* [PATCH] KVM: arm64: gic: Check for vGICv3 when clearing TWI
@ 2026-01-06 16:52 Sascha Bischoff
2026-01-06 18:13 ` Marc Zyngier
2026-01-10 10:22 ` Oliver Upton
0 siblings, 2 replies; 3+ messages in thread
From: Sascha Bischoff @ 2026-01-06 16:52 UTC (permalink / raw)
To: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
kvm@vger.kernel.org
Cc: nd, maz@kernel.org, oliver.upton@linux.dev, Joey Gouly,
Suzuki Poulose, yuzenghui@huawei.com
Explicitly check for the vgic being v3 when disabling TWI. Failure to
check this can result in using the wrong view of the vgic CPU IF union
causing undesirable/unexpected behaviour.
Signed-off-by: Sascha Bischoff <sascha.bischoff@arm.com>
---
arch/arm64/kvm/arm.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 4f80da0c0d1de..620a465248d1b 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -569,6 +569,7 @@ static bool kvm_vcpu_should_clear_twi(struct kvm_vcpu *vcpu)
return kvm_wfi_trap_policy == KVM_WFX_NOTRAP;
return single_task_running() &&
+ vcpu->kvm->arch.vgic.vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3 &&
(atomic_read(&vcpu->arch.vgic_cpu.vgic_v3.its_vpe.vlpi_count) ||
vcpu->kvm->arch.vgic.nassgireq);
}
--
2.34.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] KVM: arm64: gic: Check for vGICv3 when clearing TWI
2026-01-06 16:52 [PATCH] KVM: arm64: gic: Check for vGICv3 when clearing TWI Sascha Bischoff
@ 2026-01-06 18:13 ` Marc Zyngier
2026-01-10 10:22 ` Oliver Upton
1 sibling, 0 replies; 3+ messages in thread
From: Marc Zyngier @ 2026-01-06 18:13 UTC (permalink / raw)
To: Sascha Bischoff
Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
kvm@vger.kernel.org, nd, oliver.upton@linux.dev, Joey Gouly,
Suzuki Poulose, yuzenghui@huawei.com
On Tue, 06 Jan 2026 16:52:10 +0000,
Sascha Bischoff <Sascha.Bischoff@arm.com> wrote:
>
> Explicitly check for the vgic being v3 when disabling TWI. Failure to
> check this can result in using the wrong view of the vgic CPU IF union
> causing undesirable/unexpected behaviour.
>
> Signed-off-by: Sascha Bischoff <sascha.bischoff@arm.com>
> ---
> arch/arm64/kvm/arm.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index 4f80da0c0d1de..620a465248d1b 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -569,6 +569,7 @@ static bool kvm_vcpu_should_clear_twi(struct kvm_vcpu *vcpu)
> return kvm_wfi_trap_policy == KVM_WFX_NOTRAP;
>
> return single_task_running() &&
> + vcpu->kvm->arch.vgic.vgic_model == KVM_DEV_TYPE_ARM_VGIC_V3 &&
> (atomic_read(&vcpu->arch.vgic_cpu.vgic_v3.its_vpe.vlpi_count) ||
> vcpu->kvm->arch.vgic.nassgireq);
> }
Nice one. Wonder how many other similar cases we have... :-/
Reviewed-by: Marc Zyngier <maz@kernel.org>
M.
--
Without deviation from the norm, progress is not possible.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] KVM: arm64: gic: Check for vGICv3 when clearing TWI
2026-01-06 16:52 [PATCH] KVM: arm64: gic: Check for vGICv3 when clearing TWI Sascha Bischoff
2026-01-06 18:13 ` Marc Zyngier
@ 2026-01-10 10:22 ` Oliver Upton
1 sibling, 0 replies; 3+ messages in thread
From: Oliver Upton @ 2026-01-10 10:22 UTC (permalink / raw)
To: linux-arm-kernel, kvmarm, kvm, Sascha Bischoff
Cc: Oliver Upton, nd, maz, Joey Gouly, Suzuki Poulose, yuzenghui
On Tue, 06 Jan 2026 16:52:10 +0000, Sascha Bischoff wrote:
> Explicitly check for the vgic being v3 when disabling TWI. Failure to
> check this can result in using the wrong view of the vgic CPU IF union
> causing undesirable/unexpected behaviour.
>
>
Applied to fixes, thanks!
[1/1] KVM: arm64: gic: Check for vGICv3 when clearing TWI
https://git.kernel.org/kvmarm/kvmarm/c/5e8b511c39f3
--
Best,
Oliver
^ permalink raw reply [flat|nested] 3+ messages in thread
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2026-01-06 16:52 [PATCH] KVM: arm64: gic: Check for vGICv3 when clearing TWI Sascha Bischoff
2026-01-06 18:13 ` Marc Zyngier
2026-01-10 10:22 ` Oliver Upton
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