RE: [PATCH v8 0/7] KVM PCIe/MSI passthrough on ARM/ARM64: kernel part 3/3: vfio changes

[Yehuda Yitschak <yehuday@marvell.com>]

Tested-by: Yehuda Yitschak <yehuday@marvell.com>

Tested on Armada-7040 using an intel IXGBE (82599ES). 

> -----Original Message-----
> From: linux-arm-kernel [mailto:linux-arm-kernel-
> bounces@lists.infradead.org] On Behalf Of Eric Auger
> Sent: Thursday, April 28, 2016 11:29
> To: eric.auger@st.com; eric.auger@linaro.org; robin.murphy@arm.com;
> alex.williamson@redhat.com; will.deacon@arm.com; joro@8bytes.org;
> tglx@linutronix.de; jason@lakedaemon.net; marc.zyngier@arm.com;
> christoffer.dall@linaro.org; linux-arm-kernel@lists.infradead.org
> Cc: julien.grall@arm.com; patches@linaro.org; Jean-
> Philippe.Brucker@arm.com; p.fedin@samsung.com; linux-
> kernel@vger.kernel.org; Bharat.Bhushan@freescale.com;
> iommu@lists.linux-foundation.org; pranav.sawargaonkar@gmail.com
> Subject: [PATCH v8 0/7] KVM PCIe/MSI passthrough on ARM/ARM64: kernel
> part 3/3: vfio changes
> 
> This series allows the user-space to register a reserved IOVA domain.
> This completes the kernel integration of the whole functionality on top of
> part 1 & 2.
> 
> It also depends on [PATCH 1/3] iommu: Add MMIO mapping type series,
> http://comments.gmane.org/gmane.linux.kernel.iommu/12869
> 
> We reuse the VFIO DMA MAP ioctl with a new flag to bridge to the msi-
> iommu API. The need for provisioning such MSI IOVA range is reported
> through the VFIO_IOMMU_GET_INFO iotcl.
> 
> vfio_iommu_type1 checks if the MSI mapping is safe when attaching the vfio
> group to the container (allow_unsafe_interrupts modality).
> 
> On ARM/ARM64, the IOMMU does not astract IRQ remapping. the modality
> is abstracted on MSI controller side. The GICv3 ITS is the first controller
> advertising the modality.
> 
> More details & context can be found at:
> http://www.linaro.org/blog/core-dump/kvm-pciemsi-passthrough-
> armarm64/
> 
> Best Regards
> 
> Eric
> 
> Testing:
> - functional on ARM64 AMD Overdrive HW (single GICv2m frame) with
>   Intel X540-T2 (SR-IOV capable)
> - Not tested: ARM GICv3 ITS
> 
> References:
> [1] [RFC 0/2] VFIO: Add virtual MSI doorbell support
>     (https://lkml.org/lkml/2015/7/24/135)
> [2] [RFC PATCH 0/6] vfio: Add interface to map MSI pages
>     (https://lists.cs.columbia.edu/pipermail/kvmarm/2015-
> September/016607.html)
> [3] [PATCH v2 0/3] Introduce MSI hardware mapping for VFIO
> 
> (http://permalink.gmane.org/gmane.comp.emulators.kvm.arm.devel/3858)
> 
> Git: complete series available at
> https://git.linaro.org/people/eric.auger/linux.git/shortlog/refs/heads/v4.6-
> rc5-pcie-passthrough-v8
> 
> previous version at
> https://git.linaro.org/people/eric.auger/linux.git/shortlog/refs/heads/v4.6-
> rc4-pcie-passthrough-v7
> 
> QEMU Integration:
> [RFC v2 0/8] KVM PCI/MSI passthrough with mach-virt
> (http://lists.gnu.org/archive/html/qemu-arm/2016-01/msg00444.html)
> https://git.linaro.org/people/eric.auger/qemu.git/shortlog/refs/heads/v2.5.
> 0-pci-passthrough-rfc-v2
> 
> History:
> v7 -> v8:
> - use renamed msi-iommu API
> - VFIO only responsible for setting the IOVA aperture
> - use new DOMAIN_ATTR_MSI_GEOMETRY iommu domain attribute
> 
> v6 -> v7:
> - vfio_find_dma now accepts a dma_type argument.
> - should have recovered the capability to unmap the whole user IOVA range
> - remove computation of nb IOVA pages -> will post a separate RFC for that
>   while respinning the QEMU part
> 
