[Xen-changelog] [xen master] xen/x86: Drop sync_core()

[patchbot@xxxxxxx]

commit 7c96d4e6b1452af3c8a11a09cab9c7f488b73733
Author:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
AuthorDate: Fri May 19 11:01:42 2017 +0100
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Wed May 31 17:54:19 2017 +0100

    xen/x86: Drop sync_core()
    
    As identified in Linux c/s c198b121b1a1d "x86/asm: Rewrite sync_core() to 
use
    IRET-to-self", sync_core() is only appropriate for two very specific 
usecases.
    
    Xen doesn't have need of either of these usecases, so drop sync_core() to
    avoid any misuse.
    
    In the unlikely event that we do gain a legitimate use for sync_core(), it
    should be reintroduced as a mov to %cr2 rather than cpuid, which has a lower
    overhead.
    
    Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
    Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/include/asm-x86/processor.h | 11 -----------
 1 file changed, 11 deletions(-)

diff --git a/xen/include/asm-x86/processor.h b/xen/include/asm-x86/processor.h
index 1d1a4ff..6a335d3 100644
--- a/xen/include/asm-x86/processor.h
+++ b/xen/include/asm-x86/processor.h
@@ -396,17 +396,6 @@ static inline bool_t read_pkru_wd(uint32_t pkru, unsigned 
int pkey)
     outb((data), 0x23); \
 } while (0)
 
-/* Stop speculative execution */
-static inline void sync_core(void)
-{
-    int tmp;
-    asm volatile (
-        "cpuid"
-        : "=a" (tmp)
-        : "0" (1)
-        : "ebx","ecx","edx","memory" );
-}
-
 static always_inline void __monitor(const void *eax, unsigned long ecx,
                                     unsigned long edx)
 {
--
generated by git-patchbot for /home/xen/git/xen.git#master

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