x86/oprofile: op_model_athlon.c: fix counter reset when reenabling IBS OP

Signed-off-by: Robert Richter <robert.richter@amd.com>
Cc: oprofile-list <oprofile-list@lists.sourceforge.net>
Cc: Barry Kasindorf <barry.kasindorf@amd.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/oprofile/op_model_athlon.c

@@ -251,6 +251,7 @@ op_amd_handle_ibs(struct pt_regs * const regs,
 						(unsigned int *)&ibs_op,
 						IBS_OP_BEGIN);
 			rdmsr(MSR_AMD64_IBSOPCTL, low, high);
+			high = 0;
 			low &= ~IBS_OP_LOW_VALID_BIT;
 			low |= IBS_OP_LOW_ENABLE;
 			wrmsr(MSR_AMD64_IBSOPCTL, low, high);