From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Auger Subject: Re: [PATCH v5 0/4] vfio: type1: support for ARM SMMUS with VFIO_IOMMU_TYPE1 Date: Fri, 06 Mar 2015 10:04:22 +0100 Message-ID: <54F96D96.8040207@linaro.org> References: <1425485274-5709-1-git-send-email-b.reynal@virtualopensystems.com> <1425491104.5200.268.camel@redhat.com> <54F893C3.6020006@linaro.org> <1425589915.5200.336.camel@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1425589915.5200.336.camel-H+wXaHxf7aLQT0dZR+AlfA@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: Alex Williamson Cc: Will Deacon , iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, tech-lrHrjnjw1UfHK3s98zE1ajGjJy/sRE9J@public.gmane.org, kvmarm-FPEHb7Xf0XXUo1n7N8X6UoWGPAHP3yOg@public.gmane.org List-Id: iommu@lists.linux-foundation.org On 03/05/2015 10:11 PM, Alex Williamson wrote: > On Thu, 2015-03-05 at 18:34 +0100, Eric Auger wrote: >> Hi All, >> >> Ironically, since the correction of the IOMMU_CAP_CACHE_COHERENCY bug >> (https://lkml.org/lkml/2015/1/29/514) in vfio_iommu_type1.c, my Calxeda >> Midway VFIO use case is not working anymore. This is also observable >> when I do not apply at all the whole [PATCH v5 0/4] vfio: type1: support >> for ARM SMMUS with VFIO_IOMMU_TYPE1 series. >> >> My understanding is this series should not be requested for me since my >> xgmac device does not care about the XN attribute. > > This also raises the concern that we're continuing to put optional > features as prerequisites to base vfio-platform support and creating > self-induced stalls at getting anything upstream :-\ Thanks, Dear all, Thanks Alex, Will for your inputs on this topic. Yes to me "vfio: type1: support for ARM SMMUS with VFIO_IOMMU_TYPE1" is not a direct dependency of vfio-platform driver although I understand Baptiste needs it to test with PL330 device. On my side I can test vfio-platform driver without it, assigning the Midway Calxeda xgmac. Also if I am not wrong the title of the series now does not really reflect anymore what the series aims at. since "[PATCH v3 2/6] vfio: type1: support for ARM SMMUs" withdrawal, the series now "only" aims at supporting the VFIO_DMA_MAP_FLAG_NOEXEC flag. However with this issue of IOMMU_CACHE always set along with arm-smmu, there is a need for an adaptation of either vfio_iommu_type1 or arm-smmu since the integrated pieces are not functional. On top of the dma-coherent property of the *master*, should not we also query the cache-coherent property of the interconnect downstream to the smmu? How can we progress quickly on this topic? is it acceptable to return false on arm_smmu_capable(IOMMU_CAP_CACHE_COHERENCY) as a quick hack? As a longer term solution, would it make sense to add a user flag at VFIO user API level to turn the IOMMU_CACHE on? Best Regards Eric Best Regards Eric Best Regards Eric > > Alex >