[xen master] x86/mm: re-arrange type check around _get_page_type()'s TLB flush

[patchbot@xxxxxxx]

commit 8eb15275cd5d945acbc0f70a358255dea94117cf
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Mon Aug 15 08:53:11 2022 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Mon Aug 15 08:53:11 2022 +0200

    x86/mm: re-arrange type check around _get_page_type()'s TLB flush
    
    Checks dependent on only d and x can be pulled out, thus allowing to
    skip the flush mask calculation.
    
    (Also-)Suggested-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/arch/x86/mm.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 40e132b9ba..db1817b691 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -3020,7 +3020,10 @@ static int _get_page_type(struct page_info *page, 
unsigned long type,
         if ( d && shadow_mode_enabled(d) )
             shadow_prepare_page_type_change(d, page);
 
-        if ( (x & PGT_type_mask) != type )
+        if ( (x & PGT_type_mask) != type &&
+             /* Shadow mode: track only writable pages. */
+             (!shadow_mode_enabled(d) ||
+              ((x & PGT_type_mask) == PGT_writable_page)) )
         {
             /*
              * On type change we check to flush stale TLB entries. It is
@@ -3035,10 +3038,7 @@ static int _get_page_type(struct page_info *page, 
unsigned long type,
             /* Don't flush if the timestamp is old enough */
             tlbflush_filter(mask, page->tlbflush_timestamp);
 
-            if ( unlikely(!cpumask_empty(mask)) &&
-                 /* Shadow mode: track only writable pages. */
-                 (!shadow_mode_enabled(d) ||
-                  ((x & PGT_type_mask) == PGT_writable_page)) )
+            if ( unlikely(!cpumask_empty(mask)) )
             {
                 perfc_incr(need_flush_tlb_flush);
                 /*
--
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