From fe9a344c5be3e4a87429fe76775f6efcd8cc4092 Mon Sep 17 00:00:00 2001 From: Michal Krawczyk Date: Wed, 8 Apr 2020 10:29:20 +0200 Subject: [PATCH] doc: add notes on ENA usage on metal instances As AWS metal instances are supporting IOMMU, the usage of igb_uio or vfio-pci can lead to a problems (when to use which module), especially that the vfio-pci isn't supporting SMMU on arm64. To clear up the problem of using those modules in various setup conditions (with or without IOMMU) on metal instances, more detailed explanation was added. Signed-off-by: Michal Krawczyk Reviewed-by: Igor Chauskin Reviewed-by: Guy Tzalik --- doc/guides/nics/ena.rst | 48 +++++++++++++++++++++++++++++++++++++++-- 1 file changed, 46 insertions(+), 2 deletions(-) diff --git a/doc/guides/nics/ena.rst b/doc/guides/nics/ena.rst index 0b9622ac85..bec97c3326 100644 --- a/doc/guides/nics/ena.rst +++ b/doc/guides/nics/ena.rst @@ -187,11 +187,55 @@ Prerequisites echo 1 > /sys/module/vfio/parameters/enable_unsafe_noiommu_mode -#. Bind the intended ENA device to ``vfio-pci`` or ``igb_uio`` module. + To use ``noiommu`` mode, the ``vfio-pci`` must be built with flag + ``CONFIG_VFIO_NOIOMMU``. +#. Bind the intended ENA device to ``vfio-pci`` or ``igb_uio`` module. At this point the system should be ready to run DPDK applications. Once the -application runs to completion, the ENA can be detached from igb_uio if necessary. +application runs to completion, the ENA can be detached from attached module if +necessary. + +**Note about usage on \*.metal instances** + +On AWS, the metal instances are supporting IOMMU for both arm64 and x86_64 +hosts. + +* x86_64 (e.g. c5.metal, i3.metal): + IOMMU should be disabled by default. In that situation, the ``igb_uio`` can + be used as it is but ``vfio-pci`` should be working in no-IOMMU mode (please + see above). + + When IOMMU is enabled, ``igb_uio`` cannot be used as it's not supporting this + feature, while ``vfio-pci`` should work without any changes. + To enable IOMMU on those hosts, please update ``GRUB_CMDLINE_LINUX`` in file + ``/etc/default/grub`` with the below extra boot arguments:: + + iommu=1 intel_iommu=on + + Then, make the changes live by executing as a root:: + + # grub2-mkconfig > /boot/grub2/grub.cfg + + Finally, reboot should result in IOMMU being enabled. + +* arm64 (a1.metal): + IOMMU should be enabled by default. Unfortunately, ``vfio-pci`` isn't + supporting SMMU, which is implementation of IOMMU for arm64 architecture and + ``igb_uio`` isn't supporting IOMMU at all, so to use DPDK with ENA on those + hosts, one must disable IOMMU. This can be done by updating + ``GRUB_CMDLINE_LINUX`` in file ``/etc/default/grub`` with the extra boot + argument:: + + iommu.passthrough=1 + + Then, make the changes live by executing as a root:: + + # grub2-mkconfig > /boot/grub2/grub.cfg + + Finally, reboot should result in IOMMU being disabled. + Without IOMMU, ``igb_uio`` can be used as it is but ``vfio-pci`` should be + working in no-IOMMU mode (please see above). Usage example ------------- -- 2.20.1