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, 102 insertions, 0 deletions

diff --git a/drivers/mtd/chips/chipreg.c b/drivers/mtd/chips/chipreg.c
new file mode 100644
index 000000000..a05e10368
--- /dev/null
+++ b/drivers/mtd/chips/chipreg.c
@@ -0,0 +1,102 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Registration for chip drivers
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/kmod.h>
+#include <linux/spinlock.h>
+#include <linux/slab.h>
+#include <linux/mtd/map.h>
+#include <linux/mtd/mtd.h>
+
+static DEFINE_SPINLOCK(chip_drvs_lock);
+static LIST_HEAD(chip_drvs_list);
+
+void register_mtd_chip_driver(struct mtd_chip_driver *drv)
+{
+	spin_lock(&chip_drvs_lock);
+	list_add(&drv->list, &chip_drvs_list);
+	spin_unlock(&chip_drvs_lock);
+}
+
+void unregister_mtd_chip_driver(struct mtd_chip_driver *drv)
+{
+	spin_lock(&chip_drvs_lock);
+	list_del(&drv->list);
+	spin_unlock(&chip_drvs_lock);
+}
+
+static struct mtd_chip_driver *get_mtd_chip_driver (const char *name)
+{
+	struct mtd_chip_driver *ret = NULL, *this;
+
+	spin_lock(&chip_drvs_lock);
+
+	list_for_each_entry(this, &chip_drvs_list, list) {
+		if (!strcmp(this->name, name)) {
+			ret = this;
+			break;
+		}
+	}
+	if (ret && !try_module_get(ret->module))
+		ret = NULL;
+
+	spin_unlock(&chip_drvs_lock);
+
+	return ret;
+}
+
+	/* Hide all the horrid details, like some silly person taking
+	   get_module_symbol() away from us, from the caller. */
+
+struct mtd_info *do_map_probe(const char *name, struct map_info *map)
+{
+	struct mtd_chip_driver *drv;
+	struct mtd_info *ret;
+
+	drv = get_mtd_chip_driver(name);
+
+	if (!drv && !request_module("%s", name))
+		drv = get_mtd_chip_driver(name);
+
+	if (!drv)
+		return NULL;
+
+	ret = drv->probe(map);
+
+	/* We decrease the use count here. It may have been a
+	   probe-only module, which is no longer required from this
+	   point, having given us a handle on (and increased the use
+	   count of) the actual driver code.
+	*/
+	module_put(drv->module);
+
+	return ret;
+}
+/*
+ * Destroy an MTD device which was created for a map device.
+ * Make sure the MTD device is already unregistered before calling this
+ */
+void map_destroy(struct mtd_info *mtd)
+{
+	struct map_info *map = mtd->priv;
+
+	if (map->fldrv->destroy)
+		map->fldrv->destroy(mtd);
+
+	module_put(map->fldrv->module);
+
+	kfree(mtd);
+}
+
+EXPORT_SYMBOL(register_mtd_chip_driver);
+EXPORT_SYMBOL(unregister_mtd_chip_driver);
+EXPORT_SYMBOL(do_map_probe);
+EXPORT_SYMBOL(map_destroy);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("David Woodhouse <dwmw2@infradead.org>");
+MODULE_DESCRIPTION("Core routines for registering and invoking MTD chip drivers");