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, 72 insertions, 0 deletions

diff --git a/drivers/regulator/dummy.c b/drivers/regulator/dummy.c
new file mode 100644
index 000000000..c3e416fd3
--- /dev/null
+++ b/drivers/regulator/dummy.c
@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * dummy.c
+ *
+ * Copyright 2010 Wolfson Microelectronics PLC.
+ *
+ * Author: Mark Brown <broonie@opensource.wolfsonmicro.com>
+ *
+ * This is useful for systems with mixed controllable and
+ * non-controllable regulators, as well as for allowing testing on
+ * systems with no controllable regulators.
+ */
+
+#include <linux/err.h>
+#include <linux/export.h>
+#include <linux/device/faux.h>
+#include <linux/regulator/driver.h>
+#include <linux/regulator/machine.h>
+
+#include "dummy.h"
+
+struct regulator_dev *dummy_regulator_rdev;
+
+static const struct regulator_init_data dummy_initdata = {
+	.constraints = {
+		.always_on = 1,
+	},
+};
+
+static const struct regulator_ops dummy_ops;
+
+static const struct regulator_desc dummy_desc = {
+	.name = "regulator-dummy",
+	.id = -1,
+	.type = REGULATOR_VOLTAGE,
+	.owner = THIS_MODULE,
+	.ops = &dummy_ops,
+};
+
+static int dummy_regulator_probe(struct faux_device *fdev)
+{
+	struct regulator_config config = { };
+	int ret;
+
+	config.dev = &fdev->dev;
+	config.init_data = &dummy_initdata;
+
+	dummy_regulator_rdev = devm_regulator_register(&fdev->dev, &dummy_desc,
+						       &config);
+	if (IS_ERR(dummy_regulator_rdev)) {
+		ret = PTR_ERR(dummy_regulator_rdev);
+		pr_err("Failed to register regulator: %d\n", ret);
+		return ret;
+	}
+
+	return 0;
+}
+
+static struct faux_device_ops dummy_regulator_driver = {
+	.probe = dummy_regulator_probe,
+};
+
+static struct faux_device *dummy_fdev;
+
+void __init regulator_dummy_init(void)
+{
+	dummy_fdev = faux_device_create("reg-dummy", NULL, &dummy_regulator_driver);
+	if (!dummy_fdev) {
+		pr_err("Failed to allocate dummy regulator device\n");
+		return;
+	}
+}