KVM: arm64: Add helper for swapping guest descriptor

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Implementing FEAT_HAFDBS in KVM's software PTWs requires the ability to
CAS a descriptor to update the in-memory value. Add an accessor to do
exactly that, coping with the fact that guest descriptors are in user
memory (duh).

While FEAT_LSE required on any system that implements NV, KVM now uses
the stage-1 PTW for non-nested use cases meaning an LL/SC implementation
is necessary as well.

Reviewed-by: Marc Zyngier <maz@kernel.org>
Tested-by: Marc Zyngier <maz@kernel.org>
Link: https://msgid.link/20251124190158.177318-11-oupton@kernel.org
Signed-off-by: Oliver Upton <oupton@kernel.org>

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Oliver Upton 2025-11-24 11:01:52 -08:00

parent 590e694820

commit f6927b41d5

2 changed files with 89 additions and 0 deletions

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arch/arm64/include/asm/kvm_nested.h

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87

arch/arm64/kvm/at.c

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