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, 120 insertions, 0 deletions

diff --git a/include/uapi/sound/fcp.h b/include/uapi/sound/fcp.h
new file mode 100644
index 000000000..aea428956
--- /dev/null
+++ b/include/uapi/sound/fcp.h
@@ -0,0 +1,120 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Focusrite Control Protocol Driver for ALSA
+ *
+ * Copyright (c) 2024-2025 by Geoffrey D. Bennett <g at b4.vu>
+ */
+/*
+ * DOC: FCP (Focusrite Control Protocol) User-Space API
+ *
+ * This header defines the interface between the FCP kernel driver and
+ * user-space programs to enable the use of the proprietary features
+ * available in Focusrite USB audio interfaces. This includes Scarlett
+ * 2nd Gen, 3rd Gen, 4th Gen, Clarett USB, Clarett+, and Vocaster
+ * series devices.
+ *
+ * The interface is provided via ALSA's hwdep interface. Opening the
+ * hwdep device requires CAP_SYS_RAWIO privileges as this interface
+ * provides near-direct access.
+ *
+ * For details on the FCP protocol, refer to the kernel scarlett2
+ * driver in sound/usb/mixer_scarlett2.c and the fcp-support project
+ * at https://github.com/geoffreybennett/fcp-support
+ *
+ * For examples of using these IOCTLs, see the fcp-server source in
+ * the fcp-support project.
+ *
+ * IOCTL Interface
+ * --------------
+ * FCP_IOCTL_PVERSION:
+ *   Returns the protocol version supported by the driver.
+ *
+ * FCP_IOCTL_INIT:
+ *   Initialises the protocol and synchronises sequence numbers
+ *   between the driver and device. Must be called at least once
+ *   before sending commands. Can be safely called again at any time.
+ *
+ * FCP_IOCTL_CMD:
+ *   Sends an FCP command to the device and returns the response.
+ *   Requires prior initialisation via FCP_IOCTL_INIT.
+ *
+ * FCP_IOCTL_SET_METER_MAP:
+ *   Configures the Level Meter control's mapping between device
+ *   meters and control channels. Requires FCP_IOCTL_INIT to have been
+ *   called first. The map size and number of slots cannot be changed
+ *   after initial configuration, although the map itself can be
+ *   updated. Once configured, the Level Meter remains functional even
+ *   after the hwdep device is closed.
+ *
+ * FCP_IOCTL_SET_METER_LABELS:
+ *   Set the labels for the Level Meter control. Requires
+ *   FCP_IOCTL_SET_METER_MAP to have been called first. labels[]
+ *   should contain a sequence of null-terminated labels corresponding
+ *   to the control's channels.
+ */
+#ifndef __UAPI_SOUND_FCP_H
+#define __UAPI_SOUND_FCP_H
+
+#include <linux/types.h>
+#include <linux/ioctl.h>
+
+#define FCP_HWDEP_MAJOR 2
+#define FCP_HWDEP_MINOR 0
+#define FCP_HWDEP_SUBMINOR 0
+
+#define FCP_HWDEP_VERSION \
+	((FCP_HWDEP_MAJOR << 16) | \
+	 (FCP_HWDEP_MINOR << 8) | \
+	  FCP_HWDEP_SUBMINOR)
+
+#define FCP_HWDEP_VERSION_MAJOR(v) (((v) >> 16) & 0xFF)
+#define FCP_HWDEP_VERSION_MINOR(v) (((v) >> 8) & 0xFF)
+#define FCP_HWDEP_VERSION_SUBMINOR(v) ((v) & 0xFF)
+
+/* Get protocol version */
+#define FCP_IOCTL_PVERSION _IOR('S', 0x60, int)
+
+/* Start the protocol */
+
+/* Step 0 and step 2 responses are variable length and placed in
+ * resp[] one after the other.
+ */
+struct fcp_init {
+	__u16 step0_resp_size;
+	__u16 step2_resp_size;
+	__u32 init1_opcode;
+	__u32 init2_opcode;
+	__u8  resp[];
+} __attribute__((packed));
+
+#define FCP_IOCTL_INIT _IOWR('S', 0x64, struct fcp_init)
+
+/* Perform a command */
+
+/* The request data is placed in data[] and the response data will
+ * overwrite it.
+ */
+struct fcp_cmd {
+	__u32 opcode;
+	__u16 req_size;
+	__u16 resp_size;
+	__u8  data[];
+} __attribute__((packed));
+#define FCP_IOCTL_CMD _IOWR('S', 0x65, struct fcp_cmd)
+
+/* Set the meter map */
+struct fcp_meter_map {
+	__u16 map_size;
+	__u16 meter_slots;
+	__s16 map[];
+} __attribute__((packed));
+#define FCP_IOCTL_SET_METER_MAP _IOW('S', 0x66, struct fcp_meter_map)
+
+/* Set the meter labels */
+struct fcp_meter_labels {
+	__u16 labels_size;
+	char  labels[];
+} __attribute__((packed));
+#define FCP_IOCTL_SET_METER_LABELS _IOW('S', 0x67, struct fcp_meter_labels)
+
+#endif /* __UAPI_SOUND_FCP_H */