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habanalabs: Allow accessing host mapped addresses via debugfs

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Allows using the addr/data32 debugfs nodes to access a device VA of a
host mapped memory when the IOMMU is disabled.

Due to the possible large amount of a user host mapped memory, the
driver doesn't maintain a database with the host addresses per device VA.
When the IOMMU is disabled, this missing info is being overcome by
simply using phys_to_virt(). However, this is not useful when the IOMMU
is enabled, and thus the enforced limitation.

Signed-off-by: Tomer Tayar <ttayar@habana.ai>
Reviewed-by: Oded Gabbay <oded.gabbay@gmail.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>
This commit is contained in:
Tomer Tayar
2019-06-16 13:48:29 +00:00
committed by Oded Gabbay
parent 747bf88c61
commit 4a0ce7764b
3 changed files with 46 additions and 19 deletions
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11
Documentation/ABI/testing/debugfs-driver-habanalabs
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@@ -3,7 +3,10 @@ Date: Jan 2019
KernelVersion: 5.1
Contact: oded.gabbay@gmail.com
Description: Sets the device address to be used for read or write through
PCI bar. The acceptable value is a string that starts with "0x"
PCI bar, or the device VA of a host mapped memory to be read or
written directly from the host. The latter option is allowed
only when the IOMMU is disabled.
The acceptable value is a string that starts with "0x"
What: /sys/kernel/debug/habanalabs/hl<n>/command_buffers
Date: Jan 2019
@@ -33,10 +36,12 @@ Contact: oded.gabbay@gmail.com
Description: Allows the root user to read or write directly through the
device's PCI bar. Writing to this file generates a write
transaction while reading from the file generates a read
transcation. This custom interface is needed (instead of using
transaction. This custom interface is needed (instead of using
the generic Linux user-space PCI mapping) because the DDR bar
is very small compared to the DDR memory and only the driver can
move the bar before and after the transaction
move the bar before and after the transaction.
If the IOMMU is disabled, it also allows the root user to read
or write from the host a device VA of a host mapped memory
What: /sys/kernel/debug/habanalabs/hl<n>/device
Date: Jan 2019