[PATCH v7 0/3] MTE support for KVM guest

[Steven Price]

After chasing down a bug[1] with MTE assisted KASAN and KVM, I've now
been able to rebase on v5.11-rc1 and test the combination of
KVM-with-MTE and KASAN.

For anyone new to this series, or simply pretending 2020 didn't happen,
this series adds support for Arm's Memory Tagging Extension (MTE) to KVM,
allowing KVM guests to make use of it. The first patch adds definitions
for the new registers and saves/restores them as necessary. The second
adds a new VM feature which allows the guest access to MTE.

The third patch is new and RFC for now. It adds a new ioctl allowing a
VMM to easily read/write the tags in the guest's memory even if the
memory isn't mapped with PROT_MTE in userspace. I'd particularly welcome
feedback on this new ABI.

Changes since v6[2]:
 * Moved the save/restore of RGSR_EL1, GCR_EL1 and TFSRE0_EL into asm
 * Correctly set TCO when injecting an exception to an MTE-enabled guest
 * Rebased on v5.11-rc1
 * RFC patch for new MTE tag copy ioctl

[1] https://lore.kernel.org/r/20210108161254.53674-1-steven.price@arm.com
[2] https://lore.kernel.org/r/20201127152113.13099-1-steven.price@arm.com

Steven Price (3):
  arm64: kvm: Save/restore MTE registers
  arm64: kvm: Introduce MTE VCPU feature
  KVM: arm64: ioctl to fetch/store tags in a guest

 arch/arm64/include/asm/kvm_emulate.h       |  3 +
 arch/arm64/include/asm/kvm_host.h          |  7 ++
 arch/arm64/include/asm/kvm_mte.h           | 74 ++++++++++++++++++++++
 arch/arm64/include/asm/pgtable.h           |  2 +-
 arch/arm64/include/asm/sysreg.h            |  3 +-
 arch/arm64/include/uapi/asm/kvm.h          | 13 ++++
 arch/arm64/kernel/asm-offsets.c            |  3 +
 arch/arm64/kernel/mte.c                    | 36 +++++++----
 arch/arm64/kvm/arm.c                       | 68 ++++++++++++++++++++
 arch/arm64/kvm/hyp/entry.S                 |  7 ++
 arch/arm64/kvm/hyp/exception.c             |  3 +-
 arch/arm64/kvm/hyp/include/hyp/sysreg-sr.h |  4 ++
 arch/arm64/kvm/mmu.c                       | 16 +++++
 arch/arm64/kvm/sys_regs.c                  | 20 ++++--
 include/uapi/linux/kvm.h                   |  2 +
 15 files changed, 239 insertions(+), 22 deletions(-)
 create mode 100644 arch/arm64/include/asm/kvm_mte.h

-- 
2.20.1