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, 63 insertions, 0 deletions

diff --git a/drivers/regulator/fixed-helper.c b/drivers/regulator/fixed-helper.c
new file mode 100644
index 000000000..ba5551ac0
--- /dev/null
+++ b/drivers/regulator/fixed-helper.c
@@ -0,0 +1,63 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/machine.h>
+#include <linux/regulator/fixed.h>
+
+struct fixed_regulator_data {
+	struct fixed_voltage_config cfg;
+	struct regulator_init_data init_data;
+	struct platform_device pdev;
+};
+
+static void regulator_fixed_release(struct device *dev)
+{
+	struct fixed_regulator_data *data = container_of(dev,
+			struct fixed_regulator_data, pdev.dev);
+	kfree_const(data->cfg.supply_name);
+	kfree(data);
+}
+
+/**
+ * regulator_register_always_on - register an always-on regulator with a fixed name
+ * @id: platform device id
+ * @name: name to be used for the regulator
+ * @supplies: consumers for this regulator
+ * @num_supplies: number of consumers
+ * @uv: voltage in microvolts
+ *
+ * Return: Pointer to registered platform device, or %NULL if memory allocation fails.
+ */
+struct platform_device *regulator_register_always_on(int id, const char *name,
+	struct regulator_consumer_supply *supplies, int num_supplies, int uv)
+{
+	struct fixed_regulator_data *data;
+
+	data = kzalloc_obj(*data);
+	if (!data)
+		return NULL;
+
+	data->cfg.supply_name = kstrdup_const(name, GFP_KERNEL);
+	if (!data->cfg.supply_name) {
+		kfree(data);
+		return NULL;
+	}
+
+	data->cfg.microvolts = uv;
+	data->cfg.enabled_at_boot = 1;
+	data->cfg.init_data = &data->init_data;
+
+	data->init_data.constraints.always_on = 1;
+	data->init_data.consumer_supplies = supplies;
+	data->init_data.num_consumer_supplies = num_supplies;
+
+	data->pdev.name = "reg-fixed-voltage";
+	data->pdev.id = id;
+	data->pdev.dev.platform_data = &data->cfg;
+	data->pdev.dev.release = regulator_fixed_release;
+
+	platform_device_register(&data->pdev);
+
+	return &data->pdev;
+}