[PATCH v3 6/9] KVM: arm/arm64: Introduce an allocator for in-kernel irq lines

Christoffer Dall
2017-06-08T13:30:48Z

Having multiple devices being able to signal the same interrupt line is
very confusing and almost certainly guarantees a configuration error.

Therefore, introduce a very simple allocator which allows a device to
claim an interrupt line from the vgic for a given VM.

Signed-off-by: Christoffer Dall <cdall@linaro.org>
---
include/kvm/arm_vgic.h | 5 +++++
virt/kvm/arm/vgic/vgic.c | 33 +++++++++++++++++++++++++++++++++
2 files changed, 38 insertions(+)

diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index dde59fb..5d5b345 100644
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -121,6 +121,9 @@ struct vgic_irq {
u8 source; /* GICv2 SGIs only */
u8 priority;
enum vgic_irq_config config; /* Level or edge */
+
+ void *owner; /* Opaque pointer to reserve an interrupt
+ for in-kernel devices. */
};

struct vgic_register_region;
@@ -340,4 +343,6 @@ int kvm_send_userspace_msi(struct kvm *kvm, struct kvm_msi *msi);
*/
int kvm_vgic_setup_default_irq_routing(struct kvm *kvm);

+int kvm_vgic_set_owner(struct kvm_vcpu *vcpu, unsigned int intid, void *owner);
+
#endif /* __KVM_ARM_VGIC_H */
diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
index c66feac..9628945 100644
--- a/virt/kvm/arm/vgic/vgic.c
+++ b/virt/kvm/arm/vgic/vgic.c
@@ -435,6 +435,39 @@ int kvm_vgic_unmap_phys_irq(struct kvm_vcpu *vcpu, unsigned int virt_irq)
}

/**
+ * kvm_vgic_set_owner - Set the owner of an interrupt for a VM
+ *
+ * @vcpu: Pointer to the VCPU (used for PPIs)
+ * @intid: The virtual INTID identifying the interrupt (PPI or SPI)
+ * @owner: Opaque pointer to the owner
+ *
+ * Returns 0 if intid is not already used by another in-kernel device and the
+ * owner is set, otherwise returns an error code.
+ */
+int kvm_vgic_set_owner(struct kvm_vcpu *vcpu, unsigned int intid, void *owner)
+{
+ struct vgic_irq *irq;
+ int ret = 0;
+
+ if (!vgic_initialized(vcpu->kvm))
+ return -EAGAIN;
+
+ /* SGIs and LPIs cannot be wired up to any device */
+ if (!irq_is_ppi(intid) && !vgic_valid_spi(vcpu->kvm, intid))
+ return -EINVAL;
+
+ irq = vgic_get_irq(vcpu->kvm, vcpu, intid);
+ spin_lock(&irq->irq_lock);
+ if (irq->owner && irq->owner != owner)
+ ret = -EEXIST;
+ else
+ irq->owner = owner;
+ spin_unlock(&irq->irq_lock);
+
+ return ret;
+}
+
+/**
* vgic_prune_ap_list - Remove non-relevant interrupts from the list
*
* @vcpu: The VCPU pointer
--
2.9.0