[v2,0/5] arm64: KVM: Add workaround for errata 1319367 and 1319537

Message

Marc Zyngier Oct. 19, 2019, 9:55 a.m. UTC

Similarily to erratum 1165522 that affects Cortex-A76, our good old
friends A57 and A72 respectively suffer from errata 1319537 and
1319367, potentially resulting in TLB corruption if the CPU speculates
an AT instruction while switching guests.

The fix is slightly more involved since we don't have VHE to help us
here, but the idea is the same: When switching a guest in, we must
prevent any speculated AT from being able to parse the page tables
until S2 is up and running. Only at this stage can we allow AT to take
place.

For this, we always restore the guest sysregs first, except for its
SCTLR and TCR registers, which must be set with SCTLR.M=1 and
TCR.EPD{0,1} = {1, 1}, effectively disabling the PTW and TLB
allocation. Once S2 is setup, we restore the guest's SCTLR and
TCR. Similar things must be done on TLB invalidation... Fun.

This has been tested on an AMD Seattle box.

* From v1 [1]:
  - Reworked patch 4 to close the speculation window on the host
  - Fixed comments
  - Collected ABs/RBs

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

Marc Zyngier (5):
  arm64: Add ARM64_WORKAROUND_1319367 for all A57 and A72 versions
  arm64: KVM: Reorder system register restoration and stage-2 activation
  arm64: KVM: Disable EL1 PTW when invalidating S2 TLBs
  arm64: KVM: Prevent speculative S1 PTW when restoring vcpu context
  arm64: Enable and document ARM errata 1319367 and 1319537

 Documentation/arm64/silicon-errata.rst |  4 +++
 arch/arm64/Kconfig                     | 10 ++++++
 arch/arm64/include/asm/cpucaps.h       |  3 +-
 arch/arm64/kernel/cpu_errata.c         | 13 +++++--
 arch/arm64/kvm/hyp/switch.c            | 48 ++++++++++++++++++++++----
 arch/arm64/kvm/hyp/sysreg-sr.c         | 35 +++++++++++++++++--
 arch/arm64/kvm/hyp/tlb.c               | 23 ++++++++++++
 7 files changed, 124 insertions(+), 12 deletions(-)