From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gleb Natapov Subject: Re: [RFC PATCH] emulator: Fix task switch into/out of VM86 Date: Tue, 10 Jan 2012 12:17:36 +0200 Message-ID: <20120110101736.GL2167@redhat.com> References: <1326139810-5448-1-git-send-email-kwolf@redhat.com> <20120110090122.GI2167@redhat.com> <4F0C04A6.1080705@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: kvm@vger.kernel.org To: Kevin Wolf Return-path: Received: from mx1.redhat.com ([209.132.183.28]:62113 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754929Ab2AJKRh (ORCPT ); Tue, 10 Jan 2012 05:17:37 -0500 Received: from int-mx11.intmail.prod.int.phx2.redhat.com (int-mx11.intmail.prod.int.phx2.redhat.com [10.5.11.24]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id q0AAHbrB020904 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Tue, 10 Jan 2012 05:17:37 -0500 Content-Disposition: inline In-Reply-To: <4F0C04A6.1080705@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On Tue, Jan 10, 2012 at 10:28:06AM +0100, Kevin Wolf wrote: > Am 10.01.2012 10:01, schrieb Gleb Natapov: > > On Mon, Jan 09, 2012 at 09:10:10PM +0100, Kevin Wolf wrote: > >> * This works with VMX, but with SVM I have an additional problem: When > >> trying to exit VM86 (usually by an exception) through a task gate in > >> the IDT, the code runs into the reason = TASK_SWITCH_CALL path. I > >> searched a bit in the documentation, but didn't find any obvious way > >> to fix this. > >> > > Hmm, so exit_int_info is invalid during task switch exit even though > > task switch was caused by an exception. I wonder is this the case when > > vcpu is not in vm86 mode too? > > No idea, I would have to try it out. > IIRC (again) 32 bit Linux kernel configures double fault as a task gate, so causing #DF on 32 bit kernel guest should be enough to test that. -- Gleb.