Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755819Ab3H2HXO (ORCPT ); Thu, 29 Aug 2013 03:23:14 -0400 Received: from nat28.tlf.novell.com ([130.57.49.28]:42799 "EHLO nat28.tlf.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753300Ab3H2HXM convert rfc822-to-8bit (ORCPT ); Thu, 29 Aug 2013 03:23:12 -0400 Message-Id: <521F12FC02000078000EF503@nat28.tlf.novell.com> X-Mailer: Novell GroupWise Internet Agent 12.0.2 Date: Thu, 29 Aug 2013 08:23:08 +0100 From: "Jan Beulich" To: Cc: "Bjorn Helgaas" , "xen-devel" , "Feng Jin" , "Sucheta Chakraborty" , "linux-kernel@vger.kernel.org" , "linux-pci@vger.kernel.org" Subject: Re: [Xen-devel] [PATCH 2/3 v3] Refactor MSI restore call-chain to drop unnecessary argument References: <521EB76B.8090903@oracle.com> In-Reply-To: <521EB76B.8090903@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8BIT Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1440 Lines: 38 >>> On 29.08.13 at 04:52, Zhenzhong Duan wrote: > But in initial domain (aka priviliged guest), it's different. > Driver init call graph under initial domain: > driver_init-> > msix_capability_init-> > msix_program_entries-> > msix_mask_irq-> > entry->masked = 1 > request_irq-> > __setup_irq-> > irq_startup-> > __startup_pirq-> > EVTCHNOP_bind_pirq hypercall (trap into Xen) > [Xen:] > pirq_guest_bind-> > startup_msi_irq-> > unmask_msi_irq-> > msi_set_mask_bit-> > entry->msi_attrib.masked = 0 > > So entry->msi_attrib.masked in xen side always has newest value. entry->masked > in initial domain is untouched and is 1 after msix_capability_init. And as said several times before - Linux shouldn't be touching the MSI-X table at all during initial setup or resume (it should in particular not rely on such accesses to not fault, as being a privilege violation); all it needs to do is update its software state. Hence fiddling with default_restore_msi_irqs() seems the wrong approach towards solving the problem. Jan -- 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/