Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754654AbbFKO0A (ORCPT ); Thu, 11 Jun 2015 10:26:00 -0400 Received: from cantor2.suse.de ([195.135.220.15]:55015 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754606AbbFKOZ5 (ORCPT ); Thu, 11 Jun 2015 10:25:57 -0400 Date: Thu, 11 Jun 2015 16:25:54 +0200 From: Joerg Roedel To: David Woodhouse Cc: Joerg Roedel , iommu@lists.linux-foundation.org, zhen-hual@hp.com, bhe@redhat.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/4] iommu/vt-d: Don't consider copied context entries as present Message-ID: <20150611142554.GG16345@suse.de> References: <1434030463-942-1-git-send-email-joro@8bytes.org> <1434030463-942-3-git-send-email-joro@8bytes.org> <1434031622.3907.40.camel@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1434031622.3907.40.camel@infradead.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1250 Lines: 31 On Thu, Jun 11, 2015 at 03:07:02PM +0100, David Woodhouse wrote: > On Thu, 2015-06-11 at 15:47 +0200, Joerg Roedel wrote: > > From: Joerg Roedel > > > > Hide the copied context entries from the IOMMU driver by > > considering them as non-present. This is implemented by > > setting the first AVL bit (bit 67) in the context entry to > > one. If this bit is set, the context_present() function > > returns false. > > > > Signed-off-by: Joerg Roedel > > In the extended context entry, bit 67 is the PGE bit. There are no bits > which are available to software, to my knowledge. Okay, reading the VT-d spec again, the extended context-entry table seem to exist in parallel to the current context-entry table, right? So this patch should still work, even with extended entries present. If that's true, then we only need to consider the kdump case while setting up the extended context table entry (which means don't trust any content that is already there). Joerg -- 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/