[PATCH] vhost: fix get hpa fail from guest pages

[Yuan Wang]

When processing front-end memory regions messages,
vhost saves the guest/host physical address mappings to guest pages
and merges adjacent contiguous pages if hpa is contiguous,
however gpa is likely not contiguous in PA mode
and merging will cause the gpa range to change.
This patch distinguishes the case of discontinuous gpa
and does a range lookup on gpa when doing a binary search.

Fixes: e246896178e("vhost: get guest/host physical address mappings")
Fixes: 6563cf92380 ("vhost: fix async copy on multi-page buffers")

Signed-off-by: Yuan Wang <yuanx.wang at intel.com>
---
 lib/vhost/vhost.h      | 18 ++++++++++++++++--
 lib/vhost/vhost_user.c | 15 +++++++++++----
 2 files changed, 27 insertions(+), 6 deletions(-)

diff --git a/lib/vhost/vhost.h b/lib/vhost/vhost.h
index 7085e0885c..b3f0c1d07c 100644
--- a/lib/vhost/vhost.h
+++ b/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) {
diff --git a/lib/vhost/vhost_user.c b/lib/vhost/vhost_user.c
index a781346c4d..7d58fde458 100644
--- a/lib/vhost/vhost_user.c
+++ b/lib/vhost/vhost_user.c
@@ -999,10 +999,17 @@ add_one_guest_page(struct virtio_net *dev, uint64_t guest_phys_addr,
 	if (dev->nr_guest_pages > 0) {
 		last_page = &dev->guest_pages[dev->nr_guest_pages - 1];
 		/* merge if the two pages are continuous */
-		if (host_phys_addr == last_page->host_phys_addr +
-				      last_page->size) {
-			last_page->size += size;
-			return 0;
+		if (host_phys_addr == last_page->host_phys_addr + last_page->size) {
+			if (rte_eal_iova_mode() == RTE_IOVA_VA) {
+				last_page->size += size;
+				return 0;
+			}
+
+			if (rte_eal_iova_mode() == RTE_IOVA_PA &&
+				guest_phys_addr == last_page->guest_phys_addr + last_page->size) {
+				last_page->size += size;
+				return 0;
+			}
 		}
 	}
 
-- 
2.25.1