From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753424AbeDRIhC (ORCPT ); Wed, 18 Apr 2018 04:37:02 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:60394 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751942AbeDRIhA (ORCPT ); Wed, 18 Apr 2018 04:37:00 -0400 Date: Wed, 18 Apr 2018 16:36:50 +0800 From: Peter Xu To: linux-kernel@vger.kernel.org Cc: Alex Williamson , Joerg Roedel , David Woodhouse Subject: Re: [PATCH 0/3] intel-iommu: fix mapping PSI missing for iommu_map() Message-ID: <20180418083650.GE14841@xz-mi> References: <20180418044130.12339-1-peterx@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20180418044130.12339-1-peterx@redhat.com> User-Agent: Mutt/1.9.1 (2017-09-22) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 18, 2018 at 12:41:27PM +0800, Peter Xu wrote: > (PSI stands for: Page Selective Invalidations) > > Intel IOMMU has the caching mode to ease emulation of the device. > When that bit is set, we need to send PSIs even for newly mapped > pages. However current driver is not fully obey the rule. E.g., > iommu_map() API will only do the mapping but it never sent the PSIs > before. That can be problematic to emulated IOMMU devices since > they'll never be able to build up the shadow page tables if without > such information. This patchset tries to fix the problem. > > Patch 1 is a tracing enhancement that helped me to triage the problem. > It might even be useful in the future. > > Patch 2 generalized a helper to notify the MAP PSIs. > > Patch 3 fixes the real problem by making sure every domain mapping > will trigger the MAP PSI notifications. > > Without the patchset, nested device assignment (assign one device > firstly to L1 guest, then to L2 guest) won't work for QEMU. After > applying the patchset, it works. > > Please review. Thanks. I even forgot to CC iommu list. I'll just repost. Sorry for the troublesome. -- Peter Xu