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/dev-tools/index.rst b/Documentation/dev-tools/index.rst
new file mode 100644
index 000000000..59cbb77b3
--- /dev/null
+++ b/Documentation/dev-tools/index.rst
@@ -0,0 +1,42 @@
+================================
+Development tools for the kernel
+================================
+
+This document is a collection of documents about development tools that can
+be used to work on the kernel. For now, the documents have been pulled
+together without any significant effort to integrate them into a coherent
+whole; patches welcome!
+
+A brief overview of testing-specific tools can be found in
+Documentation/dev-tools/testing-overview.rst
+
+Tools that are specific to debugging can be found in
+Documentation/process/debugging/index.rst
+
+.. toctree::
+   :caption: Table of contents
+   :maxdepth: 2
+
+   testing-overview
+   checkpatch
+   clang-format
+   coccinelle
+   context-analysis
+   sparse
+   kcov
+   gcov
+   kasan
+   kmsan
+   ubsan
+   kmemleak
+   kcsan
+   lkmm/index
+   kfence
+   kselftest
+   kunit/index
+   ktap
+   checkuapi
+   gpio-sloppy-logic-analyzer
+   autofdo
+   propeller
+   container