[Qemu-devel] [PATCH 0/2] net: netmap: use nm_open() to open netmap port

[Qemu-devel] [PATCH 0/2] net: netmap: use nm_open() to open netmap port

[Vincenzo Maffione]

Current implementation of netmap backend still uses the low level netmap
API to open, register and close netmap ports. However, the netmap_user.h
header provides some helper functions that make these tasks easier, with
the additional advantage of extended interface name semantic.

As an example, the extended semantic allows to open a netmap pipe over
a VALE port by specifying an interface name in the form "valeXX:YY{ZZ".
Other suffixes are used for netmap monitors, exclusive access, and to
specify special binding mode (e.g. single queue, RX-only, TX-only, etc.).
Details can be found in the netmap man page and in the netmap API headers.

Vincenzo Maffione (2):
  net: netmap: use nm_open() to open netmap ports
  net: netmap: avoid mmap() when ports use the same shared memory area

 net/netmap.c | 129 ++++++++++++++++++++++++++++++-----------------------------
 1 file changed, 66 insertions(+), 63 deletions(-)

-- 
2.7.0

[Qemu-devel] [PATCH 1/2] net: netmap: use nm_open() to open netmap ports

[Vincenzo Maffione]

This patch simplifies the netmap backend code by means of the nm_open()
helper function provided by netmap_user.h, which hides the details of
open(), iotcl() and mmap() carried out on the netmap device.

Moreover, the semantic of nm_open() makes it possible to open special
netmap ports (e.g. pipes, monitors) and use special modes (e.g. host rings
only, single queue mode, exclusive access).

Signed-off-by: Vincenzo Maffione <v.maffione@gmail.com>
---
 net/netmap.c | 97 ++++++++++++++++++++----------------------------------------
 1 file changed, 32 insertions(+), 65 deletions(-)

diff --git a/net/netmap.c b/net/netmap.c
index 5558368..27295ab 100644
--- a/net/netmap.c
+++ b/net/netmap.c
@@ -39,21 +39,12 @@
 #include "qemu/error-report.h"
 #include "qemu/iov.h"
 
-/* Private netmap device info. */
-typedef struct NetmapPriv {
-    int                 fd;
-    size_t              memsize;
-    void                *mem;
-    struct netmap_if    *nifp;
-    struct netmap_ring  *rx;
-    struct netmap_ring  *tx;
-    char                fdname[PATH_MAX];        /* Normally "/dev/netmap". */
-    char                ifname[IFNAMSIZ];
-} NetmapPriv;
-
 typedef struct NetmapState {
     NetClientState      nc;
-    NetmapPriv          me;
+    struct nm_desc      *nmd;
+    char                ifname[IFNAMSIZ];
+    struct netmap_ring  *tx;
+    struct netmap_ring  *rx;
     bool                read_poll;
     bool                write_poll;
     struct iovec        iov[IOV_MAX];
@@ -90,44 +81,23 @@ pkt_copy(const void *_src, void *_dst, int l)
  * Open a netmap device. We assume there is only one queue
  * (which is the case for the VALE bridge).
  */
-static void netmap_open(NetmapPriv *me, Error **errp)
+static struct nm_desc *netmap_open(const NetdevNetmapOptions *nm_opts,
+                                   Error **errp)
 {
-    int fd;
-    int err;
-    size_t l;
+    struct nm_desc *nmd;
     struct nmreq req;
 
-    me->fd = fd = open(me->fdname, O_RDWR);
-    if (fd < 0) {
-        error_setg_file_open(errp, errno, me->fdname);
-        return;
-    }
     memset(&req, 0, sizeof(req));
-    pstrcpy(req.nr_name, sizeof(req.nr_name), me->ifname);
-    req.nr_ringid = NETMAP_NO_TX_POLL;
-    req.nr_version = NETMAP_API;
-    err = ioctl(fd, NIOCREGIF, &req);
-    if (err) {
-        error_setg_errno(errp, errno, "Unable to register %s", me->ifname);
-        goto error;
-    }
-    l = me->memsize = req.nr_memsize;
 
