[PATCH v2 15/23] x86/pv: Deduplicate is_canonical_address() in do_set_segment_base()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

This is really a rearrangement to make adding FRED support easier.

No functional change.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>

v2:
 * New

There is a marginal code size improvement:

  add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-46 (-46)
  Function                                     old     new   delta
  do_set_segment_base                          496     450     -46

but it does get undone by the FRED support.
---
 xen/arch/x86/pv/misc-hypercalls.c | 32 ++++++++++++++++---------------
 1 file changed, 17 insertions(+), 15 deletions(-)

diff --git a/xen/arch/x86/pv/misc-hypercalls.c 
b/xen/arch/x86/pv/misc-hypercalls.c
index 7a37f16bf038..4c2abeb4add8 100644
--- a/xen/arch/x86/pv/misc-hypercalls.c
+++ b/xen/arch/x86/pv/misc-hypercalls.c
@@ -176,27 +176,29 @@ long do_set_segment_base(unsigned int which, unsigned 
long base)
     switch ( which )
     {
     case SEGBASE_FS:
-        if ( is_canonical_address(base) )
-            write_fs_base(base);
-        else
+    case SEGBASE_GS_USER:
+    case SEGBASE_GS_KERNEL:
+        if ( !is_canonical_address(base) )
+        {
             ret = -EINVAL;
-        break;
+            break;
+        }
 
-    case SEGBASE_GS_USER:
-        if ( is_canonical_address(base) )
+        switch ( which )
         {
-            write_gs_shadow(base);
+        case SEGBASE_FS:
+            write_fs_base(base);
+            break;
+
+        case SEGBASE_GS_USER:
             v->arch.pv.gs_base_user = base;
-        }
-        else
-            ret = -EINVAL;
-        break;
+            write_gs_shadow(base);
+            break;
 
-    case SEGBASE_GS_KERNEL:
-        if ( is_canonical_address(base) )
+        case SEGBASE_GS_KERNEL:
             write_gs_base(base);
-        else
-            ret = -EINVAL;
+            break;
+        }
         break;
 
     case SEGBASE_GS_USER_SEL:
-- 
2.39.5