x86: reduce magic number usage in XSAVE code

Signed-off-by: Wei Gang <gang.wei@intel.com>

xen/arch/x86/hvm/hvm.c

@@ -2223,7 +2223,7 @@ void hvm_cpuid(unsigned int input, unsigned int *eax, unsigned int *ebx,
         if ( count == 0 && v->arch.xcr0 ) 
         {
             /* reset EBX to default value first */
-            *ebx = 576; 
+            *ebx = XSAVE_AREA_MIN_SIZE; 
             for ( sub_leaf = 2; sub_leaf < 64; sub_leaf++ )
             {
                 if ( !(v->arch.xcr0 & (1ULL << sub_leaf)) )

xen/arch/x86/i387.c

@@ -221,7 +221,6 @@ static void restore_fpu(struct vcpu *v)
 }
 
 #define XSTATE_CPUID 0xd
-#define XSAVE_AREA_MIN_SIZE (512 + 64) /* FP/SSE + XSAVE.HEADER */
 
 /*
  * Maximum size (in byte) of the XSAVE/XRSTOR save area required by all

xen/include/asm-x86/i387.h

@@ -21,13 +21,14 @@ void xsave_init(void);
 int xsave_alloc_save_area(struct vcpu *v);
 void xsave_free_save_area(struct vcpu *v);
 
+#define XSAVE_AREA_MIN_SIZE (512 + 64) /* FP/SSE + XSAVE.HEADER */
 #define XSTATE_FP       (1ULL << 0)
 #define XSTATE_SSE      (1ULL << 1)
 #define XSTATE_YMM      (1ULL << 2)
 #define XSTATE_LWP      (1ULL << 62) /* AMD lightweight profiling */
 #define XSTATE_FP_SSE   (XSTATE_FP | XSTATE_SSE)
 #define XCNTXT_MASK     (XSTATE_FP | XSTATE_SSE | XSTATE_YMM | XSTATE_LWP)
-#define XSTATE_YMM_OFFSET  (512 + 64)
+#define XSTATE_YMM_OFFSET  XSAVE_AREA_MIN_SIZE
 #define XSTATE_YMM_SIZE    256
 #define XSAVEOPT        (1 << 0)