This series adds support for using the Arm Memory Tagging Extensions (MTE) in a KVM guest. I realise there are still open questions[1] around the performance of this series (the 'big lock', tag_sync_lock, introduced in the first patch). But there should be no impact on non-MTE workloads and until we get real MTE-enabled hardware it's hard to know whether there is a need for something more sophisticated or not. Peter Collingbourne's patch[3] to clear the tags at page allocation time should hide more of the impact for non-VM cases. So the remaining concern is around VM startup which could be effectively serialised through the lock. Changes since v14[2]: * Dropped "Handle MTE tags zeroing" patch in favour of Peter's similar patch[3] (now in arm64 tree). * Improved documentation following Catalin's review. [1]: https://lore.kernel.org/r/874ke7z3ng.wl-maz%40kernel.org [2]: https://lore.kernel.org/r/20210607110816.25762-1-steven.price@xxxxxxx/ [3]: https://lore.kernel.org/r/20210602235230.3928842-4-pcc@xxxxxxxxxx/ Steven Price (7): arm64: mte: Handle race when synchronising tags arm64: mte: Sync tags for pages where PTE is untagged KVM: arm64: Introduce MTE VM feature KVM: arm64: Save/restore MTE registers KVM: arm64: Expose KVM_ARM_CAP_MTE KVM: arm64: ioctl to fetch/store tags in a guest KVM: arm64: Document MTE capability and ioctl Documentation/virt/kvm/api.rst | 57 +++++++++++++++ arch/arm64/include/asm/kvm_arm.h | 3 +- arch/arm64/include/asm/kvm_emulate.h | 3 + arch/arm64/include/asm/kvm_host.h | 12 ++++ arch/arm64/include/asm/kvm_mte.h | 66 +++++++++++++++++ arch/arm64/include/asm/mte-def.h | 1 + arch/arm64/include/asm/mte.h | 8 ++- arch/arm64/include/asm/pgtable.h | 22 +++++- arch/arm64/include/asm/sysreg.h | 3 +- arch/arm64/include/uapi/asm/kvm.h | 11 +++ arch/arm64/kernel/asm-offsets.c | 2 + arch/arm64/kernel/mte.c | 54 ++++++++++++-- arch/arm64/kvm/arm.c | 16 +++++ arch/arm64/kvm/guest.c | 82 ++++++++++++++++++++++ arch/arm64/kvm/hyp/entry.S | 7 ++ arch/arm64/kvm/hyp/exception.c | 3 +- arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h | 21 ++++++ arch/arm64/kvm/mmu.c | 42 ++++++++++- arch/arm64/kvm/reset.c | 3 +- arch/arm64/kvm/sys_regs.c | 32 +++++++-- include/uapi/linux/kvm.h | 2 + 21 files changed, 429 insertions(+), 21 deletions(-) create mode 100644 arch/arm64/include/asm/kvm_mte.h -- 2.20.1 _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
