From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932786AbcAYOF7 (ORCPT ); Mon, 25 Jan 2016 09:05:59 -0500 Received: from mx1.redhat.com ([209.132.183.28]:60234 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932090AbcAYOF5 (ORCPT ); Mon, 25 Jan 2016 09:05:57 -0500 Date: Mon, 25 Jan 2016 15:05:53 +0100 From: Radim =?utf-8?Q?Krcm=C3=A1r?= To: "Wu, Feng" Cc: Paolo Bonzini , "linux-kernel@vger.kernel.org" , "kvm@vger.kernel.org" Subject: Re: [PATCH v3 1/4] KVM: Recover IRTE to remapped mode if the interrupt is not single-destination Message-ID: <20160125140552.GB21252@potion.brq.redhat.com> References: <1453254177-103002-1-git-send-email-feng.wu@intel.com> <1453254177-103002-2-git-send-email-feng.wu@intel.com> <20160121161949.GA14104@potion.brq.redhat.com> <20160122130551.GA23362@potion.brq.redhat.com> <56A6138E.9060805@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2016-01-25 12:26+0000, Wu, Feng: >> From: Paolo Bonzini [mailto:paolo.bonzini@gmail.com] On Behalf Of Paolo >> It may be necessary because IRTE writes (128 bits) are not atomic. > > IRTE is updated atomically, I added the patch to support this. Please > refer to 344cb4e0b6f3a0dbef0643eacb4946338eb228c0. I also think that SN bit is not affected by atomicity: if the IRTE could have been read half-updated while changing from posted to non-posted, then it wouldn't point to the correct PID, because its address is not within 64 bits, so the SN bit wouldn't matter. IRTE invalidation seems important in VT-d ...