[Qemu-devel] [PATCH v2] tests/vhost-user-bridge: add scattering of incoming packets

[Victor Kaplansky]

This patch adds to the vubr test the scattering of incoming
packets to the chain of RX buffer.  Also, this patch corrects the
size of the header preceding the packet in RX buffers.

Note that this patch doesn't add the support for mergeable
buffers.

Signed-off-by: Victor Kaplansky <address@hidden>
---
v2 changes:
    - don't propose VIRTIO_F_VERSION_1 during negotiation.
    - renamed variable: remained_len -> remaining_len?

 tests/vhost-user-bridge.c | 92 +++++++++++++++++++++++++++++++----------------
 1 file changed, 61 insertions(+), 31 deletions(-)

diff --git a/tests/vhost-user-bridge.c b/tests/vhost-user-bridge.c
index 9a1ad5a1..f2b6c67e 100644
--- a/tests/vhost-user-bridge.c
+++ b/tests/vhost-user-bridge.c
@@ -37,6 +37,7 @@
 #include <sys/eventfd.h>
 #include <arpa/inet.h>
 #include <netdb.h>
+#include <qemu/osdep.h>
 
 #include <linux/vhost.h>
 
@@ -176,6 +177,8 @@ typedef struct VubrVirtq {
 
 #define VHOST_MEMORY_MAX_NREGIONS    8
 #define VHOST_USER_F_PROTOCOL_FEATURES 30
+/* v1.0 compliant. */
+#define VIRTIO_F_VERSION_1             32
 
 #define VHOST_LOG_PAGE 4096
 
@@ -284,6 +287,7 @@ typedef struct VubrDev {
     struct sockaddr_in backend_udp_dest;
     int ready;
     uint64_t features;
+    int hdrlen;
 } VubrDev;
 
 static const char *vubr_request_str[] = {
@@ -474,7 +478,8 @@ vubr_backend_udp_recvbuf(VubrDev *dev, uint8_t *buf, size_t 
buflen)
 static void
 vubr_consume_raw_packet(VubrDev *dev, uint8_t *buf, uint32_t len)
 {
-    int hdrlen = sizeof(struct virtio_net_hdr_v1);
+    int hdrlen = dev->hdrlen;
+    DPRINT("    hdrlen = %d\n", dev->hdrlen);
 
     if (VHOST_USER_BRIDGE_DEBUG) {
         print_buffer(buf, len);
@@ -536,6 +541,7 @@ vubr_post_buffer(VubrDev *dev, VubrVirtq *vq, uint8_t *buf, 
int32_t len)
     struct vring_avail *avail = vq->avail;
     struct vring_used *used = vq->used;
     uint64_t log_guest_addr = vq->log_guest_addr;
+    int32_t remaining_len = len;
 
     unsigned int size = vq->size;
 
@@ -550,36 +556,49 @@ vubr_post_buffer(VubrDev *dev, VubrVirtq *vq, uint8_t 
*buf, int32_t len)
     uint16_t d_index = avail->ring[a_index];
 
     int i = d_index;
+    uint32_t written_len = 0;
 
-    DPRINT("Post packet to guest on vq:\n");
-    DPRINT("    size             = %d\n", vq->size);
-    DPRINT("    last_avail_index = %d\n", vq->last_avail_index);
-    DPRINT("    last_used_index  = %d\n", vq->last_used_index);
-    DPRINT("    a_index = %d\n", a_index);
-    DPRINT("    u_index = %d\n", u_index);
-    DPRINT("    d_index = %d\n", d_index);
-    DPRINT("    desc[%d].addr    = 0x%016"PRIx64"\n", i, desc[i].addr);
-    DPRINT("    desc[%d].len     = %d\n", i, desc[i].len);
-    DPRINT("    desc[%d].flags   = %d\n", i, desc[i].flags);
-    DPRINT("    avail->idx = %d\n", avail_index);
-    DPRINT("    used->idx  = %d\n", used->idx);
-
-    if (!(desc[i].flags & VRING_DESC_F_WRITE)) {
-        /* FIXME: we should find writable descriptor. */
-        fprintf(stderr, "Error: descriptor is not writable. Exiting.\n");
-        exit(1);
-    }
+    do {
+        DPRINT("Post packet to guest on vq:\n");
+        DPRINT("    size             = %d\n", vq->size);
+        DPRINT("    last_avail_index = %d\n", vq->last_avail_index);
+        DPRINT("    last_used_index  = %d\n", vq->last_used_index);
+        DPRINT("    a_index = %d\n", a_index);
+        DPRINT("    u_index = %d\n", u_index);
+        DPRINT("    d_index = %d\n", d_index);
+        DPRINT("    desc[%d].addr    = 0x%016"PRIx64"\n", i, desc[i].addr);
+        DPRINT("    desc[%d].len     = %d\n", i, desc[i].len);
+        DPRINT("    desc[%d].flags   = %d\n", i, desc[i].flags);
+        DPRINT("    avail->idx = %d\n", avail_index);
+        DPRINT("    used->idx  = %d\n", used->idx);
+
+        if (!(desc[i].flags & VRING_DESC_F_WRITE)) {
+            /* FIXME: we should find writable descriptor. */
+            fprintf(stderr, "Error: descriptor is not writable. Exiting.\n");
+            exit(1);
+        }
 
