[PATCH v4 39/49] KVM: arm64: GICv2: Always trap GICV_DIR register

Marc Zyngier
2025-11-20T17:26:05Z

Since we can't decide to trap the DIR register on a per-vcpu basis,
always trap the second page of the GIC CPU interface. Yes, this is
costly. On the bright side, no sane SW should use EOImode==1 on
GICv2...

Tested-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
arch/arm64/kvm/hyp/vgic-v2-cpuif-proxy.c | 4 ++++
arch/arm64/kvm/vgic/vgic-v2.c | 2 +-
2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/hyp/vgic-v2-cpuif-proxy.c b/arch/arm64/kvm/hyp/vgic-v2-cpuif-proxy.c
index 78579b31a4205..5fd99763b54de 100644
--- a/arch/arm64/kvm/hyp/vgic-v2-cpuif-proxy.c
+++ b/arch/arm64/kvm/hyp/vgic-v2-cpuif-proxy.c
@@ -63,6 +63,10 @@ int __vgic_v2_perform_cpuif_access(struct kvm_vcpu *vcpu)
return -1;
}

+ /* Handle deactivation as a normal exit */
+ if ((fault_ipa - vgic->vgic_cpu_base) >= GIC_CPU_DEACTIVATE)
+ return 0;
+
rd = kvm_vcpu_dabt_get_rd(vcpu);
addr = kvm_vgic_global_state.vcpu_hyp_va;
addr += fault_ipa - vgic->vgic_cpu_base;
diff --git a/arch/arm64/kvm/vgic/vgic-v2.c b/arch/arm64/kvm/vgic/vgic-v2.c
index bc52d44a573d5..585491fbda807 100644
--- a/arch/arm64/kvm/vgic/vgic-v2.c
+++ b/arch/arm64/kvm/vgic/vgic-v2.c
@@ -457,7 +457,7 @@ int vgic_v2_map_resources(struct kvm *kvm)
if (!static_branch_unlikely(&vgic_v2_cpuif_trap)) {
ret = kvm_phys_addr_ioremap(kvm, dist->vgic_cpu_base,
kvm_vgic_global_state.vcpu_base,
- KVM_VGIC_V2_CPU_SIZE, true);
+ KVM_VGIC_V2_CPU_SIZE - SZ_4K, true);
if (ret) {
kvm_err("Unable to remap VGIC CPU to VCPU\n");
return ret;
--
2.47.3