Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759889AbXH1SN2 (ORCPT ); Tue, 28 Aug 2007 14:13:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752306AbXH1SNU (ORCPT ); Tue, 28 Aug 2007 14:13:20 -0400 Received: from ozlabs.org ([203.10.76.45]:44948 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751289AbXH1SNT (ORCPT ); Tue, 28 Aug 2007 14:13:19 -0400 Subject: Re: [PATCH 2/3] Refactor hypercall infrastructure From: Rusty Russell To: Anthony Liguori Cc: kvm-devel@lists.sourceforge.net, Avi Kivity , Ingo Molnar , Dor Laor , linux-kernel@vger.kernel.org In-Reply-To: <11882278082826-git-send-email-aliguori@us.ibm.com> References: <11882278064002-git-send-email-aliguori@us.ibm.com> <1188227808405-git-send-email-aliguori@us.ibm.com> <11882278082826-git-send-email-aliguori@us.ibm.com> Content-Type: text/plain Date: Wed, 29 Aug 2007 04:12:57 +1000 Message-Id: <1188324777.5531.73.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.10.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1370 Lines: 35 On Mon, 2007-08-27 at 10:16 -0500, Anthony Liguori wrote: > This patch refactors the current hypercall infrastructure to better support live > migration and SMP. It eliminates the hypercall page by trapping the UD > exception that would occur if you used the wrong hypercall instruction for the > underlying architecture and replacing it with the right one lazily. It also reduces the number of hypercall args, which you don't mention here. > + er = emulate_instruction(&svm->vcpu, kvm_run, 0, 0); > + > + /* we should only succeed here in the case of hypercalls which > + cannot generate an MMIO event. MMIO means that the emulator > + is mistakenly allowing an instruction that should generate > + a UD fault so it's a bug. */ > + BUG_ON(er == EMULATE_DO_MMIO); This seems... unwise. Firstly we know our emulator is incomplete. Secondly an SMP guest can exploit this to crash the host. (Code is in two places). > +#define KVM_HYPERCALL ".byte 0x0f,0x01,0xc1" A nice big comment would be nice here, I think. Note that this is big enough for both "int $0x1f" and "sysenter", so I'm happy. Cheers, Rusty. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/