KVM: arm/arm64: vgic: Get rid of unnecessary process_maintenance operation

Since we always read back the LRs that we wrote to the guest and the
MISR and EISR registers simply provide a summary of the configuration of
the bits in the LRs, there is really no need to read back those status
registers and process them.  We might as well just signal the
notifyfd when folding the LR state and save some cycles in the process.
We now clear the underflow bit in the fold_lr_state functions as we only
need to clear this bit if we had used all the LRs, so this is as good a
place as any to do that work.

Reviewed-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

1 files changed, 13 insertions, 38 deletions

diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
index 99213d744e4f..4f2dce686600 100644
--- a/virt/kvm/arm/vgic/vgic-v3.c
+++ b/virt/kvm/arm/vgic/vgic-v3.c
@@ -21,50 +21,17 @@
 
 #include "vgic.h"
 
-void vgic_v3_process_maintenance(struct kvm_vcpu *vcpu)
+void vgic_v3_set_underflow(struct kvm_vcpu *vcpu)
 {
 	struct vgic_v3_cpu_if *cpuif = &vcpu->arch.vgic_cpu.vgic_v3;
-	u32 model = vcpu->kvm->arch.vgic.vgic_model;
-
-	if (cpuif->vgic_misr & ICH_MISR_EOI) {
-		unsigned long eisr_bmap = cpuif->vgic_eisr;
-		int lr;
-
-		for_each_set_bit(lr, &eisr_bmap, kvm_vgic_global_state.nr_lr) {
-			u32 intid;
-			u64 val = cpuif->vgic_lr[lr];
-
-			if (model == KVM_DEV_TYPE_ARM_VGIC_V3)
-				intid = val & ICH_LR_VIRTUAL_ID_MASK;
-			else
-				intid = val & GICH_LR_VIRTUALID;
-
-			WARN_ON(cpuif->vgic_lr[lr] & ICH_LR_STATE);
-
-			/* Only SPIs require notification */
-			if (vgic_valid_spi(vcpu->kvm, intid))
-				kvm_notify_acked_irq(vcpu->kvm, 0,
-						     intid - VGIC_NR_PRIVATE_IRQS);
-		}
-
-		/*
-		 * In the next iterations of the vcpu loop, if we sync
-		 * the vgic state after flushing it, but before
-		 * entering the guest (this happens for pending
-		 * signals and vmid rollovers), then make sure we
-		 * don't pick up any old maintenance interrupts here.
-		 */
-		cpuif->vgic_eisr = 0;
-	}
 
-	cpuif->vgic_hcr &= ~ICH_HCR_UIE;
+	cpuif->vgic_hcr |= ICH_HCR_UIE;
 }
 
-void vgic_v3_set_underflow(struct kvm_vcpu *vcpu)
+static bool lr_signals_eoi_mi(u64 lr_val)
 {
-	struct vgic_v3_cpu_if *cpuif = &vcpu->arch.vgic_cpu.vgic_v3;
-
-	cpuif->vgic_hcr |= ICH_HCR_UIE;
+	return !(lr_val & ICH_LR_STATE) && (lr_val & ICH_LR_EOI) &&
+	       !(lr_val & ICH_LR_HW);
 }
 
 void vgic_v3_fold_lr_state(struct kvm_vcpu *vcpu)
@@ -73,6 +40,8 @@ void vgic_v3_fold_lr_state(struct kvm_vcpu *vcpu)
 	u32 model = vcpu->kvm->arch.vgic.vgic_model;
 	int lr;
 
+	cpuif->vgic_hcr &= ~ICH_HCR_UIE;
+
 	for (lr = 0; lr < vcpu->arch.vgic_cpu.used_lrs; lr++) {
 		u64 val = cpuif->vgic_lr[lr];
 		u32 intid;
@@ -82,6 +51,12 @@ void vgic_v3_fold_lr_state(struct kvm_vcpu *vcpu)
 			intid = val & ICH_LR_VIRTUAL_ID_MASK;
 		else
 			intid = val & GICH_LR_VIRTUALID;
+
+		/* Notify fds when the guest EOI'ed a level-triggered IRQ */
+		if (lr_signals_eoi_mi(val) && vgic_valid_spi(vcpu->kvm, intid))
+			kvm_notify_acked_irq(vcpu->kvm, 0,
+					     intid - VGIC_NR_PRIVATE_IRQS);
+
 		irq = vgic_get_irq(vcpu->kvm, vcpu, intid);
 		if (!irq)	/* An LPI could have been unmapped. */
 			continue;