From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: [PATCH] iommu/amd: Fix unity mapping initialization race Date: Mon, 11 Jul 2016 09:19:59 +0200 Message-ID: <20160711071959.GB12639@8bytes.org> References: <1467820838-5059-1-git-send-email-joro@8bytes.org> <57823445.1020808@iommu.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <57823445.1020808-6ukY98dZOFrYtjvyW6yDsg@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Wan Zongshun Cc: iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Joerg Roedel , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, stable-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: iommu@lists.linux-foundation.org On Sun, Jul 10, 2016 at 07:40:53PM +0800, Wan Zongshun wrote: > Do you mean we need enable the V and TV bits to DTE entry after all > DTEs tables were initialized completely? Yes, this is what my patch does and what fixes the bug that was reported on machines which have unity-mapping entries. > I checked this function 'init_device_table_dma', and find it just set > V and TV bit, to set translation info valid and DTE bits127:1 valid. Right, if no other bits are set this blocks all DMA from the gives device-id. > So I just think all things it should to do are to allow DMA access, > GPA-to-SPA translation should be active, why you add function > comments below is to not allow DMA access and suppress all page > faults? > > /* > * Init the device table to not allow DMA access for devices and > * suppress all page faults > */ Yeah, that comment needs to be updated. Not all DMA is blocked and page-faults are not suppressed at all. Thanks for noticing. Joerg