Re: [PATCH 05/11] arm64: KVM/mm: Move SEA handling behind a single 'claim' interface

[Punit Agrawal <punit.agrawal@arm.com>]

One typo in the commit log otherwise looks good.

James Morse <james.morse@arm.com> writes:

> To split up APEIs in_nmi() path, we need the nmi-like callers 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. We can then go on to see if (a future)
> kernel-first mechanism wants to claim the notification, before
> falling through to the existing default behaviour.
>
> The NOTIFY_SEA code was merged before we had multiple, possibly
> interacting, NMI-like notifications and the need to consider kernel
> first in the future. Make the 'claiming' behaviour explicit.
>
> As we're restructuring the APEI code to allow multiple NMI-like
> notifications, any notification that might interrupt interrupts-masked
> code must always be wrapped in nmi_enter()/nmi_exit(). This allows APEI
> to use in_nmi() so choose between the raw/regular spinlock routines.
                  ^
                  to

Thanks,
Punit

>
> We mask SError over this window to prevent an asynchronous RAS error
> arriving and tripping 'nmi_enter()'s BUG_ON(in_nmi()).
>
> Signed-off-by: James Morse <james.morse@arm.com>
> CC: Tyler Baicar <tbaicar@codeaurora.org>
> ---
> Why does apei_claim_sea() take a pt_regs? This gets used later to take
> APEI by the hand through NMI->IRQ context, depending on what we
> interrupted.
>
>  arch/arm64/include/asm/acpi.h      |  3 +++
>  arch/arm64/include/asm/daifflags.h |  1 +
>  arch/arm64/include/asm/kvm_ras.h   | 20 +++++++++++++++++++-
>  arch/arm64/kernel/acpi.c           | 30 ++++++++++++++++++++++++++++++
>  arch/arm64/mm/fault.c              | 31 +++++++------------------------
>  5 files changed, 60 insertions(+), 25 deletions(-)
>

[...]

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