From d73066c047a0cf2e4286023320512d059ac2b405 Mon Sep 17 00:00:00 2001
From: Eric Auger <eric.auger@redhat.com>
Date: Fri, 13 Dec 2019 10:42:37 +0100
Subject: [PATCH] KVM: arm/arm64: vgic-its: Fix restoration of unmapped
 collections

commit 8c58be34494b7f1b2adb446e2d8beeb90e5de65b upstream.

Saving/restoring an unmapped collection is a valid scenario. For
example this happens if a MAPTI command was sent, featuring an
unmapped collection. At the moment the CTE fails to be restored.
Only compare against the number of online vcpus if the rdist
base is set.

Fixes: ea1ad53e1e31a ("KVM: arm64: vgic-its: Collection table save/restore")
Signed-off-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Zenghui Yu <yuzenghui@huawei.com>
Link: https://lore.kernel.org/r/20191213094237.19627-1-eric.auger@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 virt/kvm/arm/vgic/vgic-its.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
index 526d808ecbbd9..8354ec4ef912e 100644
--- a/virt/kvm/arm/vgic/vgic-its.c
+++ b/virt/kvm/arm/vgic/vgic-its.c
@@ -2210,7 +2210,8 @@ static int vgic_its_restore_cte(struct vgic_its *its, gpa_t gpa, int esz)
 	target_addr = (u32)(val >> KVM_ITS_CTE_RDBASE_SHIFT);
 	coll_id = val & KVM_ITS_CTE_ICID_MASK;
 
-	if (target_addr >= atomic_read(&kvm->online_vcpus))
+	if (target_addr != COLLECTION_NOT_MAPPED &&
+	    target_addr >= atomic_read(&kvm->online_vcpus))
 		return -EINVAL;
 
 	collection = find_collection(its, coll_id);
-- 
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