fix #28612342

commit d44f1b8dd7e66d80cc4205809e5ace866bd851da upstream

To split up APEIs in_nmi() path, the caller needs to always be
in_nmi(). Add a helper to do the work and claim the notification.

When KVM or the arch code takes an exception that might be a RAS
notification, it asks the APEI firmware-first code whether it wants
to claim the exception. A future kernel-first mechanism may be queried
afterwards, and claim the notification, otherwise we fall through
to the existing default behaviour.

The NOTIFY_SEA code was merged before considering multiple, possibly
interacting, NMI-like notifications and the need to consider kernel
first in the future. Make the 'claiming' behaviour explicit.

Restructuring the APEI code to allow multiple NMI-like notifications
means any notification that might interrupt interrupts-masked
code must always be wrapped in nmi_enter()/nmi_exit(). This will
allow APEI to use in_nmi() to use the right fixmap entries.

Mask SError over this window to prevent an asynchronous RAS error
arriving and tripping 'nmi_enter()'s BUG_ON(in_nmi()).
Signed-off-by: NJames Morse <james.morse@arm.com>
Acked-by: NMarc Zyngier <marc.zyngier@arm.com>
Tested-by: NTyler Baicar <tbaicar@codeaurora.org>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: NBaolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: NAlex Shi <alex.shi@linux.alibaba.com>
Acked-by: NCaspar Zhang <caspar@linux.alibaba.com>
Reviewed-by: Nluanshi <zhangliguang@linux.alibaba.com>

Remove the local_{async,fiq}_{en,dis}able macros as they don't respect
our newly defined order and are only used to set the flags for process
context when we bring CPUs online.

Add a helper to do this. The IRQ flag varies as we want it masked on
the boot CPU until we are ready to handle interrupts.
The boot CPU unmasks SError during early boot once it can print an error
message. If we can print an error message about SError, we can do the
same for FIQ. Debug exceptions are already enabled by __cpu_setup(),
which has also configured MDSCR_EL1 to disable MDE and KDE.
Signed-off-by: NJames Morse <james.morse@arm.com>
Reviewed-by: NJulien Thierry <julien.thierry@arm.com>
Reviewed-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>

There are a few places where we want to mask all exceptions. Today we
do this in a piecemeal fashion, typically we expect the caller to
have masked irqs and the arch code masks debug exceptions, ignoring
serror which is probably masked.

Make it clear that 'mask all exceptions' is the intention by adding
helpers to do exactly that.

This will let us unmask SError without having to add 'oh and SError'
to these paths.
Signed-off-by: NJames Morse <james.morse@arm.com>
Reviewed-by: NJulien Thierry <julien.thierry@arm.com>
Reviewed-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NWill Deacon <will.deacon@arm.com>