[PATCH] KVM: arm64: vgic: Pick EOIcount deactivations from AP-list tail

[Valentine Burley]

On Sat, 07 Mar 2026 20:11:51 +0100  Marc Zyngier <maz at kernel.org> wrote
 > Valentine reports that their guests fail to boot correctly, losing
 > interrupts, and indicates that the wrong interrupt gets deactivated.
 > 
 > What happens here is that if the maintenance interrupt is slow enough
 > to kick us out of the guest, extra interrupts can be activated from
 > the LRs. We then exit and proceed to handle EOIcount deactivations,
 > picking active interrupts from the AP list. But we start from the
 > top of the list, potentially deactivating interrupts that were in
 > the LRs, while EOIcount only denotes deactivation of interrupts that
 > are not present in an LR.
 > 
 > Solve this by tracking the last interrupt that made it in the LRs,
 > and start the EOIcount deactivation walk *after* that interrupt.
 > Since this only makes sense while the vcpu is loaded, stash this
 > in the per-CPU host state.
 > 
 > Huge thanks to Valentine for doing all the detective work and
 > providing an initial patch.
 > 
 > Fixes: 3cfd59f81e0f3 ("KVM: arm64: GICv3: Handle LR overflow when EOImode==0")
 > Fixes: 281c6c06e2a7b ("KVM: arm64: GICv2: Handle LR overflow when EOImode==0")
 > Reported-by: Valentine Burley <valentine.burley at collabora.com>
 > Signed-off-by: Marc Zyngier <maz at kernel.org>
 > Link: https://lore.kernel.org/r/20260307115955.369455-1-valentine.burley@collabora.com
 > Cc: stable at vger.kernel.org

Tested-by: Valentine Burley <valentine.burley at collabora.com>

Thanks a lot again for the quick fix!

Cheers,
Valentine