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KVM: arm64: at: Update AF on software walk only if VM has FEAT_HAFDBS

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A guest can write 1 to TCR_ELx.HA, making the KVM software walker update
the access flag in a table descriptor even if FEAT_HAFDBS is not present.
Avoid this by making wi->ha depend on FEAT_HAFDBS being enabled in the VM,
similar to how the software walker treats FEAT_HPDS.

This is not needed for VTCR_EL2.HA, since a guest will always write to
the in-memory copy of the register, where the HA bit is masked (set to
0) by KVM if the VM doesn't have FEAT_HAFDBS.

Fixes: c59ca4b5b0c3 ("KVM: arm64: Implement HW access flag management in stage-1 SW PTW")
Signed-off-by: Alexandru Elisei <alexandru.elisei@arm.com>
Link: https://msgid.link/20251128100946.74210-5-alexandru.elisei@arm.com
Signed-off-by: Oliver Upton <oupton@kernel.org>
This commit is contained in:
Alexandru Elisei
2025-11-28 10:09:46 +00:00
committed by Oliver Upton
parent e88d60c0aa
commit d52aca1635
1 changed files with 2 additions and 1 deletions
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3
arch/arm64/kvm/at.c
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@@ -346,7 +346,8 @@ static int setup_s1_walk(struct kvm_vcpu *vcpu, struct s1_walk_info *wi,
wi->baddr &= GENMASK_ULL(wi->max_oa_bits - 1, x);
wi->ha = (wi->regime == TR_EL2 ?
wi->ha = kvm_has_feat(vcpu->kvm, ID_AA64MMFR1_EL1, HAFDBS, AF);
wi->ha &= (wi->regime == TR_EL2 ?
FIELD_GET(TCR_EL2_HA, tcr) :
FIELD_GET(TCR_HA, tcr));