vhost: fix guest to host physical address mapping

Async copy fails when looking up hpa in the gpa to hpa mapping table.
This happens because the gpa is matched exactly in the merged
mapping table, and the merge loses the mapping entries.
A new range comparison method is introduced to solve this issue.

Fixes: 6563cf9 ("vhost: fix async copy on multi-page buffers")
Cc: stable@dpdk.org

Signed-off-by: Yuan Wang <yuanx.wang@intel.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

lib/vhost/vhost.h

@@ -587,6 +587,20 @@ static __rte_always_inline int guest_page_addrcmp(const void *p1,
 	return 0;
 }
 
+static __rte_always_inline int guest_page_rangecmp(const void *p1, const void *p2)
+{
+	const struct guest_page *page1 = (const struct guest_page *)p1;
+	const struct guest_page *page2 = (const struct guest_page *)p2;
+
+	if (page1->guest_phys_addr >= page2->guest_phys_addr) {
+		if (page1->guest_phys_addr < page2->guest_phys_addr + page2->size)
+			return 0;
+		else
+			return 1;
+	} else
+		return -1;
+}
+
 static __rte_always_inline rte_iova_t
 gpa_to_first_hpa(struct virtio_net *dev, uint64_t gpa,
 	uint64_t gpa_size, uint64_t *hpa_size)
@@ -597,9 +611,9 @@ gpa_to_first_hpa(struct virtio_net *dev, uint64_t gpa,
 
 	*hpa_size = gpa_size;
 	if (dev->nr_guest_pages >= VHOST_BINARY_SEARCH_THRESH) {
-		key.guest_phys_addr = gpa & ~(dev->guest_pages[0].size - 1);
+		key.guest_phys_addr = gpa;
 		page = bsearch(&key, dev->guest_pages, dev->nr_guest_pages,
-			       sizeof(struct guest_page), guest_page_addrcmp);
+			       sizeof(struct guest_page), guest_page_rangecmp);
 		if (page) {
 			if (gpa + gpa_size <=
 					page->guest_phys_addr + page->size) {