[Xen-changelog] [xen master] x86: use CLFLUSHOPT when available

[patchbot@xxxxxxx]

commit 623c720fc8da3f8fd4b4afc7a9ba3d3de53e1767
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Thu Feb 11 16:46:11 2016 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Thu Feb 11 16:46:11 2016 +0100

    x86: use CLFLUSHOPT when available
    
    Also drop an unnecessary va adjustment in the code being touched.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/arch/x86/flushtlb.c          | 8 +++++---
 xen/include/asm-x86/cpufeature.h | 1 +
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/xen/arch/x86/flushtlb.c b/xen/arch/x86/flushtlb.c
index 5d5d79c..90a004f 100644
--- a/xen/arch/x86/flushtlb.c
+++ b/xen/arch/x86/flushtlb.c
@@ -139,10 +139,12 @@ void flush_area_local(const void *va, unsigned int flags)
              c->x86_clflush_size && c->x86_cache_size && sz &&
              ((sz >> 10) < c->x86_cache_size) )
         {
-            va = (const void *)((unsigned long)va & ~(sz - 1));
+            alternative(ASM_NOP3, "sfence", X86_FEATURE_CLFLUSHOPT);
             for ( i = 0; i < sz; i += c->x86_clflush_size )
-                 asm volatile ( "clflush %0"
-                                : : "m" (((const char *)va)[i]) );
+                 alternative_input("rex clflush %0",
+                                   "data16 clflush %0",
+                                   X86_FEATURE_CLFLUSHOPT,
+                                   "m" (((const char *)va)[i]));
         }
         else
         {
diff --git a/xen/include/asm-x86/cpufeature.h b/xen/include/asm-x86/cpufeature.h
index e7e369b..442f0a8 100644
--- a/xen/include/asm-x86/cpufeature.h
+++ b/xen/include/asm-x86/cpufeature.h
@@ -152,6 +152,7 @@
 #define X86_FEATURE_ADX                (7*32+19) /* ADCX, ADOX instructions */
 #define X86_FEATURE_SMAP       (7*32+20) /* Supervisor Mode Access Prevention 
*/
 #define X86_FEATURE_PCOMMIT    (7*32+22) /* PCOMMIT instruction */
+#define X86_FEATURE_CLFLUSHOPT (7*32+23) /* CLFLUSHOPT instruction */
 
 /* Intel-defined CPU features, CPUID level 0x00000007:0 (ecx), word 8 */
 #define X86_FEATURE_PKU        (8*32+ 3) /* Protection Keys for Userspace */
--
generated by git-patchbot for /home/xen/git/xen.git#master

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