tap: add Linux multiqueue support

This patch add basic multiqueue support for Linux. When multiqueue is needed, we
will first check whether kernel support multiqueue tap before creating more
queues. Two new functions tap_fd_enable() and tap_fd_disable() were introduced
to enable and disable a specific queue. Since the multiqueue is only supported
in Linux, return error on other platforms.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

diff --git a/net/tap-aix.c b/net/tap-aix.c
index aff6c527e9f4e8f8b13d7df040c071dc72808c62..66e0574fd7c5658dd0d7bbd56a132d146361bbdc 100644 (file)
--- a/net/tap-aix.c
+++ b/net/tap-aix.c
@@ -59,3 +59,13 @@ void tap_fd_set_offload(int fd, int csum, int tso4,
                         int tso6, int ecn, int ufo)
 {
 }
+
+int tap_fd_enable(int fd)
+{
+    return -1;
+}
+
+int tap_fd_disable(int fd)
+{
+    return -1;
+}

diff --git a/net/tap-bsd.c b/net/tap-bsd.c
index 01c705b4c03c891b2882de809ece9049a7a1ef48..cfc7a289f884069cb9a94cfe0c85af5b82a20b10 100644 (file)
--- a/net/tap-bsd.c
+++ b/net/tap-bsd.c
@@ -145,3 +145,14 @@ void tap_fd_set_offload(int fd, int csum, int tso4,
                         int tso6, int ecn, int ufo)
 {
 }
+
+int tap_fd_enable(int fd)
+{
+    return -1;
+}
+
+int tap_fd_disable(int fd)
+{
+    return -1;
+}
+

diff --git a/net/tap-haiku.c b/net/tap-haiku.c
index 08cc034cee3d86566dbd50de06e5f07e1a5a6ab2..664d40fb4dc87c2a1b2d1bbe700be8a98cdd52bc 100644 (file)
--- a/net/tap-haiku.c
+++ b/net/tap-haiku.c
@@ -59,3 +59,14 @@ void tap_fd_set_offload(int fd, int csum, int tso4,
                         int tso6, int ecn, int ufo)
 {
 }
+
+int tap_fd_enable(int fd)
+{
+    return -1;
+}
+
+int tap_fd_disable(int fd)
+{
+    return -1;
+}
+

diff --git a/net/tap-linux.c b/net/tap-linux.c
index 0a6acc7d5af0cc7b17e391016fa6b80297a76b38..bdb0a790c8ead8180ec2a93cfde83762dca43d94 100644 (file)
--- a/net/tap-linux.c
+++ b/net/tap-linux.c
@@ -41,6 +41,7 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr, int vnet_hdr_required
     struct ifreq ifr;
     int fd, ret;
     int len = sizeof(struct virtio_net_hdr);
+    int mq_required = 0;
 
     TFR(fd = open(PATH_NET_TUN, O_RDWR));
     if (fd < 0) {
@@ -76,6 +77,20 @@ int tap_open(char *ifname, int ifname_size, int *vnet_hdr, int vnet_hdr_required
         ioctl(fd, TUNSETVNETHDRSZ, &len);
     }
 
+    if (mq_required) {
+        unsigned int features;
+
+        if ((ioctl(fd, TUNGETFEATURES, &features) != 0) ||
+            !(features & IFF_MULTI_QUEUE)) {
+            error_report("multiqueue required, but no kernel "
+                         "support for IFF_MULTI_QUEUE available");
+            close(fd);
+            return -1;
+        } else {
+            ifr.ifr_flags |= IFF_MULTI_QUEUE;
+        }
+    }
+
     if (ifname[0] != '\0')
         pstrcpy(ifr.ifr_name, IFNAMSIZ, ifname);
     else
@@ -209,3 +224,40 @@ void tap_fd_set_offload(int fd, int csum, int tso4,
         }
     }
 }
+
+/* Enable a specific queue of tap. */
+int tap_fd_enable(int fd)
+{
+    struct ifreq ifr;
+    int ret;
+
+    memset(&ifr, 0, sizeof(ifr));
+
+    ifr.ifr_flags = IFF_ATTACH_QUEUE;
+    ret = ioctl(fd, TUNSETQUEUE, (void *) &ifr);
+
+    if (ret != 0) {
+        error_report("could not enable queue");
+    }
+
+    return ret;
+}
+
+/* Disable a specific queue of tap/ */
+int tap_fd_disable(int fd)
+{
+    struct ifreq ifr;
+    int ret;
+
+    memset(&ifr, 0, sizeof(ifr));
+
+    ifr.ifr_flags = IFF_DETACH_QUEUE;
+    ret = ioctl(fd, TUNSETQUEUE, (void *) &ifr);
+
+    if (ret != 0) {
+        error_report("could not disable queue");
+    }
+
+    return ret;
+}
+

diff --git a/net/tap-solaris.c b/net/tap-solaris.c
index 486a7ea838c97d7beb2843ed4cd02add1393c895..12cc392c94ff2f66233c9fec25b74f173322d7c6 100644 (file)
--- a/net/tap-solaris.c
+++ b/net/tap-solaris.c
@@ -225,3 +225,14 @@ void tap_fd_set_offload(int fd, int csum, int tso4,
                         int tso6, int ecn, int ufo)
 {
 }
+
+int tap_fd_enable(int fd)
+{
+    return -1;
+}
+
+int tap_fd_disable(int fd)
+{
+    return -1;
+}
+

diff --git a/net/tap_int.h b/net/tap_int.h
index 1dffe12a452c5178b6ca8cbebf4cc199789844e8..ca1c21b451a5c034906f03ba8f58ffca2d208706 100644 (file)
--- a/net/tap_int.h
+++ b/net/tap_int.h
@@ -42,5 +42,7 @@ int tap_probe_vnet_hdr_len(int fd, int len);
 int tap_probe_has_ufo(int fd);
 void tap_fd_set_offload(int fd, int csum, int tso4, int tso6, int ecn, int ufo);
 void tap_fd_set_vnet_hdr_len(int fd, int len);
+int tap_fd_enable(int fd);
+int tap_fd_disable(int fd);
 
 #endif /* QEMU_TAP_H */