x86: kvm: use alternatives for VMCALL vs. VMMCALL if kernel text is read-only
[pandora-kernel.git] / arch / x86 / include / asm / kvm_para.h
index 734c376..9f0a680 100644 (file)
@@ -91,15 +91,21 @@ struct kvm_vcpu_pv_apf_data {
 
 #ifdef __KERNEL__
 #include <asm/processor.h>
+#include <asm/alternative.h>
 
 extern void kvmclock_init(void);
 extern int kvm_register_clock(char *txt);
 
 
-/* This instruction is vmcall.  On non-VT architectures, it will generate a
- * trap that we will then rewrite to the appropriate instruction.
+#ifdef CONFIG_DEBUG_RODATA
+#define KVM_HYPERCALL \
+        ALTERNATIVE(".byte 0x0f,0x01,0xc1", ".byte 0x0f,0x01,0xd9", X86_FEATURE_VMMCALL)
+#else
+/* On AMD processors, vmcall will generate a trap that we will
+ * then rewrite to the appropriate instruction.
  */
 #define KVM_HYPERCALL ".byte 0x0f,0x01,0xc1"
+#endif
 
 /* For KVM hypercalls, a three-byte sequence of either the vmrun or the vmmrun
  * instruction.  The hypervisor may replace it with something else but only the