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, 160 insertions, 0 deletions

diff --git a/drivers/power/reset/syscon-reboot.c b/drivers/power/reset/syscon-reboot.c
new file mode 100644
index 000000000..60e855cae
--- /dev/null
+++ b/drivers/power/reset/syscon-reboot.c
@@ -0,0 +1,160 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Generic Syscon Reboot Driver
+ *
+ * Copyright (c) 2013, Applied Micro Circuits Corporation
+ * Author: Feng Kan <fkan@apm.com>
+ */
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/notifier.h>
+#include <linux/mfd/syscon.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reboot.h>
+#include <linux/regmap.h>
+
+struct reboot_mode_bits {
+	u32 offset;
+	u32 mask;
+	u32 value;
+	bool valid;
+};
+
+struct reboot_data {
+	struct reboot_mode_bits mode_bits[REBOOT_SOFT + 1];
+	struct reboot_mode_bits catchall;
+};
+
+struct syscon_reboot_context {
+	struct regmap *map;
+
+	const struct reboot_data *rd; /* from of match data, if any */
+	struct reboot_mode_bits catchall; /* from DT */
+
+	struct notifier_block restart_handler;
+};
+
+static int syscon_restart_handle(struct notifier_block *this,
+					unsigned long mode, void *cmd)
+{
+	struct syscon_reboot_context *ctx =
+			container_of(this, struct syscon_reboot_context,
+					restart_handler);
+	const struct reboot_mode_bits *mode_bits;
+
+	if (ctx->rd) {
+		if (mode < ARRAY_SIZE(ctx->rd->mode_bits) &&
+		    ctx->rd->mode_bits[mode].valid)
+			mode_bits = &ctx->rd->mode_bits[mode];
+		else
+			mode_bits = &ctx->rd->catchall;
+	} else {
+		mode_bits = &ctx->catchall;
+	}
+
+	/* Issue the reboot */
+	regmap_update_bits(ctx->map, mode_bits->offset, mode_bits->mask,
+			   mode_bits->value);
+
+	mdelay(1000);
+
+	pr_emerg("Unable to restart system\n");
+	return NOTIFY_DONE;
+}
+
+static int syscon_reboot_probe(struct platform_device *pdev)
+{
+	struct syscon_reboot_context *ctx;
+	struct device *dev = &pdev->dev;
+	u32 priority;
+	int err;
+
+	ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
+	if (!ctx)
+		return -ENOMEM;
+
+	ctx->map = syscon_regmap_lookup_by_phandle(dev->of_node, "regmap");
+	if (IS_ERR(ctx->map)) {
+		ctx->map = syscon_node_to_regmap(dev->parent->of_node);
+		if (IS_ERR(ctx->map))
+			return PTR_ERR(ctx->map);
+	}
+
+	if (of_property_read_u32(pdev->dev.of_node, "priority", &priority))
+		priority = 192;
+
+	ctx->rd = of_device_get_match_data(dev);
+	if (!ctx->rd) {
+		int mask_err, value_err;
+
+		if (of_property_read_u32(pdev->dev.of_node, "offset",
+					 &ctx->catchall.offset) &&
+		    of_property_read_u32(pdev->dev.of_node, "reg",
+					 &ctx->catchall.offset))
+			return -EINVAL;
+
+		value_err = of_property_read_u32(pdev->dev.of_node, "value",
+						 &ctx->catchall.value);
+		mask_err = of_property_read_u32(pdev->dev.of_node, "mask",
+						&ctx->catchall.mask);
+		if (value_err && mask_err) {
+			dev_err(dev, "unable to read 'value' and 'mask'");
+			return -EINVAL;
+		}
+
+		if (value_err) {
+			/* support old binding */
+			ctx->catchall.value = ctx->catchall.mask;
+			ctx->catchall.mask = 0xFFFFFFFF;
+		} else if (mask_err) {
+			/* support value without mask */
+			ctx->catchall.mask = 0xFFFFFFFF;
+		}
+	}
+
+	ctx->restart_handler.notifier_call = syscon_restart_handle;
+	ctx->restart_handler.priority = priority;
+	err = register_restart_handler(&ctx->restart_handler);
+	if (err)
+		dev_err(dev, "can't register restart notifier (err=%d)\n", err);
+
+	return err;
+}
+
+static const struct reboot_data gs101_reboot_data = {
+	.mode_bits = {
+		[REBOOT_WARM] = {
+			.offset = 0x3a00, /* SYSTEM_CONFIGURATION */
+			.mask = 0x00000002, /* SWRESET_SYSTEM */
+			.value = 0x00000002,
+			.valid = true,
+		},
+		[REBOOT_SOFT] = {
+			.offset = 0x3a00, /* SYSTEM_CONFIGURATION */
+			.mask = 0x00000002, /* SWRESET_SYSTEM */
+			.value = 0x00000002,
+			.valid = true,
+		},
+	},
+	.catchall = {
+		.offset = 0x3e9c, /* PAD_CTRL_PWR_HOLD */
+		.mask = 0x00000100,
+		.value = 0x00000000,
+	},
+};
+
+static const struct of_device_id syscon_reboot_of_match[] = {
+	{ .compatible = "google,gs101-reboot", .data = &gs101_reboot_data  },
+	{ .compatible = "syscon-reboot" },
+	{}
+};
+
+static struct platform_driver syscon_reboot_driver = {
+	.probe = syscon_reboot_probe,
+	.driver = {
+		.name = "syscon-reboot",
+		.of_match_table = syscon_reboot_of_match,
+	},
+};
+builtin_platform_driver(syscon_reboot_driver);