947051e361
When userspace writes to one of the core registers, we make
sure to narrow the corresponding GPRs if PSTATE indicates
an AArch32 context.
The code tries to check whether the context is EL0 or EL1 so
that it narrows the correct registers. But it does so by checking
the full PSTATE instead of PSTATE.M.
As a consequence, and if we are restoring an AArch32 EL0 context
in a 64bit guest, and that PSTATE has *any* bit set outside of
PSTATE.M, we narrow *all* registers instead of only the first 15,
destroying the 64bit state.
Obviously, this is not something the guest is likely to enjoy.
Correctly masking PSTATE to only evaluate PSTATE.M fixes it.
Fixes: 90c1f934ed71 ("KVM: arm64: Get rid of the AArch32 register mapping code")
Reported-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Cc: stable@vger.kernel.org
Reviewed-by: Nina Schoetterl-Glausch <nsg@linux.ibm.com>
Acked-by: Oliver Upton <oliver.upton@linux.dev>
Link: https://lore.kernel.org/r/20240524141956.1450304-2-maz@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.