From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pierre Morel Subject: Re: [PATCH v1] iommu/s390: Declare s390 iommu reserved regions Date: Thu, 17 Jan 2019 14:02:12 +0100 Message-ID: References: <1547573850-9459-1-git-send-email-pmorel@linux.ibm.com> <5FC3163CFD30C246ABAA99954A238FA83928BF16@lhreml524-mbs.china.huawei.com> Reply-To: pmorel@linux.ibm.com Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: <5FC3163CFD30C246ABAA99954A238FA83928BF16@lhreml524-mbs.china.huawei.com> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org To: Shameerali Kolothum Thodi , "gerald.schaefer@de.ibm.com" Cc: "joro@8bytes.org" , "linux-s390@vger.kernel.org" , "iommu@lists.linux-foundation.org" , "linux-kernel@vger.kernel.org" , "alex.williamson@redhat.com" , "walling@linux.ibm.com" List-Id: iommu@lists.linux-foundation.org On 17/01/2019 10:23, Shameerali Kolothum Thodi wrote: > Hi Pierre, > >> -----Original Message----- >> From: Pierre Morel [mailto:pmorel@linux.ibm.com] >> Sent: 15 January 2019 17:37 >> To: gerald.schaefer@de.ibm.com >> Cc: joro@8bytes.org; linux-s390@vger.kernel.org; >> iommu@lists.linux-foundation.org; linux-kernel@vger.kernel.org; >> alex.williamson@redhat.com; Shameerali Kolothum Thodi >> ; walling@linux.ibm.com >> Subject: [PATCH v1] iommu/s390: Declare s390 iommu reserved regions >> >> The s390 iommu can only allow DMA transactions between the zPCI device >> entries start_dma and end_dma. >> >> Let's declare the regions before start_dma and after end_dma as >> reserved regions using the appropriate callback in iommu_ops. >> >> The reserved region may later be retrieved from sysfs or from >> the vfio iommu internal interface. > > Just in case you are planning to use the sysfs interface to retrieve the valid > regions, and intend to use that in Qemu vfio path, please see the discussion > here [1] (If you haven't seen this already) > > Thanks, > Shameer > > [1] https://lists.gnu.org/archive/html/qemu-devel/2017-11/msg03651.html > >> This seems to me related with the work Shameer has started on >> vfio_iommu_type1 so I add Alex and Shameer to the CC list. >> >> Pierre Morel (1): >> iommu/s390: Declare s390 iommu reserved regions >> >> drivers/iommu/s390-iommu.c | 29 +++++++++++++++++++++++++++++ >> 1 file changed, 29 insertions(+) >> >> -- >> 2.7.4 > Thanks Shameer, Interesting discussion indeed. AFAIK the patch series you are working on will provide a way to retrieve the reserved region through the VFIO IOMMU interface, using capabilities in the VFIO_IOMMU_GET_INFO. Before this patch, the iommu_type1 was not able to retrieve the forbidden region from the s390_iommu. See this patch is a contribution, so that these regions will appear in the reserved list when the VFIO_IOMM_GET_INFO will be able to report the information. I am expecting to be able to to retrieve this information from the VFIO_IOMMU_GET_INFO syscall as soon as it is available. Regards, Pierre -- Pierre Morel Linux/KVM/QEMU in Böblingen - Germany