[v3,0/3] KVM: arm64: Errata management for VM Live migration

Message

Shameerali Kolothum Thodi Dec. 9, 2024, 11:53 a.m. UTC

Hi,

Changes from RFC v2[1]:

 -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.

Sanity tested on a HiSilicon ARM64 platform using a hacked Qemu that can
handle the above hypercall.

Thanks,
Shameer
[1] https://lore.kernel.org/kvmarm/[e-mail]/

Changes from RFC v1:
 https://lore.kernel.org/kvmarm/[e-mail]/
 -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 (3):
  arm64: Modify _midr_range() functions to read MIDR/REVIDR internally
  KVM: arm64: Introduce hypercall support for retrieving target
    implementations
  arm64: paravirt: Enable errata based on implementation CPUs

 Documentation/virt/kvm/arm/hypercalls.rst | 30 +++++++++++++
 arch/arm64/include/asm/cputype.h          | 51 ++++++++++++++++-------
 arch/arm64/include/asm/mmu.h              |  3 +-
 arch/arm64/include/asm/paravirt.h         |  3 ++
 arch/arm64/kernel/cpu_errata.c            | 37 +++++++++++-----
 arch/arm64/kernel/cpufeature.c            |  8 ++--
 arch/arm64/kernel/image-vars.h            |  2 +
 arch/arm64/kernel/paravirt.c              | 31 ++++++++++++++
 arch/arm64/kernel/proton-pack.c           | 17 ++++----
 arch/arm64/kvm/vgic/vgic-v3.c             |  2 +-
 drivers/clocksource/arm_arch_timer.c      |  2 +-
 include/linux/arm-smccc.h                 |  7 ++++
 12 files changed, 152 insertions(+), 41 deletions(-)