[Xen-changelog] [xen staging] x86/HVM: avoid memory_type_changed() invocations when possible

[patchbot@xxxxxxx]

commit 4e34e0586f77aafd1cb85142de9c5e7ceaff84ee
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Wed Jul 18 10:36:40 2018 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Jul 18 10:36:40 2018 +0200

    x86/HVM: avoid memory_type_changed() invocations when possible
    
    They're expensive, and nothing changes if MTRRs are disabled and any of
    the ranges gets changed, or if fixed range MTRRs are disabled and any of
    them gets changed.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Acked-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
---
 xen/arch/x86/hvm/mtrr.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/hvm/mtrr.c b/xen/arch/x86/hvm/mtrr.c
index eb86cbacb4..c502dda693 100644
--- a/xen/arch/x86/hvm/mtrr.c
+++ b/xen/arch/x86/hvm/mtrr.c
@@ -472,7 +472,9 @@ bool_t mtrr_fix_range_msr_set(struct domain *d, struct 
mtrr_state *m,
                 return 0;
 
         fixed_range_base[row] = msr_content;
-        memory_type_changed(d);
+
+        if ( m->enabled && m->fixed_enabled )
+            memory_type_changed(d);
     }
 
     return 1;
@@ -515,7 +517,8 @@ bool_t mtrr_var_range_msr_set(
 
     m->overlapped = is_var_mtrr_overlapped(m);
 
-    memory_type_changed(d);
+    if ( m->enabled )
+        memory_type_changed(d);
 
     return 1;
 }
--
generated by git-patchbot for /home/xen/git/xen.git#staging

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