[RFC v4 00/16] KVM PCIe/MSI passthrough on ARM/ARM64 and IOVA reserved regions

From: Eric Auger
Date: Tue Dec 13 2016 - 15:41:09 EST

Following LPC discussions, we now report reserved regions through
iommu-group sysfs reserved_regions attribute file.

Reserved regions are populated through the IOMMU get_resv_region
callback (former get_dm_regions), now implemented by amd-iommu,
intel-iommu and arm-smmu:
- the amd-iommu reports device direct mapped regions.
- the intel-iommu reports the [0xfee00000 - 0xfeefffff] MSI window
as an IOMMU_RESV_NOMAP reserved region.
- the arm-smmu reports the MSI window (arbitrarily located at
0x8000000 and 1MB large).

Unsafe interrupt assignment is tested by enumerating all MSI irq
domains and checking they support MSI remapping. This check is done
in case we detect the iommu translates MSI (an IOMMU_RESV_MSI
window exists). Otherwise the IRQ remapping capability is checked
at IOMMU level. Obviously this is a defensive IRQ safety assessment.
Assuming there are several MSI controllers in the system and at
least one does not implement IRQ remapping, the assignment will be
considered as unsafe (even if this controller is not acessible from
the assigned devices).

The series integrates a not officially posted patch from Robin:
"iommu/dma: Allow MSI-only cookies".

Best Regards


Git: complete series available at


RFCv3 -> RFCv4:
- arm-smmu driver does not register PCI host bridge windows as
reserved regions anymore
- Implement reserved region get/put callbacks also in arm-smmuv3
- take the iommu_group lock on iommu_get_group_resv_regions
- add a type field in iommu_resv_region instead of using prot
- init the region list_head in iommu_alloc_resv_region, also
add type parameter
- iommu_insert_resv_region manage overlaps and sort reserved
- address IRQ safety assessment by enumerating all the MSI irq
domains and checking the MSI_REMAP flag
- update Documentation/ABI/testing/sysfs-kernel-iommu_groups
- Did not add T-b since the code has significantly changed

RFCv2 -> RFCv3:
- switch to an iommu-group sysfs API
- use new dummy allocator provided by Robin
- dummy allocator initialized by vfio-iommu-type1 after enumerating
the reserved regions
- at the moment ARM MSI base address/size is left unchanged compared
to v2
- we currently report reserved regions and not usable IOVA regions as
requested by Alex

RFC v1 -> v2:
- fix intel_add_reserved_regions
- add mutex lock/unlock in vfio_iommu_type1

Eric Auger (16):
iommu/dma: Allow MSI-only cookies
iommu: Rename iommu_dm_regions into iommu_resv_regions
iommu: Add a new type field in iommu_resv_region
iommu: iommu_alloc_resv_region
iommu: Only map direct mapped regions
iommu: iommu_get_group_resv_regions
iommu: Implement reserved_regions iommu-group sysfs file
iommu/vt-d: Implement reserved region get/put callbacks
iommu/arm-smmu: Implement reserved region get/put callbacks
iommu/arm-smmu-v3: Implement reserved region get/put callbacks
irqdomain: Add IRQ_DOMAIN_FLAG_MSI_REMAP value
irqdomain: irq_domain_check_msi_remap
irqchip/gicv3-its: Sets IRQ_DOMAIN_FLAG_MSI_REMAP
vfio/type1: Allow transparent MSI IOVA allocation
vfio/type1: Check MSI remapping at irq domain level
iommu/arm-smmu: Do not advertise IOMMU_CAP_INTR_REMAP anymore

.../ABI/testing/sysfs-kernel-iommu_groups | 9 ++
drivers/iommu/amd_iommu.c | 21 +--
drivers/iommu/arm-smmu-v3.c | 30 +++-
drivers/iommu/arm-smmu.c | 30 +++-
drivers/iommu/dma-iommu.c | 116 +++++++++++++---
drivers/iommu/intel-iommu.c | 50 +++++--
drivers/iommu/iommu.c | 152 +++++++++++++++++++--
drivers/irqchip/irq-gic-v3-its.c | 1 +
drivers/vfio/vfio_iommu_type1.c | 37 ++++-
include/linux/dma-iommu.h | 7 +
include/linux/iommu.h | 46 +++++--
include/linux/irqdomain.h | 8 ++
kernel/irq/irqdomain.c | 24 ++++
13 files changed, 455 insertions(+), 76 deletions(-)