in transparent union; transparent_union 
attribute ignored
    struct {
xen/include/asm/hvm/vmx/vmx.h:606:19: note: size of first field is 64 bits
    unsigned long raw;

Which can be fixed by introducing a new field in the nested structure that
contains the padding in order to match the size of an unsigned long.

Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Cc: Jun Nakajima <jun.nakajima@xxxxxxxxx>
Cc: Kevin Tian <kevin.tian@xxxxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
 xen/include/asm-x86/hvm/vmx/vmx.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/xen/include/asm-x86/hvm/vmx/vmx.h 
index 5f7512b..52646b7 100644
--- a/xen/include/asm-x86/hvm/vmx/vmx.h
+++ b/xen/include/asm-x86/hvm/vmx/vmx.h
@@ -602,15 +602,16 @@ void vmx_pi_hooks_assign(struct domain *d);
 void vmx_pi_hooks_deassign(struct domain *d);
 /* EPT violation qualifications definitions */
-typedef union __transparent__ ept_qual {
+typedef union ept_qual {
     unsigned long raw;
     struct {
         bool read:1, write:1, fetch:1,
             eff_read:1, eff_write:1, eff_exec:1, /* eff_user_exec */:1,
             gla_fault:1; /* Valid iff gla_valid. */
+        unsigned long /* pad */:55;
-} ept_qual_t;
+} ept_qual_t __transparent__;
 #define EPT_L4_PAGETABLE_SHIFT      39
 #define EPT_PAGETABLE_ENTRIES       512
2.10.1 (Apple Git-78)

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