KVM: SVM: copy instruction bytes from VMCB

In case of a nested page fault or an intercepted #PF newer SVM
implementations provide a copy of the faulting instruction bytes
in the VMCB.
Use these bytes to feed the instruction emulator and avoid the costly
guest instruction fetch in this case.

Signed-off-by: Andre Przywara <andre.przywara@amd.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

arch/x86/include/asm/svm.h

@@ -83,7 +83,9 @@ struct __attribute__ ((__packed__)) vmcb_control_area {
 	u32 clean;
 	u32 reserved_5;
 	u64 next_rip;
-	u8 reserved_6[816];
+	u8 insn_len;
+	u8 insn_bytes[15];
+	u8 reserved_6[800];
 };