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, 62 insertions, 0 deletions

diff --git a/drivers/accessibility/speakup/thread.c b/drivers/accessibility/speakup/thread.c
new file mode 100644
index 000000000..2fc75e60f
--- /dev/null
+++ b/drivers/accessibility/speakup/thread.c
@@ -0,0 +1,62 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/kthread.h>
+#include <linux/wait.h>
+
+#include "spk_types.h"
+#include "speakup.h"
+#include "spk_priv.h"
+
+DECLARE_WAIT_QUEUE_HEAD(speakup_event);
+EXPORT_SYMBOL_GPL(speakup_event);
+
+int speakup_thread(void *data)
+{
+	unsigned long flags;
+	int should_break;
+	struct bleep our_sound;
+
+	our_sound.active = 0;
+	our_sound.freq = 0;
+	our_sound.jiffies = 0;
+
+	mutex_lock(&spk_mutex);
+	while (1) {
+		DEFINE_WAIT(wait);
+
+		while (1) {
+			spin_lock_irqsave(&speakup_info.spinlock, flags);
+			our_sound = spk_unprocessed_sound;
+			spk_unprocessed_sound.active = 0;
+			prepare_to_wait(&speakup_event, &wait,
+					TASK_INTERRUPTIBLE);
+			should_break = kthread_should_stop() ||
+				our_sound.active ||
+				(synth && synth->catch_up && synth->alive &&
+					(speakup_info.flushing ||
+					!synth_buffer_empty()));
+			spin_unlock_irqrestore(&speakup_info.spinlock, flags);
+			if (should_break)
+				break;
+			mutex_unlock(&spk_mutex);
+			schedule();
+			mutex_lock(&spk_mutex);
+		}
+		finish_wait(&speakup_event, &wait);
+		if (kthread_should_stop())
+			break;
+
+		if (our_sound.active)
+			kd_mksound(our_sound.freq, our_sound.jiffies);
+		if (synth && synth->catch_up && synth->alive) {
+			/*
+			 * It is up to the callee to take the lock, so that it
+			 * can sleep whenever it likes
+			 */
+			synth->catch_up(synth);
+		}
+
+		speakup_start_ttys();
+	}
+	mutex_unlock(&spk_mutex);
+	return 0;
+}