-    me->mem = mmap(0, l, PROT_WRITE | PROT_READ, MAP_SHARED, fd, 0);
-    if (me->mem == MAP_FAILED) {
-        error_setg_errno(errp, errno, "Unable to mmap netmap shared memory");
-        me->mem = NULL;
-        goto error;
+    nmd = nm_open(nm_opts->ifname, &req, NETMAP_NO_TX_POLL,
+                  NULL);
+    if (nmd == NULL) {
+        error_setg_errno(errp, errno, "Failed to nm_open() %s",
+                         nm_opts->ifname);
+        return NULL;
     }
 
-    me->nifp = NETMAP_IF(me->mem, req.nr_offset);
-    me->tx = NETMAP_TXRING(me->nifp, 0);
-    me->rx = NETMAP_RXRING(me->nifp, 0);
-
-    return;
-
-error:
-    close(me->fd);
+    return nmd;
 }
 
 static void netmap_send(void *opaque);
@@ -136,7 +106,7 @@ static void netmap_writable(void *opaque);
 /* Set the event-loop handlers for the netmap backend. */
 static void netmap_update_fd_handler(NetmapState *s)
 {
-    qemu_set_fd_handler(s->me.fd,
+    qemu_set_fd_handler(s->nmd->fd,
                         s->read_poll ? netmap_send : NULL,
                         s->write_poll ? netmap_writable : NULL,
                         s);
@@ -188,7 +158,7 @@ static ssize_t netmap_receive(NetClientState *nc,
       const uint8_t *buf, size_t size)
 {
     NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
-    struct netmap_ring *ring = s->me.tx;
+    struct netmap_ring *ring = s->tx;
     uint32_t i;
     uint32_t idx;
     uint8_t *dst;
@@ -218,7 +188,7 @@ static ssize_t netmap_receive(NetClientState *nc,
     ring->slot[i].flags = 0;
     pkt_copy(buf, dst, size);
     ring->cur = ring->head = nm_ring_next(ring, i);
-    ioctl(s->me.fd, NIOCTXSYNC, NULL);
+    ioctl(s->nmd->fd, NIOCTXSYNC, NULL);
 
     return size;
 }
@@ -227,7 +197,7 @@ static ssize_t netmap_receive_iov(NetClientState *nc,
                     const struct iovec *iov, int iovcnt)
 {
     NetmapState *s = DO_UPCAST(NetmapState, nc, nc);
-    struct netmap_ring *ring = s->me.tx;
+    struct netmap_ring *ring = s->tx;
     uint32_t last;
     uint32_t idx;
     uint8_t *dst;
@@ -284,7 +254,7 @@ static ssize_t netmap_receive_iov(NetClientState *nc,
     /* Now update ring->cur and ring->head. */
     ring->cur = ring->head = i;
 
-    ioctl(s->me.fd, NIOCTXSYNC, NULL);
+    ioctl(s->nmd->fd, NIOCTXSYNC, NULL);
 
     return iov_size(iov, iovcnt);
 }
@@ -301,7 +271,7 @@ static void netmap_send_completed(NetClientState *nc, ssize_t len)
 static void netmap_send(void *opaque)
 {
     NetmapState *s = opaque;
-    struct netmap_ring *ring = s->me.rx;
+    struct netmap_ring *ring = s->rx;
 
     /* Keep sending while there are available packets into the netmap
        RX ring and the forwarding path towards the peer is open. */
@@ -349,10 +319,8 @@ static void netmap_cleanup(NetClientState *nc)
     qemu_purge_queued_packets(nc);
 
     netmap_poll(nc, false);
-    munmap(s->me.mem, s->me.memsize);
-    close(s->me.fd);
-
-    s->me.fd = -1;
+    nm_close(s->nmd);
+    s->nmd = NULL;
 }
 
 /* Offloading manipulation support callbacks. */
@@ -383,17 +351,17 @@ static void netmap_set_vnet_hdr_len(NetClientState *nc, int len)
     struct nmreq req;
 
