[PATCH v2 0/2] arm: cpu: Add optional CMOs by VA

Ying-Chun Liu (PaulLiu) paul.liu at linaro.org
Wed Feb 8 21:54:26 CET 2023

Exposing set/way cache maintenance to a virtual machine is unsafe, not
least because the instructions are not permission-checked but also
because they are not broadcast between CPUs. Consequently, KVM traps and
emulates such maintenance in the host kernel using by-VA operations and
looping over the stage-2 page-tables. However, when running under
protected KVM, these instructions are not able to be emulated and will
instead result in an exception being delivered to the guest.

Introduce CONFIG_CMO_BY_VA_ONLY so that virtual platforms can select
this option and perform by-VA cache maintenance instead of using the
set/way instructions.

Marc Zyngier (1):
  arm: cpu: Add optional CMOs by VA

Pierre-Clément Tosi (1):
  arm64: Initialize TLB memory if CMO_BY_VA_ONLY

v2: Fix the Signed-off-by list.

 arch/arm/cpu/armv8/Kconfig    |  4 ++
 arch/arm/cpu/armv8/cache.S    | 50 +++++++++++++-----
 arch/arm/cpu/armv8/cache_v8.c | 97 ++++++++++++++++++++++++++++++++++-
 arch/arm/cpu/armv8/cpu.c      | 30 +++++++----
 arch/arm/lib/cache.c          |  9 ++++
 5 files changed, 164 insertions(+), 26 deletions(-)


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