linux-kernel - [PATCH] KVM: arm64: vgic-v3: Trap all if no in-kernel irqchip

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Message-ID: <20251021094358.1963807-1-sascha.bischoff@arm.com>
Date: Tue, 21 Oct 2025 09:44:09 +0000
From: Sascha Bischoff <Sascha.Bischoff@....com>
To: "linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "kvmarm@...ts.linux.dev"
	<kvmarm@...ts.linux.dev>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "kvm@...r.kernel.org" <kvm@...r.kernel.org>
CC: nd <nd@....com>, "maz@...nel.org" <maz@...nel.org>, "broonie@...nel.org"
	<broonie@...nel.org>, "oliver.upton@...ux.dev" <oliver.upton@...ux.dev>, Joey
 Gouly <Joey.Gouly@....com>, Suzuki Poulose <Suzuki.Poulose@....com>,
	"yuzenghui@...wei.com" <yuzenghui@...wei.com>
Subject: [PATCH] KVM: arm64: vgic-v3: Trap all if no in-kernel irqchip

If there is no in-kernel irqchip for a GICv3 host set all of the trap
bits to block all accesses. This fixes the no-vgic-v3 selftest again.

Fixes: 3193287ddffb ("KVM: arm64: gic-v3: Only set ICH_HCR traps for v2-on-v3 or v3 guests")
Reported-by: Mark Brown <broonie@...nel.org>
Closes: https://lore.kernel.org/all/23072856-6b8c-41e2-93d1-ea8a240a7079@sirena.org.uk
Signed-off-by: Sascha Bischoff <sascha.bischoff@....com>
---
 arch/arm64/kvm/vgic/vgic-v3.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/vgic/vgic-v3.c b/arch/arm64/kvm/vgic/vgic-v3.c
index 6fbb4b099855..2f75ef14d339 100644
--- a/arch/arm64/kvm/vgic/vgic-v3.c
+++ b/arch/arm64/kvm/vgic/vgic-v3.c
@@ -301,7 +301,8 @@ void vcpu_set_ich_hcr(struct kvm_vcpu *vcpu)
 		return;
 
 	/* Hide GICv3 sysreg if necessary */
-	if (vcpu->kvm->arch.vgic.vgic_model == KVM_DEV_TYPE_ARM_VGIC_V2) {
+	if (vcpu->kvm->arch.vgic.vgic_model == KVM_DEV_TYPE_ARM_VGIC_V2 ||
+	    !irqchip_in_kernel(vcpu->kvm)) {
 		vgic_v3->vgic_hcr |= (ICH_HCR_EL2_TALL0 | ICH_HCR_EL2_TALL1 |
 				      ICH_HCR_EL2_TC);
 		return;
-- 
2.34.1