[v3,07/22] x86/xstate: avoid accounting for unsupported components

Commit Message

Jan Beulich April 22, 2021, 2:47 p.m. UTC

There's no point in including unsupported components in the size
calculations of xstate_{alloc,update}_save_area().

Signed-off-by: Jan Beulich <[e-mail]>

Patch

--- a/xen/arch/x86/xstate.c
+++ b/xen/arch/x86/xstate.c
@@ -501,8 +501,12 @@  int xstate_alloc_save_area(struct vcpu *
         unsigned int i;
 
         for ( size = 0, i = 2; i < xstate_features; ++i )
+        {
+            if ( !(xfeature_mask & (1ul << i)) )
+                continue;
             if ( size < xstate_size(i) )
                 size = xstate_size(i);
+        }
         size += XSTATE_AREA_MIN_SIZE;
     }
 
@@ -543,6 +547,8 @@  int xstate_update_save_area(struct vcpu
 
     for ( size = old = XSTATE_AREA_MIN_SIZE, i = 2; i < xstate_features; ++i )
     {
+        if ( !(xfeature_mask & (1ul << i)) )
+            continue;
         if ( xcr0_max & (1ul << i) )
             size = max(size, xstate_offset(i) + xstate_size(i));
         if ( v->arch.xcr0_accum & (1ul << i) )