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, 49 insertions, 0 deletions

diff --git a/include/acpi/pcc.h b/include/acpi/pcc.h
new file mode 100644
index 000000000..840bfc95b
--- /dev/null
+++ b/include/acpi/pcc.h
@@ -0,0 +1,49 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * PCC (Platform Communications Channel) methods
+ */
+
+#ifndef _PCC_H
+#define _PCC_H
+
+#include <linux/mailbox_controller.h>
+#include <linux/mailbox_client.h>
+
+struct pcc_mbox_chan {
+	struct mbox_chan *mchan;
+	u64 shmem_base_addr;
+	void __iomem *shmem;
+	u64 shmem_size;
+	u32 latency;
+	u32 max_access_rate;
+	u16 min_turnaround_time;
+};
+
+/* Generic Communications Channel Shared Memory Region */
+#define PCC_SIGNATURE			0x50434300
+/* Generic Communications Channel Command Field */
+#define PCC_CMD_GENERATE_DB_INTR	BIT(15)
+/* Generic Communications Channel Status Field */
+#define PCC_STATUS_CMD_COMPLETE		BIT(0)
+#define PCC_STATUS_SCI_DOORBELL		BIT(1)
+#define PCC_STATUS_ERROR		BIT(2)
+#define PCC_STATUS_PLATFORM_NOTIFY	BIT(3)
+/* Initiator Responder Communications Channel Flags */
+#define PCC_CMD_COMPLETION_NOTIFY	BIT(0)
+
+#define MAX_PCC_SUBSPACES	256
+
+#ifdef CONFIG_PCC
+extern struct pcc_mbox_chan *
+pcc_mbox_request_channel(struct mbox_client *cl, int subspace_id);
+extern void pcc_mbox_free_channel(struct pcc_mbox_chan *chan);
+#else
+static inline struct pcc_mbox_chan *
+pcc_mbox_request_channel(struct mbox_client *cl, int subspace_id)
+{
+	return ERR_PTR(-ENODEV);
+}
+static inline void pcc_mbox_free_channel(struct pcc_mbox_chan *chan) { }
+#endif
+
+#endif /* _PCC_H */