[PATCH v7 0/5] KVM: arm64: Errata management for VM Live migration

[Shameer Kolothum]

Hi,

v6-->v7
https://lore.kernel.org/kvmarm/20250205132222.55816-1-shameerali.kolothum.thodi@huawei.com/

Changes:
 -Introduced KVM_REG_ARM_VENDOR_HYP_BMAP_2 register for new hypercall
  support(patch #3)
 -Added selftest for KVM_REG_ARM_VENDOR_HYP_BMAP_2(patch #5).

This can be sanity tested by the Qemu branch here,
https://github.com/hisilicon/qemu/tree/v9.0-nv-rfcv4-vcpu-model-v2-target-cpu-errata
(branch based on Eric's/Connie's NV + custom CPU series)
Eg: to specify target impl CPUs,
-machine virt,.., x-target-impl-cpus=0xMIDR1:0xREVIDR1-0xMIDR2:REVIDR2

Please take a look and let me know your feedback.

Thanks,
Shameer

v5 --> v6
https://lore.kernel.org/kvmarm/20250124151732.6072-1-shameerali.kolothum.thodi@huawei.com/

-Addressed comments from Oliver,
 -Changed version to 32 bit to match SMCCC_VERSION
 -Don't advertise pKVM hypercalls to guests.
 -Moved hypercall invocation to kvm_guest.c
v4 --> v5
https://lore.kernel.org/kvmarm/20241218105345.73472-1-shameerali.kolothum.thodi@huawei.com/

-Addressed comments from Marc,
 -Added an hypercall to retrieve version and number of supported target
  impl CPUs.
 -Added a check for KVM hypercall services availability.
-Removed R-by tags from Connie & Sebastian as patches 2 & 4 are now
 changed a bit. Please take another look.

v3 --> v4(Minor updates)
https://lore.kernel.org/kvmarm/20241209115311.40496-1-shameerali.kolothum.thodi@huawei.com/

 -Changed MIDR/REVIDR to 64 bits based on feedback from Connie
  and Marc(Patch #3).
 -Added R-by tags from Sebastian (Thanks!).

RFC v2 --> v3
https://lore.kernel.org/kvmarm/20241024094012.29452-1-shameerali.kolothum.thodi@huawei.com/

 -Addressed comments from Oliver(Thanks!).
 -Using implementation CPUs MIDR/REVIDR when it is set for
  _midr_range() functions(Patch 1 & 3)
 -New hypercall for retrieving implementation CPUs(Patch #2).
 -Dropped RFC.

RFC v1 --> RFCv2:
https://lore.kernel.org/kvmarm/20241011075053.80540-1-shameerali.kolothum.thodi@huawei.com/
 -Introduced hypercalls to retrieve target CPUs info from user space VMM.
  see patch #1 for details.
 -Patch #2 uses the hypercall to retrieve the target CPU info if any.
 -Use the target CPUs MIDR/REVIDR in errata enablement. See patch #3.

Background from v1:

On ARM64 platforms most of the errata workarounds are based on CPU
MIDR/REVIDR values and a number of these workarounds need to be
implemented by the Guest kernel as well. This creates a problem when
Guest needs to be migrated to a platform that differs in these
MIDR/REVIDR values even if the VMM can come up with a common minimum
feature list for the Guest using the recently introduced "Writable
ID registers" support.

(This is roughly based on a discussion I had with Marc and Oliver
at KVM forum. Marc outlined his idea for a solution and this is an
attempt to implement it. Thanks to both and I take all the blame
if this is nowhere near what is intended/required)

Shameer Kolothum (5):
  arm64: Modify _midr_range() functions to read MIDR/REVIDR internally
  KVM: arm64: Introduce hypercall support for retrieving target
    implementations
  KVM: arm64: Introduce KVM_REG_ARM_VENDOR_HYP_BMAP_2
  smccc/kvm_guest: Enable errata based on implementation CPUs
  KVM: selftests: Add test for KVM_REG_ARM_VENDOR_HYP_BMAP_2

 .../virt/kvm/arm/fw-pseudo-registers.rst      | 15 ++++-
 Documentation/virt/kvm/arm/hypercalls.rst     | 59 +++++++++++++++++
 arch/arm64/include/asm/cputype.h              | 50 ++++++++++-----
 arch/arm64/include/asm/hypervisor.h           |  1 +
 arch/arm64/include/asm/kvm_host.h             |  3 +-
 arch/arm64/include/asm/mmu.h                  |  3 +-
 arch/arm64/include/uapi/asm/kvm.h             | 12 ++++
 arch/arm64/kernel/cpu_errata.c                | 37 ++++++++---
 arch/arm64/kernel/cpufeature.c                |  8 ++-
 arch/arm64/kernel/image-vars.h                |  2 +
 arch/arm64/kernel/proton-pack.c               | 17 +++--
 arch/arm64/kvm/hypercalls.c                   | 13 ++++
 arch/arm64/kvm/vgic/vgic-v3.c                 |  2 +-
 drivers/clocksource/arm_arch_timer.c          |  2 +-
 drivers/firmware/smccc/kvm_guest.c            | 63 +++++++++++++++++++
 include/linux/arm-smccc.h                     | 15 +++++
 tools/arch/arm64/include/uapi/asm/kvm.h       | 12 ++++
 .../selftests/kvm/arm64/get-reg-list.c        |  1 +
 .../testing/selftests/kvm/arm64/hypercalls.c  | 46 +++++++++++---
 19 files changed, 308 insertions(+), 53 deletions(-)

-- 
2.47.0