From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755110Ab3KUUr1 (ORCPT ); Thu, 21 Nov 2013 15:47:27 -0500 Received: from co1ehsobe003.messaging.microsoft.com ([216.32.180.186]:19815 "EHLO co1outboundpool.messaging.microsoft.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751508Ab3KUUrZ (ORCPT ); Thu, 21 Nov 2013 15:47:25 -0500 X-Forefront-Antispam-Report: CIP:70.37.183.190;KIP:(null);UIP:(null);IPV:NLI;H:mail.freescale.net;RD:none;EFVD:NLI X-SpamScore: -6 X-BigFish: VS-6(zz98dI9371I936eI542I1432I4015Izz1f42h2148h208ch1ee6h1de0h1fdah2073h2146h1202h1e76h1d1ah1d2ah1fc6hzz1de098h1de097hz2dh2a8h839h93fhd24hf0ah1288h12a5h12a9h12bdh137ah139eh13b6h1441h1504h1537h162dh1631h1758h1898h18e1h1946h19b5h1ad9h1b0ah1b2fh2222h224fh1fb3h1d0ch1d2eh1d3fh1dfeh1dffh1e23h1fe8h1ff5h2218h2216h226dh22d0h1155h) Message-ID: <1385066835.1403.489.camel@snotra.buserror.net> Subject: Re: [PATCH 0/9 v2] vfio-pci: add support for Freescale IOMMU (PAMU) From: Scott Wood To: Alex Williamson CC: Bharat Bhushan , "linux-pci@vger.kernel.org" , "agraf@suse.de" , Stuart Yoder , "iommu@lists.linux-foundation.org" , "bhelgaas@google.com" , "linuxppc-dev@lists.ozlabs.org" , "linux-kernel@vger.kernel.org" Date: Thu, 21 Nov 2013 14:47:15 -0600 In-Reply-To: <1385066603.2879.414.camel@ul30vt.home> References: <1384838233-24847-1-git-send-email-Bharat.Bhushan@freescale.com> <1384973243.2879.361.camel@ul30vt.home> <6A3DF150A5B70D4F9B66A25E3F7C888D0721D9AC@039-SN2MPN1-012.039d.mgd.msft.net> <1385066603.2879.414.camel@ul30vt.home> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.6.4-0ubuntu1 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-OriginatorOrg: freescale.com X-FOPE-CONNECTOR: Id%0$Dn%*$RO%0$TLS%0$FQDN%$TlsDn% X-FOPE-CONNECTOR: Id%0$Dn%FREESCALE.MAIL.ONMICROSOFT.COM$RO%1$TLS%0$FQDN%$TlsDn% Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2013-11-21 at 13:43 -0700, Alex Williamson wrote: > On Thu, 2013-11-21 at 11:20 +0000, Bharat Bhushan wrote: > > > > > -----Original Message----- > > > From: Alex Williamson [mailto:alex.williamson@redhat.com] > > > Sent: Thursday, November 21, 2013 12:17 AM > > > To: Bhushan Bharat-R65777 > > > Cc: joro@8bytes.org; bhelgaas@google.com; agraf@suse.de; Wood Scott-B07421; > > > Yoder Stuart-B08248; iommu@lists.linux-foundation.org; linux- > > > pci@vger.kernel.org; linuxppc-dev@lists.ozlabs.org; linux- > > > kernel@vger.kernel.org; Bhushan Bharat-R65777 > > > Subject: Re: [PATCH 0/9 v2] vfio-pci: add support for Freescale IOMMU (PAMU) > > > > > > Is VFIO_IOMMU_PAMU_GET_MSI_BANK_COUNT per aperture (ie. each vfio user has > > > $COUNT regions at their disposal exclusively)? > > > > Number of msi-bank count is system wide and not per aperture, But will be setting windows for banks in the device aperture. > > So say if we are direct assigning 2 pci device (both have different iommu group, so 2 aperture in iommu) to VM. > > Now qemu can make only one call to know how many msi-banks are there but it must set sub-windows for all banks for both pci device in its respective aperture. > > I'm still confused. What I want to make sure of is that the banks are > independent per aperture. For instance, if we have two separate > userspace processes operating independently and they both chose to use > msi bank zero for their device, that's bank zero within each aperture > and doesn't interfere. Or another way to ask is can a malicious user > interfere with other users by using the wrong bank. Thanks, They can interfere. With this hardware, the only way to prevent that is to make sure that a bank is not shared by multiple protection contexts. For some of our users, though, I believe preventing this is less important than the performance benefit. -Scott