Hi guys, kbuild-robot,
This RFC is rough, and not at all ready. This is the current status of
my attempts to split up the ghes.c code to allow multiple notifications
to be NMI-like. On arm64 we have NOTIFY_{SEA, SEI, SDEI} all of which
have NMI-like behaviour.
This series splits up APEIs in_nmi() path so that more than one
notification can use it. To support the asyncronous notifications: SEI
and SDEI we move all the NMI-like handlers over to the estatus-cache.
This gives us the same APEI behaviour as x86, and means the multiple
notification methods can interact if firmware implements more than one.
estatus.. queue? ghes.c has three things all called 'estatus'. One is
a pool of memory that has a static size, and is grown/shrunk when new
NMI users are allocated. The second is the cache, this holds recent
notifications so it can suppress notifications we've already handled.
The last is the queue, which holds data from NMI notifications (in pool
memory) that can't be handled immediatly.
So far this has only been tested using SDEI.
This RFC makes a know race worse. (I aim to fix the race before dropping
the RFC tag). Xie XiuQi reported that both the arch code and
memory_failure() will signal an affected process, what the process gets
depends on the order these run in, and how the signals get merged.
Using the estatus-cache makes this worse. My intention is for the arch
code's new 'apei_claim_x()' helpers to give any queue that the claimed
RAS event may be stuck in a kick, depending on which irq/preemptible
flags the notification caused to be set.
Your CC list is wrong! Yes, given how ropey this is I want to keep the
noise low, it would only need posting again at rc1.
Comments on the overall approach welcome!
Thanks,
James Morse (7):
ACPI / APEI: Move the estatus queue code up, and under its own ifdef
ACPI / APEI: Generalise the estatus queue's add/remove and notify code
ACPI / APEI: Switch NOTIFY_SEA to use the estatus queue
KVM: arm/arm64: Add kvm_ras.h to collect kvm specific RAS plumbing
arm64: KVM/mm: Move SEA handling behind a single 'claim' interface.
ACPI / APEI: Make the fixmap_idx per-ghes to allow multiple in_nmi()
users
ACPI / APEI: Split fixmap pages for arm64 NMI-like notifications
arch/arm/include/asm/kvm_ras.h | 14 ++
arch/arm/include/asm/system_misc.h | 5 -
arch/arm64/include/asm/acpi.h | 2 +
arch/arm64/include/asm/daifflags.h | 1 +
arch/arm64/include/asm/fixmap.h | 4 +-
arch/arm64/include/asm/kvm_ras.h | 23 ++
arch/arm64/include/asm/system_misc.h | 2 -
arch/arm64/kernel/acpi.c | 30 +++
arch/arm64/mm/fault.c | 30 +--
drivers/acpi/apei/ghes.c | 467 ++++++++++++++++++-----------------
include/acpi/ghes.h | 5 +
virt/kvm/arm/mmu.c | 4 +-
12 files changed, 327 insertions(+), 260 deletions(-)
create mode 100644 arch/arm/include/asm/kvm_ras.h
create mode 100644 arch/arm64/include/asm/kvm_ras.h
--
2.15.1
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