KVM: arm64: Merge guest's HCRX_EL2 using NV_HCRX_GUEST_EXCLUDE

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The way we merge the guest-provided HCRX_EL2 value with the host's
is bonkers. We try to make it look like the FGT registers by using
positive and negative polarities for traps, but most of these bits
are not strictly about trapping, as they actively change the way
some architectural state is managed.

It would be far better to deal with these bits like we do for
HCR_EL2, by enumerating the list of bits we don't allow the guest
to override. This is simplified by the fact that HCRX_EL2 only
affects EL1, and not EL2.

Re-jig the HCRX_EL2 handling with a macro that list the bits excluded
from the merge (TMEA, PTTWI, EnIDCP128).

Reviewed-by: Yuan Yao <yaoyuan@linux.alibaba.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Joey Gouly <joey.gouly@arm.com>
Link: https://patch.msgid.link/20260730071022.296811-4-maz@kernel.org
Signed-off-by: Oliver Upton <oupton@kernel.org>

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Marc Zyngier 2026-07-30 08:09:56 +01:00 • committed by Oliver Upton

parent 1441f717ab

commit 4422d8b750

1 changed files with 20 additions and 2 deletions

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arch/arm64/kvm/hyp/include/hyp/switch.h

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