From mboxrd@z Thu Jan 1 00:00:00 1970 From: bugzilla-daemon@bugzilla.kernel.org Subject: [Bug 65561] KVM:Entry failed on Single stepping sti instruction Date: Sat, 24 May 2014 12:26:41 +0000 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit To: kvm@vger.kernel.org Return-path: Received: from mail.kernel.org ([198.145.19.201]:39667 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750748AbaEXM0o (ORCPT ); Sat, 24 May 2014 08:26:44 -0400 Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 9F2D4203E9 for ; Sat, 24 May 2014 12:26:43 +0000 (UTC) Received: from bugzilla1.web.kernel.org (bugzilla1.web.kernel.org [172.20.200.51]) by mail.kernel.org (Postfix) with ESMTP id 7927420272 for ; Sat, 24 May 2014 12:26:41 +0000 (UTC) In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: https://bugzilla.kernel.org/show_bug.cgi?id=65561 --- Comment #28 from Paolo Bonzini --- As Jatin said, most of the time the emulator is not invoked for instructions that require intervention of the hypervisor. Instead, the processor provides enough "pre-decoded" information about the instruction, so KVM doesn't need to do it all again in the emulator. Instructions that invoke the emulator are those that invoke ports or memory-mapped devices. However "out" is a fast path, so it doesn't invoke the emulator. You see it all the time because the kernel uses it to interact with many devices (such as the keyboard controller, disk controller or network cards). I suggest that you try reproducing the problem with "sti". The one with "out" is known and documented in the source code. -- You are receiving this mail because: You are watching the assignee of the bug.