-    void *chunk_start = (void *)gpa_to_va(dev, desc[i].addr);
-    uint32_t chunk_len = desc[i].len;
+        void *chunk_start = (void *)gpa_to_va(dev, desc[i].addr);
+        uint32_t chunk_len = desc[i].len;
+        uint32_t chunk_write_len = MIN(remaining_len, chunk_len);
 
-    if (len <= chunk_len) {
-        memcpy(chunk_start, buf, len);
-        vubr_log_write(dev, desc[i].addr, len);
-    } else {
-        fprintf(stderr,
-                "Received too long packet from the backend. Dropping...\n");
-        return;
+        memcpy(chunk_start, buf + written_len, chunk_write_len);
+        vubr_log_write(dev, desc[i].addr, chunk_write_len);
+        remaining_len -= chunk_write_len;
+        written_len += chunk_write_len;
+
+        if ((remaining_len == 0) || !(desc[i].flags & VRING_DESC_F_NEXT)) {
+            break;
+        }
+
+        i = desc[i].next;
+    } while (1);
+
+    if (remaining_len > 0) {
+            fprintf(stderr,
+                    "Too long packet for RX, remaining_len = %d, 
Dropping...\n",
+                    remaining_len);
+            return;
     }
 
     /* Add descriptor to the used ring. */
@@ -687,7 +706,7 @@ vubr_backend_recv_cb(int sock, void *ctx)
     VubrVirtq *rx_vq = &dev->vq[0];
     uint8_t buf[4096];
     struct virtio_net_hdr_v1 *hdr = (struct virtio_net_hdr_v1 *)buf;
-    int hdrlen = sizeof(struct virtio_net_hdr_v1);
+    int hdrlen = dev->hdrlen;
     int buflen = sizeof(buf);
     int len;
 
@@ -696,6 +715,7 @@ vubr_backend_recv_cb(int sock, void *ctx)
     }
 
     DPRINT("\n\n   ***   IN UDP RECEIVE CALLBACK    ***\n\n");
+    DPRINT("    hdrlen = %d\n", hdrlen);
 
     uint16_t avail_index = atomic_mb_read(&rx_vq->avail->idx);
 
@@ -707,10 +727,12 @@ vubr_backend_recv_cb(int sock, void *ctx)
         return;
     }
 
+    memset(buf, 0, hdrlen);
+    /* TODO: support mergeable buffers. */
+    if (hdrlen == 12)
+        hdr->num_buffers = 1;
     len = vubr_backend_udp_recvbuf(dev, buf + hdrlen, buflen - hdrlen);
 
-    *hdr = (struct virtio_net_hdr_v1) { };
-    hdr->num_buffers = 1;
     vubr_post_buffer(dev, rx_vq, buf, len + hdrlen);
 }
 
@@ -758,7 +780,15 @@ static int
 vubr_set_features_exec(VubrDev *dev, VhostUserMsg *vmsg)
 {
     DPRINT("u64: 0x%016"PRIx64"\n", vmsg->payload.u64);
+
     dev->features = vmsg->payload.u64;
+    if ((dev->features & (1ULL << VIRTIO_F_VERSION_1)) ||
+        (dev->features & (1ULL << VIRTIO_NET_F_MRG_RXBUF))) {
+        dev->hdrlen = 12;
+    } else {
+        dev->hdrlen = 10;
+    }
+
     return 0;
 }
 
-- 
Victor