[v16,0/7] MTE support for KVM guest

Message

Steven Price June 18, 2021, 1:28 p.m. UTC

This series adds support for using the Arm Memory Tagging Extensions
(MTE) in a KVM guest.

This time with less BKL but hopefully no new races!

Changes since v15[1]:

 - Prevent VM_SHARED mappings with an MTE-enabled VM.

 - Dropped the mte_prepare_page_tags() function, sanitise_mte_tags() now
   does the PG_mte_tagged dance without extra locks.

 - Added a comment to sanitise_mte_tags() explaining why the apparent
   race with the test/set of page->flags is safe.

 - Added a sentence to kvm/api.rst explaining that VM_SHARED is not
   permitted when used with MTE in a guest.

 - Dropped the Reviewed-by tags on patches 3 and 7 due to the changes.

[1] https://lore.kernel.org/r/20210614090525.4338-1-steven.price%40arm.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             | 61 ++++++++++++++++
 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               |  4 +-
 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                    | 37 ++++++++--
 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                       | 62 +++++++++++++++-
 arch/arm64/kvm/reset.c                     |  3 +-
 arch/arm64/kvm/sys_regs.c                  | 32 +++++++--
 include/uapi/linux/kvm.h                   |  2 +
 21 files changed, 432 insertions(+), 21 deletions(-)
 create mode 100644 arch/arm64/include/asm/kvm_mte.h