This completes the 512 byte structure, allowing the union to
be removed.  Assert that the structure layout is as expected.

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/i386/cpu.h | 39 +++++++++++++++++++++++++--------------
 1 file changed, 25 insertions(+), 14 deletions(-)

diff --git a/target/i386/cpu.h b/target/i386/cpu.h
index 91170a088a..fdd318963a 100644
--- a/target/i386/cpu.h
+++ b/target/i386/cpu.h
@@ -1425,23 +1425,34 @@ typedef struct {
  */
 #define UNASSIGNED_APIC_ID 0xFFFFFFFF
 
-typedef union X86LegacyXSaveArea {
-    struct {
-        uint16_t fcw;
-        uint16_t fsw;
-        uint8_t ftw;
-        uint8_t reserved;
-        uint16_t fpop;
-        uint64_t fpip;
-        uint64_t fpdp;
-        uint32_t mxcsr;
-        uint32_t mxcsr_mask;
-        FPReg fpregs[8];
-        uint8_t xmm_regs[16][16];
+typedef struct X86LegacyXSaveArea {
+    uint16_t fcw;
+    uint16_t fsw;
+    uint8_t ftw;
+    uint8_t reserved;
+    uint16_t fpop;
+    union {
+        struct {
+            uint64_t fpip;
+            uint64_t fpdp;
+        };
+        struct {
+            uint32_t fip;
+            uint32_t fcs;
+            uint32_t foo;
+            uint32_t fos;
+        };
     };
-    uint8_t data[512];
+    uint32_t mxcsr;
+    uint32_t mxcsr_mask;
+    FPReg fpregs[8];
+    uint8_t xmm_regs[16][16];
+    uint32_t hw_reserved[12];
+    uint32_t sw_reserved[12];
 } X86LegacyXSaveArea;
 
+QEMU_BUILD_BUG_ON(sizeof(X86LegacyXSaveArea) != 512);
+
 typedef struct X86XSaveHeader {
     uint64_t xstate_bv;
     uint64_t xcomp_bv;
-- 
2.34.1