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Mark Rutland a07a594152 arm64: smp: avoid NMI IPIs with broken MediaTek FW
Some MediaTek devices have broken firmware which corrupts some GICR
registers behind the back of the OS, and pseudo-NMIs cannot be used on
these devices. For more details see commit:

  44bd78dd2b ("irqchip/gic-v3: Disable pseudo NMIs on Mediatek devices w/ firmware issues")

We did not take this problem into account in commit:

  331a1b3a83 ("arm64: smp: Add arch support for backtrace using pseudo-NMI")

Since that commit arm64's SMP code will try to setup some IPIs as
pseudo-NMIs, even on systems with broken FW. The GICv3 code will
(rightly) reject attempts to request interrupts as pseudo-NMIs,
resulting in boot-time failures.

Avoid the problem by taking the broken FW into account when deciding to
request IPIs as pseudo-NMIs. The GICv3 driver maintains a static_key
named "supports_pseudo_nmis" which is false on systems with broken FW,
and we can consult this within ipi_should_be_nmi().

Fixes: 331a1b3a83 ("arm64: smp: Add arch support for backtrace using pseudo-NMI")
Reported-by: Chen-Yu Tsai <wenst@chromium.org>
Closes: https://issuetracker.google.com/issues/197061987#comment68
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Tested-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Tested-by: Chen-Yu Tsai <wenst@chromium.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
2023-10-06 12:34:41 +01:00
arch arm64: smp: avoid NMI IPIs with broken MediaTek FW 2023-10-06 12:34:41 +01:00
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