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, 114 insertions, 0 deletions

diff --git a/drivers/base/module.c b/drivers/base/module.c
new file mode 100644
index 000000000..6789dca48
--- /dev/null
+++ b/drivers/base/module.c
@@ -0,0 +1,114 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * module.c - module sysfs fun for drivers
+ */
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/errno.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include "base.h"
+
+static char *make_driver_name(const struct device_driver *drv)
+{
+	char *driver_name;
+
+	driver_name = kasprintf(GFP_KERNEL, "%s:%s", drv->bus->name, drv->name);
+	if (!driver_name)
+		return NULL;
+
+	return driver_name;
+}
+
+static void module_create_drivers_dir(struct module_kobject *mk)
+{
+	static DEFINE_MUTEX(drivers_dir_mutex);
+
+	mutex_lock(&drivers_dir_mutex);
+	if (mk && !mk->drivers_dir)
+		mk->drivers_dir = kobject_create_and_add("drivers", &mk->kobj);
+	mutex_unlock(&drivers_dir_mutex);
+}
+
+int module_add_driver(struct module *mod, const struct device_driver *drv)
+{
+	char *driver_name;
+	struct module_kobject *mk = NULL;
+	int ret;
+
+	if (!drv)
+		return 0;
+
+	if (mod)
+		mk = &mod->mkobj;
+	else if (drv->mod_name) {
+		/* Lookup or create built-in module entry in /sys/module */
+		mk = lookup_or_create_module_kobject(drv->mod_name);
+		if (mk) {
+			/* remember our module structure */
+			drv->p->mkobj = mk;
+			/* lookup_or_create_module_kobject took a reference */
+			kobject_put(&mk->kobj);
+		}
+	}
+
+	if (!mk)
+		return 0;
+
+	ret = sysfs_create_link(&drv->p->kobj, &mk->kobj, "module");
+	if (ret)
+		return ret;
+
+	driver_name = make_driver_name(drv);
+	if (!driver_name) {
+		ret = -ENOMEM;
+		goto out_remove_kobj;
+	}
+
+	module_create_drivers_dir(mk);
+	if (!mk->drivers_dir) {
+		ret = -EINVAL;
+		goto out_free_driver_name;
+	}
+
+	ret = sysfs_create_link(mk->drivers_dir, &drv->p->kobj, driver_name);
+	if (ret)
+		goto out_remove_drivers_dir;
+
+	kfree(driver_name);
+
+	return 0;
+
+out_remove_drivers_dir:
+	sysfs_remove_link(mk->drivers_dir, driver_name);
+
+out_free_driver_name:
+	kfree(driver_name);
+
+out_remove_kobj:
+	sysfs_remove_link(&drv->p->kobj, "module");
+	return ret;
+}
+
+void module_remove_driver(const struct device_driver *drv)
+{
+	struct module_kobject *mk = NULL;
+	char *driver_name;
+
+	if (!drv)
+		return;
+
+	sysfs_remove_link(&drv->p->kobj, "module");
+
+	if (drv->owner)
+		mk = &drv->owner->mkobj;
+	else if (drv->p->mkobj)
+		mk = drv->p->mkobj;
+	if (mk && mk->drivers_dir) {
+		driver_name = make_driver_name(drv);
+		if (driver_name) {
+			sysfs_remove_link(mk->drivers_dir, driver_name);
+			kfree(driver_name);
+		}
+	}
+}