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, 40 insertions, 0 deletions

diff --git a/drivers/char/nwbutton.h b/drivers/char/nwbutton.h
new file mode 100644
index 000000000..f2b9fdc1f
--- /dev/null
+++ b/drivers/char/nwbutton.h
@@ -0,0 +1,40 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __NWBUTTON_H
+#define __NWBUTTON_H
+
+/*
+ * 	NetWinder Button Driver-
+ *	Copyright (C) Alex Holden <alex@linuxhacker.org> 1998, 1999.
+ */
+
+#ifdef __NWBUTTON_C	/* Actually compiling the driver itself */
+
+/* Various defines: */
+
+#define NUM_PRESSES_REBOOT 2	/* How many presses to activate shutdown */
+#define BUTTON_DELAY 30 	/* How many jiffies for sequence to end */
+#define VERSION "0.3"		/* Driver version number */
+
+/* Structure definitions: */
+
+struct button_callback {
+	void (*callback) (void);
+	int count;
+};
+
+/* Function prototypes: */
+
+static void button_sequence_finished(struct timer_list *unused);
+static irqreturn_t button_handler (int irq, void *dev_id);
+int button_init (void);
+int button_add_callback (void (*callback) (void), int count);
+int button_del_callback (void (*callback) (void));
+static void button_consume_callbacks (int bpcount);
+
+#else /* Not compiling the driver itself */
+
+extern int button_add_callback (void (*callback) (void), int count);
+extern int button_del_callback (void (*callback) (void));
+
+#endif /* __NWBUTTON_C */
+#endif /* __NWBUTTON_H */