On Mon, Sep 26, 2022 at 03:51:14PM +0100, Marc Zyngier wrote: > [Same distribution list as Gavin's dirty-ring on arm64 series] > > This is an update on the initial series posted as [0]. > > As Gavin started posting patches enabling the dirty-ring infrastructure > on arm64 [1], it quickly became apparent that the API was never intended > to work on relaxed memory ordering architectures (owing to its x86 > origins). > > This series tries to retrofit some ordering into the existing API by: > > - relying on acquire/release semantics which are the default on x86, > but need to be explicit on arm64 > > - adding a new capability that indicate which flavor is supported, either > with explicit ordering (arm64) or both implicit and explicit (x86), > as suggested by Paolo at KVM Forum > > - documenting the requirements for this new capability on weakly ordered > architectures > > - updating the selftests to do the right thing > > Ideally, this series should be a prefix of Gavin's, plus a small change > to his series: > > diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig > index 0309b2d0f2da..7785379c5048 100644 > --- a/arch/arm64/kvm/Kconfig > +++ b/arch/arm64/kvm/Kconfig > @@ -32,7 +32,7 @@ menuconfig KVM > select KVM_VFIO > select HAVE_KVM_EVENTFD > select HAVE_KVM_IRQFD > - select HAVE_KVM_DIRTY_RING > + select HAVE_KVM_DIRTY_RING_ACQ_REL > select HAVE_KVM_MSI > select HAVE_KVM_IRQCHIP > select HAVE_KVM_IRQ_ROUTING > > This has been very lightly tested on an arm64 box with Gavin's v3 [2] series. > > * From v1: > - Repainted the config symbols and new capability so that their > naming is more acceptable and causes less churn > - Fixed a couple of blunders as pointed out by Peter and Paolo > - Updated the documentation > > [0] https://lore.kernel.org/r/20220922170133.2617189-1-maz@xxxxxxxxxx > [1] https://lore.kernel.org/lkml/YyiV%2Fl7O23aw5aaO@xz-m1.local/T/ > [2] https://lore.kernel.org/r/20220922003214.276736-1-gshan@xxxxxxxxxx > > Marc Zyngier (6): > KVM: Use acquire/release semantics when accessing dirty ring GFN state > KVM: Add KVM_CAP_DIRTY_LOG_RING_ACQ_REL capability and config option > KVM: x86: Select CONFIG_HAVE_KVM_DIRTY_RING_ACQ_REL > KVM: Document weakly ordered architecture requirements for dirty ring > KVM: selftests: dirty-log: Upgrade flag accesses to acquire/release > semantics > KVM: selftests: dirty-log: Use KVM_CAP_DIRTY_LOG_RING_ACQ_REL if > available Reviewed-by: Peter Xu <peterx@xxxxxxxxxx> Thanks! -- Peter Xu _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
