[Xen-devel] [PATCH] x86: hide MWAITX from PV domains

["Jan Beulich" <JBeulich@xxxxxxxx>]

Since MWAIT is hidden too. (Linux starting with 4.3 is making use of
that feature, and is checking for it without looking at the MWAIT one.)

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -964,6 +964,7 @@ void pv_cpuid(struct cpu_user_regs *regs
         __clear_bit(X86_FEATURE_LWP % 32, &c);
         __clear_bit(X86_FEATURE_NODEID_MSR % 32, &c);
         __clear_bit(X86_FEATURE_TOPOEXT % 32, &c);
+        __clear_bit(X86_FEATURE_MWAITX % 32, &c);
         break;
 
     case 0x0000000a: /* Architectural Performance Monitor Features (Intel) */
--- a/xen/include/asm-x86/cpufeature.h
+++ b/xen/include/asm-x86/cpufeature.h
@@ -140,6 +140,7 @@
 #define X86_FEATURE_TBM         (6*32+21) /* trailing bit manipulations */
 #define X86_FEATURE_TOPOEXT     (6*32+22) /* topology extensions CPUID leafs */
 #define X86_FEATURE_DBEXT       (6*32+26) /* data breakpoint extension */
+#define X86_FEATURE_MWAITX      (6*32+29) /* MWAIT extension (MONITORX/MWAITX) 
*/
 
 /* Intel-defined CPU features, CPUID level 0x00000007:0 (ebx), word 7 */
 #define X86_FEATURE_FSGSBASE   (7*32+ 0) /* {RD,WR}{FS,GS}BASE instructions */




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