[PATCH 1/4] KVM: arm64: vgic: Check that new ITEs could be saved in guest memory

[Ricardo Koller <ricarkol@google.com>]

A command that adds an entry into an ITS table that is not in guest
memory should fail, as any command should be treated as if it was
actually saving entries in guest memory (KVM doesn't until saving).
Add the corresponding check for the ITT when adding ITEs.

Signed-off-by: Ricardo Koller <ricarkol@google.com>
---
 arch/arm64/kvm/vgic/vgic-its.c | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/arch/arm64/kvm/vgic/vgic-its.c b/arch/arm64/kvm/vgic/vgic-its.c
index 2e13402be3bd..d7c1a3a01af4 100644
--- a/arch/arm64/kvm/vgic/vgic-its.c
+++ b/arch/arm64/kvm/vgic/vgic-its.c
@@ -976,6 +976,37 @@ static bool vgic_its_check_id(struct vgic_its *its, u64 baser, u32 id,
 	return ret;
 }
 
+/*
+ * Check whether an event ID can be stored in the corresponding Interrupt
+ * Translation Table, which starts at device->itt_addr.
+ */
+static bool vgic_its_check_ite(struct vgic_its *its, struct its_device *device,
+		u32 event_id)
+{
+	const struct vgic_its_abi *abi = vgic_its_get_abi(its);
+	int ite_esz = abi->ite_esz;
+	gpa_t gpa;
+	gfn_t gfn;
+	int idx;
+	bool ret;
+
+	/* max table size is: BIT_ULL(device->num_eventid_bits) * ite_esz */
+	if (event_id >= BIT_ULL(device->num_eventid_bits))
+		return false;
+
+	gpa = device->itt_addr + event_id * ite_esz;
+	gfn = gpa >> PAGE_SHIFT;
+
+	idx = srcu_read_lock(&its->dev->kvm->srcu);
+	ret = kvm_is_visible_gfn(its->dev->kvm, gfn);
+	srcu_read_unlock(&its->dev->kvm->srcu, idx);
+	return ret;
+}
+
+/*
+ * Adds a new collection into the ITS collection table.
+ * Returns 0 on success, and a negative error value for generic errors.
+ */
 static int vgic_its_alloc_collection(struct vgic_its *its,
 				     struct its_collection **colp,
 				     u32 coll_id)
@@ -1076,6 +1107,9 @@ static int vgic_its_cmd_handle_mapi(struct kvm *kvm, struct vgic_its *its,
 	if (find_ite(its, device_id, event_id))
 		return 0;
 
+	if (!vgic_its_check_ite(its, device, event_id))
+		return E_ITS_MAPTI_ID_OOR;
+
 	collection = find_collection(its, coll_id);
 	if (!collection) {
 		int ret = vgic_its_alloc_collection(its, &collection, coll_id);
-- 
2.36.0.rc2.479.g8af0fa9b8e-goog