[PATCH v2 4/4] KVM: arm64: vgic-its: Point saved ITEs at the next valid entry

[Fuad Tabba <fuad.tabba@linux.dev>]

An ITE whose collection was dropped is saved as an invalid entry, and
vgic_its_restore_ite() has no offset to follow from one, so the scan
steps a single entry at a time until it reaches a valid entry or the
end of the ITT.

Compute the offset to the next ITE that is saved as valid instead.

Suggested-by: Oliver Upton <oupton@kernel.org>
Signed-off-by: Fuad Tabba <fuad.tabba@linux.dev>
---
 arch/arm64/kvm/vgic/vgic-its.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/arch/arm64/kvm/vgic/vgic-its.c b/arch/arm64/kvm/vgic/vgic-its.c
index 1589f06e66904..9e782a4fea7e5 100644
--- a/arch/arm64/kvm/vgic/vgic-its.c
+++ b/arch/arm64/kvm/vgic/vgic-its.c
@@ -2035,15 +2035,16 @@ static u32 compute_next_devid_offset(struct list_head *h,
 
 static u32 compute_next_eventid_offset(struct list_head *h, struct its_ite *ite)
 {
-	struct its_ite *next;
-	u32 next_offset;
+	struct its_ite *next = ite;
 
-	if (list_is_last(&ite->ite_list, h))
-		return 0;
-	next = list_next_entry(ite, ite_list);
-	next_offset = next->event_id - ite->event_id;
+	/* Point at the next ITE that vgic_its_save_ite() stores as valid. */
+	list_for_each_entry_continue(next, h, ite_list) {
+		if (next->collection)
+			return min_t(u32, next->event_id - ite->event_id,
+				     VITS_ITE_MAX_EVENTID_OFFSET);
+	}
 
-	return min_t(u32, next_offset, VITS_ITE_MAX_EVENTID_OFFSET);
+	return 0;
 }
 
 /**
-- 
2.39.5