arm64: smp: avoid NMI IPIs with broken MediaTek FW

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:

  44bd78dd2b8897f5 ("irqchip/gic-v3: Disable pseudo NMIs on Mediatek devices w/ firmware issues")

We did not take this problem into account in commit:

  331a1b3a836c0f38 ("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: 331a1b3a836c ("arm64: smp: Add arch support for backtrace using pseudo-NMI")
Reported-by: Chen-Yu Tsai <[email protected]>
Closes: https://issuetracker.google.com/issues/197061987#comment68
Signed-off-by: Mark Rutland <[email protected]>
Reviewed-by: Douglas Anderson <[email protected]>
Tested-by: Douglas Anderson <[email protected]>
Reviewed-by: Marc Zyngier <[email protected]>
Tested-by: Chen-Yu Tsai <[email protected]>
Signed-off-by: Catalin Marinas <[email protected]>