Hi, A gentle ping on this series. Please take a look and let me know the new approach taken in this revision is good enough or not. Appreciate your feedback. Thanks, Shameer > -----Original Message----- > From: linux-arm-kernel [mailto:linux-arm-kernel-bounces@xxxxxxxxxxxxxxxxxxx] > On Behalf Of Shameer Kolothum > Sent: 22 November 2021 12:19 > To: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; kvmarm@xxxxxxxxxxxxxxxxxxxxx; > linux-kernel@xxxxxxxxxxxxxxx > Cc: maz@xxxxxxxxxx; will@xxxxxxxxxx; catalin.marinas@xxxxxxx; > james.morse@xxxxxxx; julien.thierry.kdev@xxxxxxxxx; > suzuki.poulose@xxxxxxx; jean-philippe@xxxxxxxxxx; > Alexandru.Elisei@xxxxxxx; qperret@xxxxxxxxxx; Jonathan Cameron > <jonathan.cameron@xxxxxxxxxx>; Linuxarm <linuxarm@xxxxxxxxxx> > Subject: [PATCH v4 0/4] kvm/arm: New VMID allocator based on asid > > Changes from v3: > - Main change is in patch #4, where the VMID is now set to an > invalid one on vCPU schedule out. Introduced an > INVALID_ACTIVE_VMID which is basically a VMID 0 with generation 1. > Since the basic allocator algorithm reserves vmid #0, it is never > used as an active VMID. This (hopefully) will fix the issue of > unnecessarily reserving VMID space with active_vmids when those > VMs are no longer active[0] and at the same time address the > problem noted in v3 wherein everything ends up in slow-path[1]. > > Testing: > -Run with VMID bit set to 4 and maxcpus to 8 on D06. The test > involves running concurrently 50 guests with 4 vCPUs. Each > guest will then execute hackbench 5 times before exiting. > No crash was observed for a 4-day continuous run. > The latest branch is here, > https://github.com/hisilicon/kernel-dev/tree/private-v5.16-rc1-vmid-v4 > > -TLA+ model. Modified the asidalloc model to incorporate the new > VMID algo. The main differences are, > -flush_tlb_all() instead of local_tlb_flush_all() on rollover. > -Introduced INVALID_VMID and vCPU Sched Out logic. > -No CnP (Removed UniqueASIDAllCPUs & UniqueASIDActiveTask invariants). > -Removed UniqueVMIDPerCPU invariant for now as it looks like > because of the speculative fetching with flush_tlb_all() there > is a small window where this gets triggered. If I change the > logic back to local_flush_tlb_all(), UniqueVMIDPerCPU seems to > be fine. With my limited knowledge on TLA+ model, it is not > clear to me whether this is a problem with the above logic > or the VMID model implementation. Really appreciate any help > with the model. > The initial VMID TLA+ model is here, > https://github.com/shamiali2008/kernel-tla/tree/private-vmidalloc-v1 > > Please take a look and let me know. > > Thanks, > Shameer > > [0] > https://lore.kernel.org/kvmarm/20210721160614.GC11003@willie-the-truck/ > [1] > https://lore.kernel.org/kvmarm/20210803114034.GB30853@willie-the-truck/ > > History: > -------- > v2 --> v3 > -Dropped adding a new static key and cpufeature for retrieving > supported VMID bits. Instead, we now make use of the > kvm_arm_vmid_bits variable (patch #2). > > -Since we expect less frequent rollover in the case of VMIDs, > the TLB invalidation is now broadcasted on rollover instead > of keeping per CPU flush_pending info and issuing a local > context flush. > > -Clear active_vmids on vCPU schedule out to avoid unnecessarily > reserving the VMID space(patch #3). > > -I have kept the struct kvm_vmid as it is for now(instead of a > typedef as suggested), as we may soon add another variable to > it when we introduce Pinned KVM VMID support. > > RFCv1 --> v2 > -Dropped "pinned VMID" support for now. > -Dropped RFC tag. > RFCv1 > > https://lore.kernel.org/kvmarm/20210506165232.1969-1-shameerali.kolothu > m.thodi@xxxxxxxxxx/ > > Julien Grall (1): > KVM: arm64: Align the VMID allocation with the arm64 ASID > > Shameer Kolothum (3): > KVM: arm64: Introduce a new VMID allocator for KVM > KVM: arm64: Make VMID bits accessible outside of allocator > KVM: arm64: Make active_vmids invalid on vCPU schedule out > > arch/arm64/include/asm/kvm_host.h | 10 +- > arch/arm64/include/asm/kvm_mmu.h | 4 +- > arch/arm64/kernel/image-vars.h | 3 + > arch/arm64/kvm/Makefile | 2 +- > arch/arm64/kvm/arm.c | 106 +++----------- > arch/arm64/kvm/hyp/nvhe/mem_protect.c | 3 +- > arch/arm64/kvm/mmu.c | 1 - > arch/arm64/kvm/vmid.c | 196 > ++++++++++++++++++++++++++ > 8 files changed, 228 insertions(+), 97 deletions(-) create mode 100644 > arch/arm64/kvm/vmid.c > > -- > 2.17.1 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@xxxxxxxxxxxxxxxxxxx > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
