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, 78 insertions, 0 deletions

diff --git a/Documentation/networking/ipv6.rst b/Documentation/networking/ipv6.rst
new file mode 100644
index 000000000..ba09c2f2d
--- /dev/null
+++ b/Documentation/networking/ipv6.rst
@@ -0,0 +1,78 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+====
+IPv6
+====
+
+
+Options for the ipv6 module are supplied as parameters at load time.
+
+Module options may be given as command line arguments to the insmod
+or modprobe command, but are usually specified in either
+``/etc/modules.d/*.conf`` configuration files, or in a distro-specific
+configuration file.
+
+The available ipv6 module parameters are listed below.  If a parameter
+is not specified the default value is used.
+
+The parameters are as follows:
+
+disable
+
+	Specifies whether to load the IPv6 module, but disable all
+	its functionality.  This might be used when another module
+	has a dependency on the IPv6 module being loaded, but no
+	IPv6 addresses or operations are desired.
+
+	The possible values and their effects are:
+
+	0
+		IPv6 is enabled.
+
+		This is the default value.
+
+	1
+		IPv6 is disabled.
+
+		No IPv6 addresses will be added to interfaces, and
+		it will not be possible to open an IPv6 socket.
+
+		A reboot is required to enable IPv6.
+
+autoconf
+
+	Specifies whether to enable IPv6 address autoconfiguration
+	on all interfaces.  This might be used when one does not wish
+	for addresses to be automatically generated from prefixes
+	received in Router Advertisements.
+
+	The possible values and their effects are:
+
+	0
+		IPv6 address autoconfiguration is disabled on all interfaces.
+
+		Only the IPv6 loopback address (::1) and link-local addresses
+		will be added to interfaces.
+
+	1
+		IPv6 address autoconfiguration is enabled on all interfaces.
+
+		This is the default value.
+
+disable_ipv6
+
+	Specifies whether to disable IPv6 on all interfaces.
+	This might be used when no IPv6 addresses are desired.
+
+	The possible values and their effects are:
+
+	0
+		IPv6 is enabled on all interfaces.
+
+		This is the default value.
+
+	1
+		IPv6 is disabled on all interfaces.
+
+		No IPv6 addresses will be added to interfaces.
+