[PATCH v2 29/45] KVM: arm64: GICv3: Set ICH_HCR_EL2.TDIR when interrupts overflow LR capacity

[Fuad Tabba]

Hi Marc,

On Sun, 9 Nov 2025 at 17:17, Marc Zyngier <maz at kernel.org> wrote:
>
> Now that we are ready to handle deactivation through ICV_DIR_EL1,
> set the trap bit if we have active interrupts outside of the LRs.
>
> Signed-off-by: Marc Zyngier <maz at kernel.org>
> ---
>  arch/arm64/kvm/vgic/vgic-v3.c | 7 +++++++
>  1 file changed, 7 insertions(+)
>
> diff --git a/arch/arm64/kvm/vgic/vgic-v3.c b/arch/arm64/kvm/vgic/vgic-v3.c
> index 1026031f22ff9..26e17ed057f00 100644
> --- a/arch/arm64/kvm/vgic/vgic-v3.c
> +++ b/arch/arm64/kvm/vgic/vgic-v3.c
> @@ -42,6 +42,13 @@ void vgic_v3_configure_hcr(struct kvm_vcpu *vcpu,
>                 ICH_HCR_EL2_VGrp0DIE : ICH_HCR_EL2_VGrp0EIE;
>         cpuif->vgic_hcr |= (cpuif->vgic_vmcr & ICH_VMCR_ENG1_MASK) ?
>                 ICH_HCR_EL2_VGrp1DIE : ICH_HCR_EL2_VGrp1EIE;
> +
> +       /*
> +        * Note that we set the trap irrespective of EOIMode, as that
> +        * can change behind our back without any warning...
> +        */
> +       if (irqs_active_outside_lrs(als))
> +               cpuif->vgic_hcr |= ICH_HCR_EL2_TDIR;
>  }

I just tested these patches as they are on kvmarm/next
2ea7215187c5759fc5d277280e3095b350ca6a50 ("Merge branch
'kvm-arm64/vgic-lr-overflow' into kvmarm/next"), without any
additional pKVM patches. I tried running it with pKVM (non-protected)
and with just plain nVHE. In both cases, I get a trap to EL2 (0x18)
when booting a non-protected guest, which triggers a bug in
handle_trap() arch/arm64/kvm/hyp/nvhe/hyp-main.c:706

This trap is happening because of setting this particular trap (TDIR).
Just removing this trap from vgic_v3_configure_hcr() from the ToT on
kvmarm/next boots fine.

I'm running this on QEMU with '-machine virt,gic-version=3 -cpu max'
and the kernel with 'kvm-arm.mode=protected' and with
'kvm-arm.mode=nvhe'.

Let me know if you need any more info or help testing.

Cheers,
/fuad


>  static bool lr_signals_eoi_mi(u64 lr_val)
> --
> 2.47.3
>
>