On Tuesday, June 26, 2018 7:00:56 PM CEST James Morse wrote: > The aim of this series is to wire arm64's SDEI into APEI. > > On arm64 we have three APEI notifications that are NMI-like, and > in the unlikely event that all three are supported by a platform, > they can interrupt each other. > The GHES driver shouldn't have to deal with this, so this series aims > to make it re-entrant. > > To do that, we refactor the estatus queue to allow multiple notifications > to use it, then convert NOTIFY_SEA to always be described as NMI-like, > and to use the estatus queue. > > From here we push the locking and fixmap choices out to the notification > functions, and remove the use of per-ghes estatus and flags. This removes > the in_nmi() 'timebomb' in ghes_copy_tofrom_phys(). > > Things get sticky when an NMI notification needs to know how big the > CPER records might be, before reading it. This series splits > ghes_estatus_read() to let us peek at the buffer. A side effect of this > is the 20byte header will get read twice. (how does it work today? it > reads the records into a per-ghes worst-case sized buffer, allocates > the correct size and copies the records. in_nmi() use of this per-ghes > buffer needs eliminating). > > One alternative was to trust firmware's 'max raw data length' and use > that to allocate 'enough' memory. We don't use this value today, so its > probably wrong on some sytem somewhere. > > Since v4 patches 5,8-15 are new, otherwise changes are noted in the patch. > > > The earlier boiler-plate: > > What's SDEI? Its ARM's "Software Delegated Exception Interface" [0]. It's > used by firmware to tell the OS about firmware-first RAS events. > > These Software exceptions can interrupt anything, so I describe them as > NMI-like. They aren't the only NMI-like way to notify the OS about > firmware-first RAS events, the ACPI spec also defines 'NOTFIY_SEA' and > 'NOTIFY_SEI'. > > (Acronyms: SEA, Synchronous External Abort. The CPU requested some memory, > but the owner of that memory said no. These are always synchronous with the > instruction that caused them. SEI, System-Error Interrupt, commonly called > SError. This is an asynchronous external abort, the memory-owner didn't say no > at the right point. Collectively these things are called external-aborts > How is firmware involved? It traps these and re-injects them into the kernel > once its written the CPER records). > > APEI's GHES code only expects one source of NMI. If a platform implements > more than one of these mechanisms, APEI needs to handle the interaction. > 'SEA' and 'SEI' can interact as 'SEI' is asynchronous. SDEI can interact > with itself: its exceptions can be 'normal' or 'critical', and firmware > could use both types for RAS. (errors using normal, 'panic-now' using > critical). > > > ghes.c became clearer to me when I worked out that it has three sets of > functions with 'estatus' in the name. One is a pool of memory that can be > allocated-from atomically. This is grown/shrunk when new NMI users are > allocated. > The second is the estatus-cache, which holds recent notifications so it > can suppress notifications we've already handled. > The last it the estatus-queue, which holds data from NMI-like notifications > (in pool memory) to be processed from irq_work. > > > Testing? > Tested with the SDEI FVP based software model and a mocked up NOTFIY_SEA using > KVM. I've added a case where 'corrected errors' are discovered at probe time > to exercise ghes_probe() during boot. I've only build tested this on x86. > > This series based on v4.18-rc2 can be retrieved from: > git://linux-arm.org/linux-jm.git -b apei_sdei/v5 > > > Thanks, > > James > > [0] http://infocenter.arm.com/help/topic/com.arm.doc.den0054a/ARM_DEN0054A_Software_Delegated_Exception_Interface.pdf > > James Morse (20): > 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: don't wait to serialise with oops messages when > panic()ing > ACPI / APEI: Switch NOTIFY_SEA to use the estatus queue > ACPI / APEI: Make estatus queue a Kconfig symbol > 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: Move locking to the notification helper > ACPI / APEI: Let the notification helper specify the fixmap slot > ACPI / APEI: preparatory split of ghes->estatus > ACPI / APEI: Remove silent flag from ghes_read_estatus() > ACPI / APEI: Don't store CPER records physical address in struct ghes > ACPI / APEI: Don't update struct ghes' flags in read/clear estatus > ACPI / APEI: Split ghes_read_estatus() to read CPER length > ACPI / APEI: Only use queued estatus entry during _in_nmi_notify_one() > ACPI / APEI: Split fixmap pages for arm64 NMI-like notifications > firmware: arm_sdei: Add ACPI GHES registration helper > ACPI / APEI: Add support for the SDEI GHES Notification type > mm/memory-failure: increase queued recovery work's priority > arm64: acpi: Make apei_claim_sea() synchronise with APEI's irq work > > arch/arm/include/asm/kvm_ras.h | 14 + > arch/arm/include/asm/system_misc.h | 5 - > arch/arm64/include/asm/acpi.h | 4 + > arch/arm64/include/asm/daifflags.h | 1 + > arch/arm64/include/asm/fixmap.h | 8 +- > arch/arm64/include/asm/kvm_ras.h | 25 ++ > arch/arm64/include/asm/system_misc.h | 2 - > arch/arm64/kernel/acpi.c | 49 ++ > arch/arm64/mm/fault.c | 30 +- > drivers/acpi/apei/Kconfig | 11 + > drivers/acpi/apei/ghes.c | 649 ++++++++++++++++----------- > drivers/firmware/Kconfig | 1 + > drivers/firmware/arm_sdei.c | 66 +++ > include/acpi/ghes.h | 2 - > include/linux/arm_sdei.h | 9 + > mm/memory-failure.c | 11 +- > virt/kvm/arm/mmu.c | 4 +- > 17 files changed, 591 insertions(+), 300 deletions(-) > create mode 100644 arch/arm/include/asm/kvm_ras.h > create mode 100644 arch/arm64/include/asm/kvm_ras.h Tony, I need your help with reviewing the APEI-related material here. Can you please have a look at this series and let me know if there are any concerns regarding it? Thanks, Rafael
