From mboxrd@z Thu Jan 1 00:00:00 1970 From: Auger Eric Subject: Re: [RFC PATCH v2 2/5] iommu/virtio-iommu: Add probe request Date: Fri, 19 Jan 2018 18:22:30 +0100 Message-ID: References: <20171117185211.32593-1-jean-philippe.brucker@arm.com> <20171117185211.32593-3-jean-philippe.brucker@arm.com> <5b236aaa-4abb-2cac-1c74-f8137a0c2244@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: Jean-Philippe Brucker , "iommu@lists.linux-foundation.org" , "devel@acpica.org" , "linux-acpi@vger.kernel.org" , "kvm@vger.kernel.org" , "kvmarm@lists.cs.columbia.edu" , "virtualization@lists.linux-foundation.org" , "virtio-dev@lists.oasis-open.org" Cc: "Jayachandran.Nair@cavium.com" , Lorenzo Pieralisi , "ashok.raj@intel.com" , "mst@redhat.com" , Marc Zyngier , Will Deacon , "rjw@rjwysocki.net" , "robert.moore@intel.com" , "lv.zheng@intel.com" , Sudeep Holla , "lenb@kernel.org" , Robin Murphy , "joro@8bytes.org" , "hanjun.guo@linaro.org" List-Id: virtualization@lists.linuxfoundation.org Hi Jean-Philippe, On 19/01/18 17:21, Jean-Philippe Brucker wrote: > On 16/01/18 23:26, Auger Eric wrote: > [...] >>> + switch (mem->subtype) { >>> + case VIRTIO_IOMMU_RESV_MEM_T_MSI: >>> + region = iommu_alloc_resv_region(addr, size, prot, >>> + IOMMU_RESV_MSI); >> if (!region) >> return -ENOMEM; >>> + break; >>> + case VIRTIO_IOMMU_RESV_MEM_T_RESERVED: >>> + default: >>> + region = iommu_alloc_resv_region(addr, size, 0, >>> + IOMMU_RESV_RESERVED); >> same. > > I'll add them, thanks > >> There is another issue related to the exclusion of iovas belonging to >> reserved regions. Typically on x86, when attempting to run >> virtio-blk-pci with iommu I eventually saw the driver using iova >> belonging to the IOAPIC regions to map phys addr and this stalled qemu >> with a drown trace: >> >> "virtio: bogus descriptor or out of resources" >> >> those regions need to be excluded from the iova allocator. This was >> resolved by adding >> if (iommu_dma_init_domain(domain, >> vdev->viommu->geometry.aperture_start, >> vdev->viommu->geometry.aperture_end, >> dev)) >> in viommu_attach_dev() > > The most recent hack for x86 [1] does call iommu_dma_init_domain() in > attach_dev(). Is it buggy? Oh OK. Actually I have never used that branch and in my version the last arg of iommu_dma_init_domain was NULL hence the issue. But I was thinking more generally that care must be taken to exclude all those regions. Thanks Eric > > We probably shouldn't call iommu_dma_init_domain() unconditionally > (outside of CONFIG_X86 that is), since it's normally done by the arch > (arch/arm64/mm/dma-mapping.c) > > Thanks, > Jean > > [1] > http://www.linux-arm.org/git?p=linux-jpb.git;a=commitdiff;h=e910e224b58712151dda06df595a53ff07edef63 > on branch virtio-iommu/v0.5-x86 >