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When a PASID is used for SVA by a device, it's possible that the PASID
entry is cleared before the device flushes all ongoing DMA requests and
removes the SVA domain. This can occur when an exception happens and the
process terminates before the device driver stops DMA and calls the
iommu driver to unbind the PASID.
There's no need to drain the PRQ in the mm release path. Instead, the PRQ
will be drained in the SVA unbind path.
Unfortunately, commit c43e1ccdebf2 ("iommu/vt-d: Drain PRQs when domain
removed from RID") changed this behavior by unconditionally draining the
PRQ in intel_pasid_tear_down_entry(). This can lead to a potential
sleeping-in-atomic-context issue.
Smatch static checker warning:
drivers/iommu/intel/prq.c:95 intel_iommu_drain_pasid_prq()
warn: sleeping in atomic context
To avoid this issue, prevent draining the PRQ in the SVA mm release path
and restore the previous behavior.
Fixes: c43e1ccdebf2 ("iommu/vt-d: Drain PRQs when domain removed from RID")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/linux-iommu/c5187676-2fa2-4e29-94e0-4a279dc88b49@stanley.mountain/
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20241212021529.1104745-1-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.