[PATCH v4 16/49] KVM: arm64: GICv2: Decouple GICH_HCR programming from LRs being loaded

Marc Zyngier
2025-11-20T17:25:59Z

Not programming GICH_HCR while no LRs are populated is a bit
of an issue, as we otherwise don't see any maintenance interrupt
when the guest interacts with the LRs.

Decouple the two and always program the control register, even when
we don't have to touch the LRs.

This is very similar to what we are already doing for GICv3.

Tested-by: Fuad Tabba <tabba@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
---
arch/arm64/kvm/vgic/vgic-v2.c | 28 ++++++++++++++--------------
1 file changed, 14 insertions(+), 14 deletions(-)

diff --git a/arch/arm64/kvm/vgic/vgic-v2.c b/arch/arm64/kvm/vgic/vgic-v2.c
index 5cfbe58983428..a0d803c5b08ae 100644
--- a/arch/arm64/kvm/vgic/vgic-v2.c
+++ b/arch/arm64/kvm/vgic/vgic-v2.c
@@ -430,22 +430,25 @@ static void save_lrs(struct kvm_vcpu *vcpu, void __iomem *base)

void vgic_v2_save_state(struct kvm_vcpu *vcpu)
{
+ struct vgic_v2_cpu_if *cpu_if = &vcpu->arch.vgic_cpu.vgic_v2;
void __iomem *base = kvm_vgic_global_state.vctrl_base;
u64 used_lrs = vcpu->arch.vgic_cpu.vgic_v2.used_lrs;

if (!base)
return;

- if (used_lrs) {
- if (vcpu->arch.vgic_cpu.vgic_v2.vgic_hcr & GICH_HCR_LRENPIE) {
- u32 val = readl_relaxed(base + GICH_HCR);

- vcpu->arch.vgic_cpu.vgic_v2.vgic_hcr &= ~GICH_HCR_EOICOUNT;
- vcpu->arch.vgic_cpu.vgic_v2.vgic_hcr |= val & GICH_HCR_EOICOUNT;
- }
+ if (used_lrs)
save_lrs(vcpu, base);
- writel_relaxed(0, base + GICH_HCR);
+
+ if (cpu_if->vgic_hcr & GICH_HCR_LRENPIE) {
+ u32 val = readl_relaxed(base + GICH_HCR);
+
+ cpu_if->vgic_hcr &= ~GICH_HCR_EOICOUNT;
+ cpu_if->vgic_hcr |= val & GICH_HCR_EOICOUNT;
}
+
+ writel_relaxed(0, base + GICH_HCR);
}

void vgic_v2_restore_state(struct kvm_vcpu *vcpu)
@@ -458,13 +461,10 @@ void vgic_v2_restore_state(struct kvm_vcpu *vcpu)
if (!base)
return;

- if (used_lrs) {
- writel_relaxed(cpu_if->vgic_hcr, base + GICH_HCR);
- for (i = 0; i < used_lrs; i++) {
- writel_relaxed(cpu_if->vgic_lr[i],
- base + GICH_LR0 + (i * 4));
- }
- }
+ writel_relaxed(cpu_if->vgic_hcr, base + GICH_HCR);
+
+ for (i = 0; i < used_lrs; i++)
+ writel_relaxed(cpu_if->vgic_lr[i], base + GICH_LR0 + (i * 4));
}

void vgic_v2_load(struct kvm_vcpu *vcpu)
--
2.47.3