On 13/09/17 18:38, valmiki wrote: > On 9/13/2017 6:50 AM, Jean-Philippe Brucker wrote: >> Hi Valmiki, >> >> On 12/09/17 19:01, valmiki wrote: >>> Hi, as per VFIO documentation i see that we need to see >>> "/sys/bus/pci/devices/0000:06:0d.0/iommu_group" in order to find group >>> in which PCI bus is attached. >>> But as per drivers/pci/pci-sysfs.c in static struct attribute >>> *pci_dev_attrs[], i don't see any such attribute. >> >> This iommu_group attribute is created by >> drivers/iommu/iommu.c:iommu_group_add_device. It is a symbolic link to >> /sys/kernel/iommu_groups/<group>. >> >>> I tried enabling SMMUv2 driver and SMMU for PCIe node on our SOC, but >>> this file doesn't show up and also in /sys/kernel/iommu_group i do not >>> see "/sys/kernel/iommu_groups/17/devices/0000:00:1f.00" file, i see only >>> PCIe root port device tree node in that group and not individual buses. >>> So on ARM64 for showing these paths i.e show specific to each bus, does >>> SMMU need any particular confguration (we have SMMUv2) > Do we need any specific kernel configuration ? >> >> I don't think so. If you're able to see the root complex in an IOMMU >> group, then the configuration is probably fine. Could you provide a little >> more information about your system, for example lspci along with "find >> /sys/kernel/iommu_groups/*/devices/*"? >> > Here is the log: > root@:~# lspci > 00:00.0 PCI bridge: Corporation Device a023 > 01:00.0 Memory controller: Corporation Device a024 > root@:~# find /sys/kernel/iommu_groups/*/devices/* > /sys/kernel/iommu_groups/0/devices/ad0c0000.pcie > /sys/kernel/iommu_groups/1/devices/ad0f0000.spi > /sys/kernel/iommu_groups/2/devices/adc70000.sdhci > /sys/kernel/iommu_groups/3/devices/ad9d0000.usb0 > root@:~# >> Ideally, each PCIe device will be in its own IOMMU group. So you shouldn't >> have each bus in a group, but rather one device per group. Linux puts >> multiple devices in a group if the IOMMU cannot properly isolate them. In >> general it's not something you want in your system, because all devices in >> a group will have the same address space and cannot be passed to a guest >> separately. >> > So i don't see separate group per pci device.When you say one pci device > per group, when does smmu creates one group per pci device ? > As per boot log i see that smmu drvier gets probed first and then pcie > root port driver, so how will smmu know number of pci devices present > downstream and create a group for each device ? (I'm assuming you're using device-tree since you mentioned it in your initial post.) Are you using the iommu-map property in your root complex node? The "iommus" property in device-tree nodes defines one or more static SIDs of a device, and doesn't work with PCI. iommu-map is a wildcard for the whole PCI bus. It defines how PCI Requester IDs are translated to SIDs. See Documentation/devicetree/bindings/pci/pci-iommu.txt Thanks, Jean
