[PATCH v15 0/7] MTE support for KVM guest

[Steven Price]

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]: 20210607110816.25762-1-steven.price@arm.com/">https://lore.kernel.org/r/20210607110816.25762-1-steven.price@arm.com/
[3]: https://lore.kernel.org/r/20210602235230.3928842-4-pcc@google.com/

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