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Zenghui reports that running a KVM guest with an assigned device and
lockdep enabled produces an unfriendly splat due to an inconsistent irq
context when taking the lpi_xa's spinlock.
This is no good as in rare cases the last reference to an LPI can get
dropped after injection of a cached LPI translation. In this case,
vgic_put_irq() will release the IRQ struct and take the lpi_xa's
spinlock to erase it from the xarray.
Reinstate the IRQ ordering and update the lockdep hint accordingly. Note
that there is no irqsave equivalent of might_lock(), so just explictly
grab and release the spinlock on lockdep kernels.
Reported-by: Zenghui Yu <yuzenghui@huawei.com>
Closes: https://lore.kernel.org/kvmarm/b4d7cb0f-f007-0b81-46d1-998b15cc14bc@huawei.com/
Fixes: 982f31bbb5 ("KVM: arm64: vgic-v3: Don't require IRQs be disabled for LPI xarray lock")
Signed-off-by: Oliver Upton <oupton@kernel.org>
Link: https://patch.msgid.link/20251107184847.1784820-2-oupton@kernel.org
Signed-off-by: Marc Zyngier <maz@kernel.org>
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.