KVM: arm64: Replace vgic_v3_uaccess_read_pending with vgic_uaccess_read_pending

Now that GICv2 has a proper userspace accessor for the pending state,
switch GICv3 over to it, dropping the local version, moving over the
specific behaviours that CGIv3 requires (such as the distinction
between pending latch and line level which were never enforced
with GICv2).

We also gain extra locking that isn't really necessary for userspace,
but that's a small price to pay for getting rid of superfluous code.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Link: https://lore.kernel.org/r/20220607131427.1164881-3-maz@kernel.org

arch/arm64/kvm/vgic/vgic-mmio-v3.c

@@ -353,42 +353,6 @@ static unsigned long vgic_mmio_read_v3_idregs(struct kvm_vcpu *vcpu,
 	return 0;
 }
 
-static unsigned long vgic_v3_uaccess_read_pending(struct kvm_vcpu *vcpu,
-						  gpa_t addr, unsigned int len)
-{
-	u32 intid = VGIC_ADDR_TO_INTID(addr, 1);
-	u32 value = 0;
-	int i;
-
-	/*
-	 * pending state of interrupt is latched in pending_latch variable.
-	 * Userspace will save and restore pending state and line_level
-	 * separately.
-	 * Refer to Documentation/virt/kvm/devices/arm-vgic-v3.rst
-	 * for handling of ISPENDR and ICPENDR.
-	 */
-	for (i = 0; i < len * 8; i++) {
-		struct vgic_irq *irq = vgic_get_irq(vcpu->kvm, vcpu, intid + i);
-		bool state = irq->pending_latch;
-
-		if (irq->hw && vgic_irq_is_sgi(irq->intid)) {
-			int err;
-
-			err = irq_get_irqchip_state(irq->host_irq,
-						    IRQCHIP_STATE_PENDING,
-						    &state);
-			WARN_ON(err);
-		}
-
-		if (state)
-			value |= (1U << i);
-
-		vgic_put_irq(vcpu->kvm, irq);
-	}
-
-	return value;
-}
-
 static int vgic_v3_uaccess_write_pending(struct kvm_vcpu *vcpu,
 					 gpa_t addr, unsigned int len,
 					 unsigned long val)
@@ -666,7 +630,7 @@ static const struct vgic_register_region vgic_v3_dist_registers[] = {
 		VGIC_ACCESS_32bit),
 	REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(GICD_ISPENDR,
 		vgic_mmio_read_pending, vgic_mmio_write_spending,
-		vgic_v3_uaccess_read_pending, vgic_v3_uaccess_write_pending, 1,
+		vgic_uaccess_read_pending, vgic_v3_uaccess_write_pending, 1,
 		VGIC_ACCESS_32bit),
 	REGISTER_DESC_WITH_BITS_PER_IRQ_SHARED(GICD_ICPENDR,
 		vgic_mmio_read_pending, vgic_mmio_write_cpending,
@@ -750,7 +714,7 @@ static const struct vgic_register_region vgic_v3_rd_registers[] = {
 		VGIC_ACCESS_32bit),
 	REGISTER_DESC_WITH_LENGTH_UACCESS(SZ_64K + GICR_ISPENDR0,
 		vgic_mmio_read_pending, vgic_mmio_write_spending,
-		vgic_v3_uaccess_read_pending, vgic_v3_uaccess_write_pending, 4,
+		vgic_uaccess_read_pending, vgic_v3_uaccess_write_pending, 4,
 		VGIC_ACCESS_32bit),
 	REGISTER_DESC_WITH_LENGTH_UACCESS(SZ_64K + GICR_ICPENDR0,
 		vgic_mmio_read_pending, vgic_mmio_write_cpending,

arch/arm64/kvm/vgic/vgic-mmio.c

@@ -240,6 +240,15 @@ static unsigned long __read_pending(struct kvm_vcpu *vcpu,
 		unsigned long flags;
 		bool val;
 
+		/*
+		 * When used from userspace with a GICv3 model:
+		 *
+		 * Pending state of interrupt is latched in pending_latch
+		 * variable.  Userspace will save and restore pending state
+		 * and line_level separately.
+		 * Refer to Documentation/virt/kvm/devices/arm-vgic-v3.rst
+		 * for handling of ISPENDR and ICPENDR.
+		 */
 		raw_spin_lock_irqsave(&irq->irq_lock, flags);
 		if (irq->hw && vgic_irq_is_sgi(irq->intid)) {
 			int err;
@@ -252,7 +261,17 @@ static unsigned long __read_pending(struct kvm_vcpu *vcpu,
 		} else if (!is_user && vgic_irq_is_mapped_level(irq)) {
 			val = vgic_get_phys_line_level(irq);
 		} else {
-			val = irq_is_pending(irq);
+			switch (vcpu->kvm->arch.vgic.vgic_model) {
+			case KVM_DEV_TYPE_ARM_VGIC_V3:
+				if (is_user) {
+					val = irq->pending_latch;
+					break;
+				}
+				fallthrough;
+			default:
+				val = irq_is_pending(irq);
+				break;
+			}
 		}
 
 		value |= ((u32)val << i);