From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH 12/13] KVM: SVM: Add checks for IO instructions Date: Thu, 31 Mar 2011 11:18:28 +0200 Message-ID: <4D9446E4.2050508@redhat.com> References: <1301309210-11120-1-git-send-email-joerg.roedel@amd.com> <1301309210-11120-13-git-send-email-joerg.roedel@amd.com> <4D907EDC.1050607@redhat.com> <20110331071440.GQ2085@amd.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , "kvm@vger.kernel.org" To: "Roedel, Joerg" Return-path: Received: from mx1.redhat.com ([209.132.183.28]:16255 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752356Ab1CaJSd (ORCPT ); Thu, 31 Mar 2011 05:18:33 -0400 In-Reply-To: <20110331071440.GQ2085@amd.com> Sender: kvm-owner@vger.kernel.org List-ID: On 03/31/2011 09:14 AM, Roedel, Joerg wrote: > On Mon, Mar 28, 2011 at 08:28:12AM -0400, Avi Kivity wrote: > > The spec indicates we need to check the TSS and IOPL based permissions > > before the intercept (vmx agrees). With the code as is, it happens > > afterwards. > > > > One way to do this is to have an ExtraChecks bit in the opcode::flags. > > Then opcode::u.xcheck->perms() is the pre-intercept check and > > opcode::u.xcheck->execute() is the post-intercept execution. Should > > work for monitor/mwait/rdtsc(p)/rdpmc/other crap x86 throws at us. > > Okay, as you suggested, I put these checks into the instruction emulator > and let the hard work of implementing per-arch checks to the nested-vmx > people ;) > I doubt that this makes the opcode-tables more readable, but lets see :) I think we're miscommunicating. I'm talking about x86 checks, not virt vendor specific checks. For example, the flow for IOIO would be: #UD check (lock prefix) PE/IOPL/CPL/VM check TSS bitmap check (can cause #PF) Intercept check Operand segment check Possible #PF Execution We need to make sure the TSS bitmap check happens before the intercept, so we need to split ->execute() into two. -- error compiling committee.c: too many arguments to function