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, 52 insertions, 0 deletions

diff --git a/Documentation/driver-api/target.rst b/Documentation/driver-api/target.rst
new file mode 100644
index 000000000..c70ca2517
--- /dev/null
+++ b/Documentation/driver-api/target.rst
@@ -0,0 +1,52 @@
+=================================
+target and iSCSI Interfaces Guide
+=================================
+
+Introduction and Overview
+=========================
+
+TBD
+
+Target core device interfaces
+=============================
+
+This section is blank because no kerneldoc comments have been added to
+drivers/target/target_core_device.c.
+
+Target core transport interfaces
+================================
+
+.. kernel-doc:: drivers/target/target_core_transport.c
+    :export:
+
+Target-supported userspace I/O
+==============================
+
+.. kernel-doc:: drivers/target/target_core_user.c
+    :doc: Userspace I/O
+
+.. kernel-doc:: include/uapi/linux/target_core_user.h
+    :doc: Ring Design
+
+iSCSI helper functions
+======================
+
+.. kernel-doc:: drivers/scsi/libiscsi.c
+   :export:
+
+
+iSCSI boot information
+======================
+
+.. kernel-doc:: drivers/scsi/iscsi_boot_sysfs.c
+   :export:
+
+iSCSI TCP interfaces
+====================
+
+.. kernel-doc:: drivers/scsi/iscsi_tcp.c
+   :internal:
+
+.. kernel-doc:: drivers/scsi/libiscsi_tcp.c
+   :export:
+