arm64/boot: Disable trapping of PMZR_EL0 writes to EL2grafted

__init_el2_fgt2() writes one mask to both HDFGRTR2_EL2 and HDFGWTR2_EL2.
PMZR_EL0 is write-only, so its trap bit, nPMZR_EL0, exists only in
HDFGWTR2_EL2 and is therefore never set: a PMZR_EL0 write from the host
traps to EL2, where the nVHE hypervisor has no handler and BUG()s. The
kernel never writes PMZR_EL0, but kernel.perf_user_access=1 has the PMU
driver set PMUSERENR_EL0.UEN for a task with a user-read event, so a
write from EL0 reaches the trap and takes the host down without a panic
message.

Accumulate the HDFGWTR2_EL2 bits separately, as __init_el2_fgt() already
does for HDFGWTR_EL2, and set nPMZR_EL0 with the other FEAT_PMUv3p9
bits.

Fixes: 858c7bfcb35e1 ("arm64/boot: Enable EL2 requirements for FEAT_PMUv3p9")
Cc: stable@vger.kernel.org
Signed-off-by: Fuad Tabba <fuad.tabba@linux.dev>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Oliver Upton <oupton@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>

1 files changed, 42 insertions, 0 deletions

diff --git a/Documentation/rust/index.rst b/Documentation/rust/index.rst
new file mode 100644
index 000000000..b78ed0efa
--- /dev/null
+++ b/Documentation/rust/index.rst
@@ -0,0 +1,42 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+Rust
+====
+
+Documentation related to Rust within the kernel. To start using Rust
+in the kernel, please read the quick-start.rst guide.
+
+
+Code documentation
+------------------
+
+Given a kernel configuration, the kernel may generate Rust code documentation,
+i.e. HTML rendered by the ``rustdoc`` tool.
+
+.. only:: rustdoc and html
+
+	This kernel documentation was built with `Rust code documentation
+	<rustdoc/kernel/index.html>`_.
+
+.. only:: not rustdoc and html
+
+	This kernel documentation was not built with Rust code documentation.
+
+A pregenerated version is provided at:
+
+	https://rust.docs.kernel.org
+
+Please see the :ref:`Code documentation <rust_code_documentation>` section for
+more details.
+
+.. toctree::
+    :maxdepth: 1
+
+    quick-start
+    general-information
+    coding-guidelines
+    arch-support
+    testing
+
+You can also find learning materials for Rust in its section in
+:doc:`../process/kernel-docs`.