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In hindsight, there were some crucial subtleties overlooked when moving
{of,acpi}_dma_configure() to driver probe time to allow waiting for
IOMMU drivers with -EPROBE_DEFER, and these have become an
ever-increasing source of problems. The IOMMU API has some fundamental
assumptions that iommu_probe_device() is called for every device added
to the system, in the order in which they are added. Calling it in a
random order or not at all dependent on driver binding leads to
malformed groups, a potential lack of isolation for devices with no
driver, and all manner of unexpected concurrency and race conditions.
We've attempted to mitigate the latter with point-fix bodges like
iommu_probe_device_lock, but it's a losing battle and the time has come
to bite the bullet and address the true source of the problem instead.
The crux of the matter is that the firmware parsing actually serves two
distinct purposes; one is identifying the IOMMU instance associated with
a device so we can check its availability, the second is actually
telling that instance about the relevant firmware-provided data for the
device. However the latter also depends on the former, and at the time
there was no good place to defer and retry that separately from the
availability check we also wanted for client driver probe.
Nowadays, though, we have a proper notion of multiple IOMMU instances in
the core API itself, and each one gets a chance to probe its own devices
upon registration, so we can finally make that work as intended for
DT/IORT/VIOT platforms too. All we need is for iommu_probe_device() to
be able to run the iommu_fwspec machinery currently buried deep in the
wrong end of {of,acpi}_dma_configure(). Luckily it turns out to be
surprisingly straightforward to bootstrap this transformation by pretty
much just calling the same path twice. At client driver probe time,
dev->driver is obviously set; conversely at device_add(), or a
subsequent bus_iommu_probe(), any device waiting for an IOMMU really
should *not* have a driver already, so we can use that as a condition to
disambiguate the two cases, and avoid recursing back into the IOMMU core
at the wrong times.
Obviously this isn't the nicest thing, but for now it gives us a
functional baseline to then unpick the layers in between without many
more awkward cross-subsystem patches. There are some minor side-effects
like dma_range_map potentially being created earlier, and some debug
prints being repeated, but these aren't significantly detrimental. Let's
make things work first, then deal with making them nice.
With the basic flow finally in the right order again, the next step is
probably turning the bus->dma_configure paths inside-out, since all we
really need from bus code is its notion of which device and input ID(s)
to parse the common firmware properties with...
Acked-by: Bjorn Helgaas <bhelgaas@google.com> # pci-driver.c
Acked-by: Rob Herring (Arm) <robh@kernel.org> # of/device.c
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Reviewed-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/e3b191e6fd6ca9a1e84c5e5e40044faf97abb874.1740753261.git.robin.murphy@arm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
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Several places want to compute the lower and/or upper bounds of a
dma_range_map, so let's factor that out into reusable helpers.
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hanjun Guo <guohanjun@huawei.com> # For arm64
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Tested-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/45ec52f033ec4dfb364e23f48abaf787f612fa53.1713523152.git.robin.murphy@arm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
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Return the Root Complex/Named Component memory address size limit as an
inclusive limit value, rather than an exclusive size. This saves having
to fudge an off-by-one for the 64-bit case, and simplifies our caller.
Acked-by: Hanjun Guo <guohanjun@huawei.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Tested-by: Hanjun Guo <guohanjun@huawei.com>
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/284ae9fbadb12f2e3b5a30cd4d037d0e6843a8f4.1713523152.git.robin.murphy@arm.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
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In DT systems configurations, of_dma_get_range() returns struct
bus_dma_region DMA regions; they are used to set-up devices
DMA windows with different offset available for translation between DMA
address and CPU address.
In ACPI systems configuration, acpi_dma_get_range() does not return
DMA regions yet and that precludes setting up the dev->dma_range_map
pointer and therefore DMA regions with multiple offsets.
Update acpi_dma_get_range() to return struct bus_dma_region
DMA regions like of_dma_get_range() does.
After updating acpi_dma_get_range(), acpi_arch_dma_setup() is changed for
ARM64, where the original dma_addr and size are removed as these
arguments are now redundant, and pass 0 and U64_MAX for dma_base
and size of arch_setup_dma_ops; this is a simplification consistent
with what other ACPI architectures also pass to iommu_setup_dma_ops().
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Jianmin Lv <lvjianmin@loongson.cn>
Reviewed-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
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Extract generic DMA setup code out of IORT, so it can be reused by VIOT.
Keep it in drivers/acpi/arm64 for now, since it could break x86
platforms that haven't run this code so far, if they have invalid
tables.
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
Link: https://lore.kernel.org/r/20210618152059.1194210-2-jean-philippe@linaro.org
Signed-off-by: Joerg Roedel <jroedel@suse.de>
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