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, 70 insertions, 0 deletions

diff --git a/drivers/base/regmap/regmap-slimbus.c b/drivers/base/regmap/regmap-slimbus.c
new file mode 100644
index 000000000..e523fae73
--- /dev/null
+++ b/drivers/base/regmap/regmap-slimbus.c
@@ -0,0 +1,70 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2017, Linaro Ltd.
+
+#include <linux/regmap.h>
+#include <linux/slimbus.h>
+#include <linux/module.h>
+
+#include "internal.h"
+
+static int regmap_slimbus_write(void *context, const void *data, size_t count)
+{
+	struct slim_device *sdev = context;
+
+	return slim_write(sdev, *(u16 *)data, count - 2, (u8 *)data + 2);
+}
+
+static int regmap_slimbus_read(void *context, const void *reg, size_t reg_size,
+			       void *val, size_t val_size)
+{
+	struct slim_device *sdev = context;
+
+	return slim_read(sdev, *(u16 *)reg, val_size, val);
+}
+
+static const struct regmap_bus regmap_slimbus_bus = {
+	.write = regmap_slimbus_write,
+	.read = regmap_slimbus_read,
+	.reg_format_endian_default = REGMAP_ENDIAN_LITTLE,
+	.val_format_endian_default = REGMAP_ENDIAN_LITTLE,
+};
+
+static const struct regmap_bus *regmap_get_slimbus(struct slim_device *slim,
+					const struct regmap_config *config)
+{
+	if (config->val_bits == 8 && config->reg_bits == 16)
+		return &regmap_slimbus_bus;
+
+	return ERR_PTR(-ENOTSUPP);
+}
+
+struct regmap *__regmap_init_slimbus(struct slim_device *slimbus,
+				     const struct regmap_config *config,
+				     struct lock_class_key *lock_key,
+				     const char *lock_name)
+{
+	const struct regmap_bus *bus = regmap_get_slimbus(slimbus, config);
+
+	if (IS_ERR(bus))
+		return ERR_CAST(bus);
+
+	return __regmap_init(&slimbus->dev, bus, slimbus, config, lock_key, lock_name);
+}
+EXPORT_SYMBOL_GPL(__regmap_init_slimbus);
+
+struct regmap *__devm_regmap_init_slimbus(struct slim_device *slimbus,
+					  const struct regmap_config *config,
+					  struct lock_class_key *lock_key,
+					  const char *lock_name)
+{
+	const struct regmap_bus *bus = regmap_get_slimbus(slimbus, config);
+
+	if (IS_ERR(bus))
+		return ERR_CAST(bus);
+
+	return __devm_regmap_init(&slimbus->dev, bus, slimbus, config, lock_key, lock_name);
+}
+EXPORT_SYMBOL_GPL(__devm_regmap_init_slimbus);
+
+MODULE_DESCRIPTION("Register map access API - SLIMbus support");
+MODULE_LICENSE("GPL v2");