     /* Issue a NETMAP_BDG_VNET_HDR command to change the virtio-net header
-     * length for the netmap adapter associated to 'me->ifname'.
+     * length for the netmap adapter associated to 's->ifname'.
      */
     memset(&req, 0, sizeof(req));
-    pstrcpy(req.nr_name, sizeof(req.nr_name), s->me.ifname);
+    pstrcpy(req.nr_name, sizeof(req.nr_name), s->ifname);
     req.nr_version = NETMAP_API;
     req.nr_cmd = NETMAP_BDG_VNET_HDR;
     req.nr_arg1 = len;
-    err = ioctl(s->me.fd, NIOCREGIF, &req);
+    err = ioctl(s->nmd->fd, NIOCREGIF, &req);
     if (err) {
         error_report("Unable to execute NETMAP_BDG_VNET_HDR on %s: %s",
-                     s->me.ifname, strerror(errno));
+                     s->ifname, strerror(errno));
     } else {
         /* Keep track of the current length. */
         s->vnet_hdr_len = len;
@@ -437,16 +405,12 @@ int net_init_netmap(const NetClientOptions *opts,
                     const char *name, NetClientState *peer, Error **errp)
 {
     const NetdevNetmapOptions *netmap_opts = opts->u.netmap;
+    struct nm_desc *nmd;
     NetClientState *nc;
     Error *err = NULL;
-    NetmapPriv me;
     NetmapState *s;
 
-    pstrcpy(me.fdname, sizeof(me.fdname),
-        netmap_opts->has_devname ? netmap_opts->devname : "/dev/netmap");
-    /* Set default name for the port if not supplied. */
-    pstrcpy(me.ifname, sizeof(me.ifname), netmap_opts->ifname);
-    netmap_open(&me, &err);
+    nmd = netmap_open(netmap_opts, &err);
     if (err) {
         error_propagate(errp, err);
         return -1;
@@ -454,8 +418,11 @@ int net_init_netmap(const NetClientOptions *opts,
     /* Create the object. */
     nc = qemu_new_net_client(&net_netmap_info, peer, "netmap", name);
     s = DO_UPCAST(NetmapState, nc, nc);
-    s->me = me;
+    s->nmd = nmd;
+    s->tx = NETMAP_TXRING(nmd->nifp, 0);
+    s->rx = NETMAP_RXRING(nmd->nifp, 0);
     s->vnet_hdr_len = 0;
+    pstrcpy(s->ifname, sizeof(s->ifname), netmap_opts->ifname);
     netmap_read_poll(s, true); /* Initially only poll for reads. */
 
     return 0;
-- 
2.7.0

[Qemu-devel] [PATCH 2/2] net: netmap: avoid mmap() when ports use the same shared memory area

[Vincenzo Maffione]

With this patch, nm_open() does not mmap() the netmap device. This
operation is performed separately only if the memory area of the
port just opened was not known before.
A global list of netmap clients is kept to check when matches
occur.

Signed-off-by: Vincenzo Maffione <v.maffione@gmail.com>
---
 net/netmap.c | 38 +++++++++++++++++++++++++++++++++++++-
 1 file changed, 37 insertions(+), 1 deletion(-)

diff --git a/net/netmap.c b/net/netmap.c
index 27295ab..6a4c01c 100644
--- a/net/netmap.c
+++ b/net/netmap.c
@@ -49,8 +49,12 @@ typedef struct NetmapState {
     bool                write_poll;
     struct iovec        iov[IOV_MAX];
     int                 vnet_hdr_len;  /* Current virtio-net header length. */
+    QTAILQ_ENTRY(NetmapState) next;
 } NetmapState;
 
+static QTAILQ_HEAD(, NetmapState) netmap_clients =
+                   QTAILQ_HEAD_INITIALIZER(netmap_clients);
+
 #ifndef __FreeBSD__
 #define pkt_copy bcopy
 #else
@@ -78,6 +82,23 @@ pkt_copy(const void *_src, void *_dst, int l)
 #endif /* __FreeBSD__ */
 
