[PATCH 4/8] KVM: arm/arm64: Make vgic_v3_check_base more broadly usable

[Christoffer Dall]

As we are about to fiddle with the io device registration mechanism
let's be a little more careful in verifying the addresses we can ealier
on to provide error messages to the user at time related to him/her
setting overlapping addresses.  We still want to check a consistent
system before actually running the VM for the first time, so we make
vgic_v3_check_base available in the core vgic-v3 code as well as in the
other parts of the GICv3 code, namely the MMIO config code.

We also return true for undefined base addresses so that the function
can be used before all base addresses are set; all callers already check
for uninitialized addresses before calling this function.

Signed-off-by: Christoffer Dall <cdall at linaro.org>
---
 virt/kvm/arm/vgic/vgic-v3.c | 18 ++++++++++++++----
 virt/kvm/arm/vgic/vgic.h    |  1 +
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
index 12e52a0..b934e78 100644
--- a/virt/kvm/arm/vgic/vgic-v3.c
+++ b/virt/kvm/arm/vgic/vgic-v3.c
@@ -329,19 +329,29 @@ int vgic_v3_save_pending_tables(struct kvm *kvm)
 	return 0;
 }
 
-/* check for overlapping regions and for regions crossing the end of memory */
-static bool vgic_v3_check_base(struct kvm *kvm)
+/*
+ * Check for overlapping regions and for regions crossing the end of memory
+ * for base addresses which have already been set.
+ */
+bool vgic_v3_check_base(struct kvm *kvm)
 {
 	struct vgic_dist *d = &kvm->arch.vgic;
 	gpa_t redist_size = KVM_VGIC_V3_REDIST_SIZE;
 
 	redist_size *= atomic_read(&kvm->online_vcpus);
 
-	if (d->vgic_dist_base + KVM_VGIC_V3_DIST_SIZE < d->vgic_dist_base)
+	if (!IS_VGIC_ADDR_UNDEF(d->vgic_dist_base) &&
+	    d->vgic_dist_base + KVM_VGIC_V3_DIST_SIZE < d->vgic_dist_base)
 		return false;
-	if (d->vgic_redist_base + redist_size < d->vgic_redist_base)
+
+	if (!IS_VGIC_ADDR_UNDEF(d->vgic_redist_base) &&
+	    d->vgic_redist_base + redist_size < d->vgic_redist_base)
 		return false;
 
+	if (IS_VGIC_ADDR_UNDEF(d->vgic_dist_base) &&
+	    IS_VGIC_ADDR_UNDEF(d->vgic_redist_base))
+		return true;
+
 	if (d->vgic_dist_base + KVM_VGIC_V3_DIST_SIZE <= d->vgic_redist_base)
 		return true;
 	if (d->vgic_redist_base + redist_size <= d->vgic_dist_base)
diff --git a/virt/kvm/arm/vgic/vgic.h b/virt/kvm/arm/vgic/vgic.h
index a2aeaa8..89eb935 100644
--- a/virt/kvm/arm/vgic/vgic.h
+++ b/virt/kvm/arm/vgic/vgic.h
@@ -175,6 +175,7 @@ int vgic_v3_map_resources(struct kvm *kvm);
 int vgic_v3_lpi_sync_pending_status(struct kvm *kvm, struct vgic_irq *irq);
 int vgic_v3_save_pending_tables(struct kvm *kvm);
 int vgic_register_redist_iodevs(struct kvm *kvm);
+bool vgic_v3_check_base(struct kvm *kvm);
 
 void vgic_v3_load(struct kvm_vcpu *vcpu);
 void vgic_v3_put(struct kvm_vcpu *vcpu);
-- 
2.9.0