On 14/10/2016 13:24, Punit Agrawal wrote:
> Hi Eric,
> I am a bit late in joining, but I've tried to familiarise
> myself with earlier discussions on the series.
> Eric Auger <eric.au...@redhat.com> writes:
>> This is the second respin on top of Robin's series , addressing Alex'
>> Major changes are:
>> - MSI-doorbell API now is moved to DMA IOMMU API following Alex suggestion
>> to put all API pieces at the same place (so eventually in the IOMMU
> IMHO, this is headed in the opposite direction, i.e., away from the
> owner of the information - the doorbells are the property of the MSI
> controller. The MSI controllers know the location, size and interrupt
> remapping capability as well. On the consumer side, VFIO needs access to
> the doorbells to allow userspace to carve out a region in the IOVA.
> I quite liked what you had in v13, though I think you can go further
> though. Instead of adding new doorbell API [un]registration calls, how
> about adding a callback to the irq_domain_ops? The callback will be
> populated for irqdomains registered by MSI controllers.
Thank you for jumping into that thread. Any help/feedback is greatly
Regarding your suggestion, the irq_domain looks dedicated to the
translation between linux irq and HW irq. I tend to think adding an ops
to retrieve the MSI doorbell info at that level looks far from the
original goal of the infrastructure. Obviously the fact there is a list
of such domain is tempting but I preferred to add a separate struct and
In the v14 release I moved the "doorbell API" in the dma-iommu API since
Alex recommended to offer a unified API where all pieces would be at the
Anyway I will follow the guidance of maintainers.
> From VFIO, we can calculate the required aperture reservation by
> iterating over the irqdomains (something like irq_domain_for_each). The
> same callback can also provide information about support for interrupt
> For systems where there are no separate MSI controllers, i.e., the IOMMU
> has a fixed reservation, no MSI callbacks will be populated - which
> tells userspace that no separate MSI reservation is required. IIUC, this
> was one of Alex' concerns on the prior version.
I'am working on a separate series to report to the user-space the usable
> Thoughts, opinions?
>> - new iommu_domain_msi_resv struct and accessor through DOMAIN_ATTR_MSI_RESV
>> domain with mirror VFIO capability
>> - more robustness I think in the VFIO layer
>> - added "iommu/iova: fix __alloc_and_insert_iova_range" since with the
>> code I failed allocating an IOVA page in a single page domain with upper
>> IOVA range exclusion will be handled in a separate series
>> The priority really is to discuss and freeze the API and especially the MSI
>> doorbell's handling. Do we agree to put that in DMA IOMMU?
>> Note: the size computation does not take into account possible page overlaps
>> between doorbells but it would add quite a lot of complexity i think.
>> Tested on AMD Overdrive (single GICv2m frame) with I350 VF assignment.
>> the series depends on Robin's generic-v7 branch:
>>  [PATCH v7 00/22] Generic DT bindings for PCI IOMMUs and ARM SMMU
>> Best Regards
>> Git: complete series available at
>> the above branch includes a temporary patch to work around a ThunderX pci
>> bus reset crash (which I think unrelated to this series):
>> "vfio: pci: HACK! workaround thunderx pci_try_reset_bus crash"
>> Do not take this one for other platforms.
>> Eric Auger (15):
>> iommu/iova: fix __alloc_and_insert_iova_range
>> iommu: Introduce DOMAIN_ATTR_MSI_RESV
>> iommu/dma: MSI doorbell alloc/free
>> iommu/dma: Introduce iommu_calc_msi_resv
>> iommu/arm-smmu: Implement domain_get_attr for DOMAIN_ATTR_MSI_RESV
>> irqchip/gic-v2m: Register the MSI doorbell
>> irqchip/gicv3-its: Register the MSI doorbell
>> vfio: Introduce a vfio_dma type field
>> vfio/type1: vfio_find_dma accepting a type argument
>> vfio/type1: Implement recursive vfio_find_dma_from_node
>> vfio/type1: Handle unmap/unpin and replay for VFIO_IOVA_RESERVED slots
>> vfio: Allow reserved msi iova registration
>> vfio/type1: Check doorbell safety
>> iommu/arm-smmu: Do not advertise IOMMU_CAP_INTR_REMAP
>> vfio/type1: Introduce MSI_RESV capability
>> Robin Murphy (1):
>> iommu/dma: Allow MSI-only cookies
>> drivers/iommu/Kconfig | 4 +-
>> drivers/iommu/arm-smmu-v3.c | 10 +-
>> drivers/iommu/arm-smmu.c | 10 +-
>> drivers/iommu/dma-iommu.c | 184 ++++++++++++++++++++++++++
>> drivers/iommu/iova.c | 2 +-
>> drivers/irqchip/irq-gic-v2m.c | 10 +-
>> drivers/irqchip/irq-gic-v3-its.c | 13 ++
>> drivers/vfio/vfio_iommu_type1.c | 279
>> include/linux/dma-iommu.h | 59 +++++++++
>> include/linux/iommu.h | 8 ++
>> include/uapi/linux/vfio.h | 30 ++++-
>> 11 files changed, 587 insertions(+), 22 deletions(-)
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