lkml.org 
[lkml]   [2019]   [Oct]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    Subject[PATCH V5 0/4] ACPI: Support Generic Initiator proximity domains
    Date
    Introduces a new type of NUMA node for cases where we want to represent
    the access characteristics of a non CPU initiator of memory requests,
    as these differ from all those for existing nodes containing CPUs and/or
    memory.

    This patch set has been sitting around for a long time (rebases only since
    v3 in April) without significant review.
    I would appreciate it very much if anyone has time to take a look.

    One outstanding question to highlight in this series is whether
    we should assume all ACPI supporting architectures support Generic
    Initiator domains, or whether to introduce an
    ARCH_HAS_GENERIC_INITIATOR_DOMAINS entry in Kconfig.

    Changes since V4:

    At Rafael's suggestion:

    Rebase on top of Dan William's Specific Purpose Memory series as that
    moves srat.c Original patches cherry-picked fine onto mmotm with Dan's
    patches applied.

    Applies to mmotm-2019-09-25 +
    https://lore.kernel.org/linux-acpi/156140036490.2951909.1837804994781523185.stgit@dwillia2-desk3.amr.corp.intel.com/
    [PATCH v4 00/10] EFI Specific Purpose Memory Support
    (note there are some trivial conflicts to deal with when applying
    the SPM series).

    Change since V3.
    * Rebase.

    Changes since RFC V2.
    * RFC dropped as now we have x86 support, so the lack of guards in in the
    ACPI code etc should now be fine.
    * Added x86 support. Note this has only been tested on QEMU as I don't have
    a convenient x86 NUMA machine to play with. Note that this fitted together
    rather differently from arm64 so I'm particularly interested in feedback
    on the two solutions.

    Since RFC V1.
    * Fix incorrect interpretation of the ACPI entry noted by Keith Busch
    * Use the acpica headers definitions that are now in mmotm.

    It's worth noting that, to safely put a given device in a GI node, may
    require changes to the existing drivers as it's not unusual to assume
    you have local memory or processor core. There may be further constraints
    not yet covered by this patch.

    Original cover letter...

    ACPI 6.3 introduced a new entity that can be part of a NUMA proximity domain.
    It may share such a domain with the existing options (memory, CPU etc) but it
    may also exist on it's own.

    The intent is to allow the description of the NUMA properties (particularly
    via HMAT) of accelerators and other initiators of memory activity that are not
    the host processor running the operating system.

    This patch set introduces 'just enough' to make them work for arm64 and x86.
    It should be trivial to support other architectures, I just don't suitable
    NUMA systems readily available to test.

    There are a few quirks that need to be considered.

    1. Fall back nodes
    ******************

    As pre ACPI 6.3 supporting operating systems do not have Generic Initiator
    Proximity Domains it is possible to specify, via _PXM in DSDT that another
    device is part of such a GI only node. This currently blows up spectacularly.

    Whilst we can obviously 'now' protect against such a situation (see the related
    thread on PCI _PXM support and the threadripper board identified there as
    also falling into the problem of using non existent nodes
    https://patchwork.kernel.org/patch/10723311/ ), there is no way to be sure
    we will never have legacy OSes that are not protected against this. It would
    also be 'non ideal' to fallback to a default node as there may be a better
    (non GI) node to pick if GI nodes aren't available.

    The work around is that we also have a new system wide OSC bit that allows
    an operating system to 'announce' that it supports Generic Initiators. This
    allows, the firmware to us DSDT magic to 'move' devices between the nodes
    dependent on whether our new nodes are there or not.

    2. New ways of assigning a proximity domain for devices
    *******************************************************

    Until now, the only way firmware could indicate that a particular device
    (outside the 'special' set of cpus etc) was to be found in a particular
    Proximity Domain by the use of _PXM in DSDT.

    That is equally valid with GI domains, but we have new options. The SRAT
    affinity structure includes a handle (ACPI or PCI) to identify devices
    with the system and specify their proximity domain that way. If both _PXM
    and this are provided, they should give the same answer.

    For now this patch set completely ignores that feature as we don't need
    it to start the discussion. It will form a follow up set at some point
    (if no one else fancies doing it).

    Jonathan Cameron (4):
    ACPI: Support Generic Initiator only domains
    arm64: Support Generic Initiator only domains
    x86: Support Generic Initiator only proximity domains
    ACPI: Let ACPI know we support Generic Initiator Affinity Structures

    arch/arm64/kernel/smp.c | 8 +++++
    arch/x86/include/asm/numa.h | 2 ++
    arch/x86/kernel/setup.c | 1 +
    arch/x86/mm/numa.c | 14 ++++++++
    drivers/acpi/bus.c | 1 +
    drivers/acpi/numa/srat.c | 62 +++++++++++++++++++++++++++++++++-
    drivers/base/node.c | 3 ++
    include/asm-generic/topology.h | 3 ++
    include/linux/acpi.h | 1 +
    include/linux/nodemask.h | 1 +
    include/linux/topology.h | 7 ++++
    11 files changed, 102 insertions(+), 1 deletion(-)

    --
    2.20.1

    \
     
     \ /
      Last update: 2019-10-04 13:45    [W:2.702 / U:0.416 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site