Subject: [PATCH 0/3] KVM: arm64: FEAT_{S1POE,ATS1A} support fixes

From: Marc Zyngier <[email-masked]>
Date: Tue, 2 Jun 2026 16:54:26 +0100

Whilst working on a slightly unrelated feature (FEAT_NV3), I found out
that an L2 guest wouldn't boot if the host was exposed to FEAT_S1POE.

Upon investigation (and hours wasted in a SW model), it became
apparent that while the AT S1E1A code was ready for action, it had
never been fully plugged in (blame the usual suspect...).

This resulted in an extremely odd failure mode, with an L2 being
unable to make forward progress, but KVM at L1 not taking the hint
that something was really wrong. Additionally, an embarrassing typo
was spotted in the CPTR_EL2 handling.

With this in, FEAT_S1POE no longer breaks our NV guests.

Marc Zyngier (3):
  KVM: arm64: Key CPTR_EL2.E0POE propagation on FEAT_S1POE
  KVM: arm64: Wire AT S1E1A in the system instruction handling table
  arm64: cpufeature: Expose ID_AA64ISAR2_EL1.ATS1A to KVM

 arch/arm64/kernel/cpufeature.c          | 1 +
 arch/arm64/kvm/hyp/include/hyp/switch.h | 2 +-
 arch/arm64/kvm/sys_regs.c               | 1 +
 3 files changed, 3 insertions(+), 1 deletion(-)

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2.47.3