> RFC v5 -> patch v6:
> - split to ease the review process
> 
> RFC v4 -> RFC v5:
> - take into account Thomas' comments on MSI related patches
>   - split "msi: IOMMU map the doorbell address when needed"
>   - increase readability and add comments
>   - fix style issues
>  - split "iommu: Add DOMAIN_ATTR_MSI_MAPPING attribute"
>  - platform ITS now advertises IOMMU_CAP_INTR_REMAP
>  - fix compilation issue with CONFIG_IOMMU API unset
>  - arm-smmu-v3 now advertises DOMAIN_ATTR_MSI_MAPPING
> 
> RFC v3 -> v4:
> - Move doorbell mapping/unmapping in msi.c
> - fix ref count issue on set_affinity: in case of a change in the address
>   the previous address is decremented
> - doorbell map/unmap now is done on msi composition. Should allow the use
>   case for platform MSI controllers
> - create dma-reserved-iommu.h/c exposing/implementing a new API
> dedicated
>   to reserved IOVA management (looking like dma-iommu glue)
> - series reordering to ease the review:
>   - first part is related to IOMMU
>   - second related to MSI sub-system
>   - third related to VFIO (except arm-smmu IOMMU_CAP_INTR_REMAP
> removal)
> - expose the number of requested IOVA pages through
> VFIO_IOMMU_GET_INFO
>   [this partially addresses Marc's comments on
> iommu_get/put_single_reserved
>    size/alignment problematic - which I did not ignore - but I don't know
>    how much I can do at the moment]
> 
> RFC v2 -> RFC v3:
> - should fix wrong handling of some CONFIG combinations:
>   CONFIG_IOVA, CONFIG_IOMMU_API, CONFIG_PCI_MSI_IRQ_DOMAIN
> - fix MSI_FLAG_IRQ_REMAPPING setting in GICv3 ITS (although not tested)
> 
> PATCH v1 -> RFC v2:
> - reverted to RFC since it looks more reasonable ;-) the code is split
>   between VFIO, IOMMU, MSI controller and I am not sure I did the right
>   choices. Also API need to be further discussed.
> - iova API usage in arm-smmu.c.
> - MSI controller natively programs the MSI addr with either the PA or IOVA.
>   This is not done anymore in vfio-pci driver as suggested by Alex.
> - check irq remapping capability of the group
> 
> RFC v1 [2] -> PATCH v1:
> - use the existing dma map/unmap ioctl interface with a flag to register a
>   reserved IOVA range. Use the legacy Rb to store this special vfio_dma.
> - a single reserved IOVA contiguous region now is allowed
> - use of an RB tree indexed by PA to store allocated reserved slots
> - use of a vfio_domain iova_domain to manage iova allocation within the
>   window provided by the userspace
> - vfio alloc_map/unmap_free take a vfio_group handle
> - vfio_group handle is cached in vfio_pci_device
> - add ref counting to bindings
> - user modality enabled at the end of the series
> 
> 
> Eric Auger (7):
>   vfio: introduce a vfio_dma type field
>   vfio/type1: vfio_find_dma accepting a type argument
>   vfio/type1: bypass unmap/unpin and replay for VFIO_IOVA_RESERVED slots
>   vfio: allow reserved msi iova registration
>   vfio/type1: also check IRQ remapping capability at msi domain
>   iommu/arm-smmu: do not advertise IOMMU_CAP_INTR_REMAP
>   vfio/type1: return MSI mapping requirements with
> VFIO_IOMMU_GET_INFO
> 
>  drivers/iommu/arm-smmu-v3.c     |   3 +-
>  drivers/iommu/arm-smmu.c        |   3 +-
>  drivers/vfio/vfio_iommu_type1.c | 227
> +++++++++++++++++++++++++++++++++++++---
>  include/uapi/linux/vfio.h       |  14 ++-
>  4 files changed, 230 insertions(+), 17 deletions(-)
> 
> --
> 1.9.1
> 
> 
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