From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gleb Natapov Subject: Re: [PATCH 2/3] KVM: x86: Save&restore interrupt shadow mask Date: Wed, 17 Feb 2010 11:05:52 +0200 Message-ID: <20100217090552.GL2995@redhat.com> References: <0bc4d8c46c0868cff70568bb5ee6df25162ddab6.1266227138.git.jan.kiszka@siemens.com> <20100217003941.GA1110@amt.cnet> <4B7BA374.4040102@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Marcelo Tosatti , Jan Kiszka , Avi Kivity , kvm To: Zachary Amsden Return-path: Received: from mx1.redhat.com ([209.132.183.28]:12495 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934176Ab0BQJF6 (ORCPT ); Wed, 17 Feb 2010 04:05:58 -0500 Content-Disposition: inline In-Reply-To: <4B7BA374.4040102@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On Tue, Feb 16, 2010 at 10:06:12PM -1000, Zachary Amsden wrote: > On 02/16/2010 02:39 PM, Marcelo Tosatti wrote: > >On Mon, Feb 15, 2010 at 10:45:42AM +0100, Jan Kiszka wrote: > >>The interrupt shadow created by STI or MOV-SS-like operations is part of > >>the VCPU state and must be preserved across migration. Transfer it in > >>the spare padding field of kvm_vcpu_events.interrupt. > > STI and MOV-SS interrupt shadow are both treated differently by > hardware. Any attempt to unify them into a single field is wrong, > especially so in a hardware virtualization context, where they are > actually represented by different fields in the undocumented but > nevertheless extant format that can be inferred from the hardware > virtualization context used by specific vendors. > The problem is SVM doesn't distinguish between those two. But we shouldn't design out interfaces based on SVM brokenness. -- Gleb.