From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1162806AbdAFJXL (ORCPT ); Fri, 6 Jan 2017 04:23:11 -0500 Received: from foss.arm.com ([217.140.101.70]:39938 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1162769AbdAFJUf (ORCPT ); Fri, 6 Jan 2017 04:20:35 -0500 Subject: Re: [PATCH v6 17/18] vfio/type1: Check MSI remapping at irq domain level To: Auger Eric , Bharat Bhushan , "eric.auger.pro@gmail.com" , "christoffer.dall@linaro.org" , "robin.murphy@arm.com" , "alex.williamson@redhat.com" , "will.deacon@arm.com" , "joro@8bytes.org" , "tglx@linutronix.de" , "jason@lakedaemon.net" , "linux-arm-kernel@lists.infradead.org" References: <1483643086-2883-1-git-send-email-eric.auger@redhat.com> <1483643086-2883-18-git-send-email-eric.auger@redhat.com> Cc: "kvm@vger.kernel.org" , "drjones@redhat.com" , "linux-kernel@vger.kernel.org" , "pranav.sawargaonkar@gmail.com" , "iommu@lists.linux-foundation.org" , "punit.agrawal@arm.com" , Diana Madalina Craciun , "gpkulkarni@gmail.com" , "shankerd@codeaurora.org" , "geethasowjanya.akula@gmail.com" From: Marc Zyngier Organization: ARM Ltd Message-ID: <845d7167-6734-03c9-4df6-2f82f1627dbc@arm.com> Date: Fri, 6 Jan 2017 09:20:29 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Icedove/45.5.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/01/17 09:08, Auger Eric wrote: > Hi Bharat > > On 06/01/2017 09:50, Bharat Bhushan wrote: >> Hi Eric, >> >>> -----Original Message----- >>> From: Eric Auger [mailto:eric.auger@redhat.com] >>> Sent: Friday, January 06, 2017 12:35 AM >>> To: eric.auger@redhat.com; eric.auger.pro@gmail.com; >>> christoffer.dall@linaro.org; marc.zyngier@arm.com; >>> robin.murphy@arm.com; alex.williamson@redhat.com; >>> will.deacon@arm.com; joro@8bytes.org; tglx@linutronix.de; >>> jason@lakedaemon.net; linux-arm-kernel@lists.infradead.org >>> Cc: kvm@vger.kernel.org; drjones@redhat.com; linux- >>> kernel@vger.kernel.org; pranav.sawargaonkar@gmail.com; >>> iommu@lists.linux-foundation.org; punit.agrawal@arm.com; Diana Madalina >>> Craciun ; gpkulkarni@gmail.com; >>> shankerd@codeaurora.org; Bharat Bhushan ; >>> geethasowjanya.akula@gmail.com >>> Subject: [PATCH v6 17/18] vfio/type1: Check MSI remapping at irq domain >>> level >>> >>> In case the IOMMU translates MSI transactions (typical case on ARM), we >>> check MSI remapping capability at IRQ domain level. Otherwise it is checked >>> at IOMMU level. >>> >>> At this stage the arm-smmu-(v3) still advertise the >>> IOMMU_CAP_INTR_REMAP capability at IOMMU level. This will be removed >>> in subsequent patches. >>> >>> Signed-off-by: Eric Auger >>> >>> --- >>> >>> v6: rewrite test >>> --- >>> drivers/vfio/vfio_iommu_type1.c | 9 ++++++--- >>> 1 file changed, 6 insertions(+), 3 deletions(-) >>> >>> diff --git a/drivers/vfio/vfio_iommu_type1.c >>> b/drivers/vfio/vfio_iommu_type1.c index b473ef80..fa0b5c4 100644 >>> --- a/drivers/vfio/vfio_iommu_type1.c >>> +++ b/drivers/vfio/vfio_iommu_type1.c >>> @@ -40,6 +40,7 @@ >>> #include >>> #include >>> #include >>> +#include >>> >>> #define DRIVER_VERSION "0.2" >>> #define DRIVER_AUTHOR "Alex Williamson >>> " >>> @@ -1208,7 +1209,7 @@ static int vfio_iommu_type1_attach_group(void >>> *iommu_data, >>> struct vfio_domain *domain, *d; >>> struct bus_type *bus = NULL, *mdev_bus; >>> int ret; >>> - bool resv_msi; >>> + bool resv_msi, msi_remap; >>> phys_addr_t resv_msi_base; >>> >>> mutex_lock(&iommu->lock); >>> @@ -1284,8 +1285,10 @@ static int vfio_iommu_type1_attach_group(void >>> *iommu_data, >>> INIT_LIST_HEAD(&domain->group_list); >>> list_add(&group->next, &domain->group_list); >>> >>> - if (!allow_unsafe_interrupts && >>> - !iommu_capable(bus, IOMMU_CAP_INTR_REMAP)) { >>> + msi_remap = resv_msi ? irq_domain_check_msi_remap() : >> >> There can be multiple interrupt-controller, at-least theoretically it is possible and not sure practically it exists and supported, where not all may support IRQ_REMAP. If that is the case be then should we check for IRQ-REMAP for that device-bus irq-domain? >> > I mentioned in the cover letter that the approach was defensive and > rough today. As soon as we detect an MSI controller in the platform that > has no support for MSI remapping we flag the assignment as unsafe. I > think this approach was agreed on the ML. Such rough assessment was used > in the past on x86. > > I am reluctant to add more complexity at that stage. This can be > improved latter I think when such platforms show up. I don't think this is worth it. If the system is so broken that the designer cannot make up their mind about device isolation, too bad. People will either disable the non-isolating MSI controller altogether, or force the unsafe flag. Thanks, M. -- Jazz is not dead. It just smells funny...