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KVM: arm64: GICv3: Detect and work around the lack of ICV_DIR_EL1 trapping

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A long time ago, an unsuspecting architect forgot to add a trap
bit for ICV_DIR_EL1 in ICH_HCR_EL2. Which was unfortunate, but
what's a bit of spec between friends? Thankfully, this was fixed
in a later revision, and ARM "deprecates" the lack of trapping
ability.

Unfortuantely, a few (billion) CPUs went out with that defect,
anything ARMv8.0 from ARM, give or take. And on these CPUs,
you can't trap DIR on its own, full stop.

As the next best thing, we can trap everything in the common group,
which is a tad expensive, but hey ho, that's what you get. You can
otherwise recycle the HW in the neaby bin.

Tested-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Tested-by: Mark Brown <broonie@kernel.org>
Link: https://msgid.link/20251120172540.2267180-7-maz@kernel.org
Signed-off-by: Oliver Upton <oupton@kernel.org>
This commit is contained in:
Marc Zyngier 2025-11-20 17:24:56 +00:00 • committed by Oliver Upton
commit 2a28810cbb
5 changed files with 67 additions and 1 deletions
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