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On the pseries machine the IOMMU (aka TCE tables) is always active for all
PCI and VIO devices. Mostly to simplify the SLOF firmware, we implement an
extension which allows the IOMMU to be temporarily disabled for certain
devices.
Currently this is implemented by setting the device's DMAContext pointer to
NULL (thus reverting to qemu's default no-IOMMU DMA behaviour), then
replacing it when bypass mode is disabled.
This approach causes a bunch of complications though. It complexifies the
management of the DMAContext lifetimes, it's problematic for savevm/loadvm,
and it means that while bypass is active we have nowhere to store the
device's LIOBN (Logical IO Bus Number, used to identify DMA address
spaces). At present we regenerate the LIOBN from other address information
but this restricts how we can allocate LIOBNs.
This patch gives up on this approach, replacing it with the much simpler
one of having a 'bypass' boolean flag in the TCE state structure.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Alexander Graf <agraf@suse.de>
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The emulated PCI host bridge on the pseries machine incorporates an IOMMU
(PAPR TCE table). Currently the mappings in this IOMMU are not cleared
when we reset the system. This patch fixes this bug. To do this it adds
a new reset function to the IOMMU emulation code. The VIO devices already
reset their TCE tables, but they do so by destroying and re-creating their
DMA context. This doesn't work for the PCI host bridge, because the
infrastructure for PCI IOMMUs has already copied/cached the DMA pointer
context into the subordinate PCI device structures.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Alexander Graf <agraf@suse.de>
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Previously the only PCI bus supported was the emulated PCI bus with
fixed DMA window with start at 0 and size 1GB. As we are going to support
PCI pass through which DMA window properties are set by the host
kernel, we have to support DMA windows with parameters other than default.
This patch adds:
1. DMA window properties to sPAPRPHBState: LIOBN (bus id), start,
size of the window.
2. An additional function spapr_dma_dt() to populate DMA window
properties in the device tree which simply accepts all the parameters
and does not try to guess what kind of IOMMU is given to it.
The original spapr_dma_dt() is renamed to spapr_tcet_dma_dt().
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Alexander Graf <agraf@suse.de>
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Currently the pseries machine emulation does not support DMA for emulated
PCI devices, because the PAPR spec always requires a (guest visible,
paravirtualized) IOMMU which was not implemented. Now that we have
infrastructure for IOMMU emulation, we can correct this and allow PCI DMA
for pseries.
With the existing PAPR IOMMU code used for VIO devices, this is almost
trivial. We use a single DMAContext for each (virtual) PCI host bridge,
which is the usual configuration on real PAPR machines (which often have
_many_ PCI host bridges).
Cc: Alex Graf <agraf@suse.de>
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
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The pseries platform already contains an IOMMU implementation, since it is
essential for the platform's paravirtualized VIO devices. This IOMMU
support is currently built into the implementation of the VIO "bus" and
the various VIO devices.
This patch converts this code to make use of the new common IOMMU
infrastructure.
We don't yet handle synchronization of map/unmap callbacks vs. invalidations,
this will require some complex interaction with the kernel and is not a
major concern at this stage.
Cc: Alex Graf <agraf@suse.de>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
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