From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kiszka Subject: Re: [PATCH] KVM: unbreak userspace that does not sets tss address Date: Mon, 07 Mar 2011 17:23:02 +0100 Message-ID: <4D750666.5040008@siemens.com> References: <20110307151936.GA10151@redhat.com> <4D74FE88.9060708@siemens.com> <20110307162030.GB22987@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: "kvm@vger.kernel.org" , "avi@redhat.com" , "mtosatti@redhat.com" To: Gleb Natapov Return-path: Received: from goliath.siemens.de ([192.35.17.28]:29752 "EHLO goliath.siemens.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751957Ab1CGQXQ (ORCPT ); Mon, 7 Mar 2011 11:23:16 -0500 In-Reply-To: <20110307162030.GB22987@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On 2011-03-07 17:20, Gleb Natapov wrote: > On Mon, Mar 07, 2011 at 04:49:28PM +0100, Jan Kiszka wrote: >> On 2011-03-07 16:19, Gleb Natapov wrote: >>> Commit 6440e5967bc broke old userspaces that do not set tss address >>> before entering vcpu. Unbreak it by setting tss address to a safe >>> value on the first vcpu entry. New userspaces should set tss address, >>> so print warning in case it doesn't. >> >> Wouldn't allow runtime warnings but wouldn't it be cleaner otherwise to >> start vcpus with a default tss address like that, ie. add the logic to >> vmx_create_vcpu? >> > Userspace can create VCPU before setting tss address. We will have to > have logic that removes default tss slot in set_tss_address callback. > Also this default slot may prevent userspace from creating another slot > at this physical address which is perfectly legitimate thing for userspace > to do. Ah, ok. I thought you could simple override the tss slot by calling the corresponding service again. Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux