[PATCH 0/3] KVM: arm64: Work around Ampere1 erratum AC03_CPU_38

[Oliver Upton <oliver.upton@linux.dev>]

Hi folks,

Small series to work around a CPU erratum on AmpereOne. While the
implementation does not advertise support for FEAT_HAFDBS (due to
another erratum), the associated control bits do not have RES0 behavior
as required by the architecture.

Usage of HAFDBS at stage-1 is unaffected, since HA and HD are only
enabled on implementations that advertise the feature. However, KVM
relies on HA having RES0 semantics if the feature isn't implemented. The
end result is that KVM enables a broken hardware access flag
implementation that could lead to correctness issues.

Applies to 6.4-rc1. Tested with access_tracking_perf_test, verifying
that KVM is indeed taking Access Flag faults.

Oliver Upton (3):
  arm64: errata: Mitigate Ampere1 erratum AC03_CPU_38 at stage-2
  KVM: arm64: Refactor HFGxTR configuration into separate helpers
  KVM: arm64: Prevent guests from enabling HA/HD on Ampere1

 Documentation/arm64/silicon-errata.rst  |  3 +
 arch/arm64/Kconfig                      | 17 +++++
 arch/arm64/kernel/cpu_errata.c          |  7 ++
 arch/arm64/kvm/hyp/include/hyp/switch.h | 99 ++++++++++++++++++++-----
 arch/arm64/kvm/hyp/pgtable.c            | 14 +++-
 arch/arm64/tools/cpucaps                |  1 +
 6 files changed, 120 insertions(+), 21 deletions(-)


base-commit: ac9a78681b921877518763ba0e89202254349d1b
-- 
2.41.0.162.gfafddb0af9-goog