It appears that there is firmware out there that advertise GICv2
compatibility on GICv3, despite the CPUs not being able to actually do
it. That's a bummer, and at best creates unexpected behaviours for the
users. At worse, it will crash the machine. Awesome!
In order to mitigate this issue, try and validate whether we can
actually flip the CPU into supporting MMIO accesses instead of system
registers. If we can't, ignore the compatibility information and
shout. It's not completely foolproof, but it should cover the existing
broken platforms...
The workaround is much bigger than Shameer's initial proposal, but
that's because I wanted to keep it localised to KVM, and not spread
the horror at every level (after all, only KVM is concerned with v2
compat).
Marc Zyngier (2):
KVM: arm64: Rename __vgic_v3_get_ich_vtr_el2() to
__vgic_v3_get_gic_config()
KVM: arm64: Workaround firmware wrongly advertising GICv2-on-v3
compatibility
arch/arm64/include/asm/kvm_asm.h | 4 +--
arch/arm64/kvm/hyp/nvhe/hyp-main.c | 6 ++---
arch/arm64/kvm/hyp/vgic-v3-sr.c | 39 ++++++++++++++++++++++++++++--
arch/arm64/kvm/vgic/vgic-v3.c | 12 ++++++---
4 files changed, 51 insertions(+), 10 deletions(-)
--
2.29.2
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