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, 48 insertions, 0 deletions

diff --git a/drivers/cpufreq/speedstep-lib.h b/drivers/cpufreq/speedstep-lib.h
new file mode 100644
index 000000000..48329647d
--- /dev/null
+++ b/drivers/cpufreq/speedstep-lib.h
@@ -0,0 +1,48 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * (C) 2002 - 2003 Dominik Brodowski <linux@brodo.de>
+ *
+ *  Library for common functions for Intel SpeedStep v.1 and v.2 support
+ *
+ *  BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
+ */
+
+
+
+/* processors */
+enum speedstep_processor {
+	SPEEDSTEP_CPU_PIII_C_EARLY = 0x00000001,  /* Coppermine core */
+	SPEEDSTEP_CPU_PIII_C	   = 0x00000002,  /* Coppermine core */
+	SPEEDSTEP_CPU_PIII_T	   = 0x00000003,  /* Tualatin core */
+	SPEEDSTEP_CPU_P4M	   = 0x00000004,  /* P4-M  */
+/* the following processors are not speedstep-capable and are not auto-detected
+ * in speedstep_detect_processor(). However, their speed can be detected using
+ * the speedstep_get_frequency() call. */
+	SPEEDSTEP_CPU_PM	   = 0xFFFFFF03,  /* Pentium M  */
+	SPEEDSTEP_CPU_P4D	   = 0xFFFFFF04,  /* desktop P4  */
+	SPEEDSTEP_CPU_PCORE	   = 0xFFFFFF05,  /* Core */
+};
+
+/* speedstep states -- only two of them */
+
+#define SPEEDSTEP_HIGH	0x00000000
+#define SPEEDSTEP_LOW	0x00000001
+
+
+/* detect a speedstep-capable processor */
+extern enum speedstep_processor speedstep_detect_processor(void);
+
+/* detect the current speed (in khz) of the processor */
+extern unsigned int speedstep_get_frequency(enum speedstep_processor processor);
+
+
+/* detect the low and high speeds of the processor. The callback
+ * set_state"'s first argument is either SPEEDSTEP_HIGH or
+ * SPEEDSTEP_LOW; the second argument is zero so that no
+ * cpufreq_notify_transition calls are initiated.
+ */
+extern int speedstep_get_freqs(enum speedstep_processor processor,
+			       unsigned int *low_speed,
+			       unsigned int *high_speed,
+			       unsigned int *transition_latency,
+			       void (*set_state)(unsigned int state));