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, 75 insertions, 0 deletions

diff --git a/drivers/leds/TODO b/drivers/leds/TODO
new file mode 100644
index 000000000..bfa60fa1d
--- /dev/null
+++ b/drivers/leds/TODO
@@ -0,0 +1,75 @@
+-*- org -*-
+
+* On/off LEDs should have max_brightness of 1
+* Get rid of enum led_brightness
+
+It is really an integer, as maximum is configurable. Get rid of it, or
+make it into typedef or something.
+
+* Review atomicity requirements in LED subsystem
+
+Calls that may and that may not block are mixed in same structure, and
+semantics is sometimes non-intuitive. (For example blink callback may
+not sleep.) Review the requirements for any bugs and document them
+clearly.
+
+* LED names are still a mess
+
+No two LEDs have same name, so the names are probably unusable for the
+userland. Nudge authors into creating common LED names for common
+functionality.
+
+? Perhaps check for known LED names during boot, and warn if there are
+LEDs not on the list?
+
+* Split drivers into subdirectories
+
+The number of drivers is getting big, and driver for on/off LED on a
+i/o port is really quite different from camera flash LED, which is
+really different from driver for RGB color LED that can run its own
+microcode. Split the drivers somehow.
+
+* Figure out what to do with RGB leds
+
+Multicolor is a bit too abstract. Yes, we can have
+Green-Magenta-Ultraviolet LED, but so far all the LEDs we support are
+RGB, and not even RGB-White or RGB-Yellow variants emerged.
+
+Multicolor is not a good fit for RGB LED. It does not really know
+about LED color.  In particular, there's no way to make LED "white".
+
+Userspace is interested in knowing "this LED can produce arbitrary
+color", which not all multicolor LEDs can.
+
+	Proposal: let's add "rgb" to led_colors in drivers/leds/led-core.c,
+	add corresponding device tree defines, and use that, instead of
+	multicolor for RGB LEDs.
+
+	We really need to do that now; "white" stuff can wait.
+
+RGB LEDs are quite common, and it would be good to be able to turn LED
+white and to turn it into any arbitrary color. It is essential that
+userspace is able to set arbitrary colors, and it might be good to
+have that ability from kernel, too... to allow full-color triggers.
+
+* Command line utility to manipulate the LEDs?
+
+/sys interface is not really suitable to use by hand, should we have
+an utility to perform LED control?
+
+In particular, LED names are still a mess (see above) and utility
+could help there by presenting both old and new names while we clean
+them up.
+
+In future, I'd like utility to accept both old and new names while we
+clean them up.
+
+It would be also nice to have useful listing mode -- name, type,
+current brightness/trigger...
+
+In future, it would be good to be able to set rgb led to particular
+color.
+
+And probably user-friendly interface to access LEDs for particular
+ethernet interface would be nice.
+