FAILED: patch "[PATCH] KVM: arm/arm64: Fix KVM_VGIC_V3_ADDR_TYPE_REDIST read" failed to apply to 5.4-stable tree

The patch below does not apply to the 5.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 94ac0835391efc1a30feda6fc908913ec012951e Mon Sep 17 00:00:00 2001
From: Eric Auger <[email protected]>
Date: Mon, 12 Apr 2021 17:00:34 +0200
Subject: [PATCH] KVM: arm/arm64: Fix KVM_VGIC_V3_ADDR_TYPE_REDIST read

When reading the base address of the a REDIST region through KVM_VGIC_V3_ADDR_TYPE_REDIST we expect the redistributor region list to be populated with a single element.

However list_first_entry() expects the list to be non empty. Instead we should use list_first_entry_or_null which effectively returns NULL if the list is empty.

index 2f66cf247282..7740995de982 100644
@@ -87,8 +87,8 @@ int kvm_vgic_addr(struct kvm *kvm, unsigned long type, u64 *addr, bool write)
 			r = vgic_v3_set_redist_base(kvm, 0, *addr, 0);
 			goto out;
 		}
-		rdreg = list_first_entry(&vgic->rd_regions,
-					 struct vgic_redist_region, list);
+		rdreg = list_first_entry_or_null(&vgic->rd_regions,
+						 struct vgic_redist_region, list);
 		if (!rdreg)
 			addr_ptr = &undef_value;
 		else