 /*
+ * find nm_desc parent with same allocator
+ */
+static struct nm_desc *
+netmap_find_memory(struct nm_desc *nmd)
+{
+    NetmapState *s;
+
+    QTAILQ_FOREACH(s, &netmap_clients, next) {
+        if (nmd->req.nr_arg2 == s->nmd->req.nr_arg2) {
+            return s->nmd;
+        }
+    }
+
+    return NULL;
+}
+
+/*
  * Open a netmap device. We assume there is only one queue
  * (which is the case for the VALE bridge).
  */
@@ -86,10 +107,11 @@ static struct nm_desc *netmap_open(const NetdevNetmapOptions *nm_opts,
 {
     struct nm_desc *nmd;
     struct nmreq req;
+    int ret;
 
     memset(&req, 0, sizeof(req));
 
-    nmd = nm_open(nm_opts->ifname, &req, NETMAP_NO_TX_POLL,
+    nmd = nm_open(nm_opts->ifname, &req, NETMAP_NO_TX_POLL | NM_OPEN_NO_MMAP,
                   NULL);
     if (nmd == NULL) {
         error_setg_errno(errp, errno, "Failed to nm_open() %s",
@@ -97,6 +119,17 @@ static struct nm_desc *netmap_open(const NetdevNetmapOptions *nm_opts,
         return NULL;
     }
 
+    /* Check if we already have a nm_desc that uses the same memory as the one
+     * just opened, so that nm_mmap() can skip mmap() and inherit from parent.
+     */
+    ret = nm_mmap(nmd, netmap_find_memory(nmd));
+    if (ret) {
+        error_setg_errno(errp, errno, "Failed to nm_mmap() %s",
+                         nm_opts->ifname);
+        nm_close(nmd);
+        return NULL;
+    }
+
     return nmd;
 }
 
@@ -321,6 +354,8 @@ static void netmap_cleanup(NetClientState *nc)
     netmap_poll(nc, false);
     nm_close(s->nmd);
     s->nmd = NULL;
+
+    QTAILQ_REMOVE(&netmap_clients, s, next);
 }
 
 /* Offloading manipulation support callbacks. */
@@ -423,6 +458,7 @@ int net_init_netmap(const NetClientOptions *opts,
     s->rx = NETMAP_RXRING(nmd->nifp, 0);
     s->vnet_hdr_len = 0;
     pstrcpy(s->ifname, sizeof(s->ifname), netmap_opts->ifname);
+    QTAILQ_INSERT_TAIL(&netmap_clients, s, next);
     netmap_read_poll(s, true); /* Initially only poll for reads. */
 
     return 0;
-- 
2.7.0

Re: [Qemu-devel] [PATCH 2/2] net: netmap: avoid mmap() when ports use the same shared memory area

[Jason Wang]

On 01/08/2016 09:15 PM, Vincenzo Maffione wrote:
> With this patch, nm_open() does not mmap() the netmap device. This
> operation is performed separately only if the memory area of the
> port just opened was not known before.
> A global list of netmap clients is kept to check when matches
> occur.
>
> Signed-off-by: Vincenzo Maffione <v.maffione@gmail.com>
> ---
>  net/netmap.c | 38 +++++++++++++++++++++++++++++++++++++-
>  1 file changed, 37 insertions(+), 1 deletion(-)
>
> diff --git a/net/netmap.c b/net/netmap.c
> index 27295ab..6a4c01c 100644
> --- a/net/netmap.c
> +++ b/net/netmap.c
> @@ -49,8 +49,12 @@ typedef struct NetmapState {
>      bool                write_poll;
>      struct iovec        iov[IOV_MAX];
>      int                 vnet_hdr_len;  /* Current virtio-net header length. */
> +    QTAILQ_ENTRY(NetmapState) next;
>  } NetmapState;
>  
> +static QTAILQ_HEAD(, NetmapState) netmap_clients =
> +                   QTAILQ_HEAD_INITIALIZER(netmap_clients);
> +
>  #ifndef __FreeBSD__
>  #define pkt_copy bcopy
>  #else
> @@ -78,6 +82,23 @@ pkt_copy(const void *_src, void *_dst, int l)
>  #endif /* __FreeBSD__ */
>  
>  /*
> + * find nm_desc parent with same allocator
> + */
> +static struct nm_desc *
> +netmap_find_memory(struct nm_desc *nmd)
> +{
> +    NetmapState *s;
> +
> +    QTAILQ_FOREACH(s, &netmap_clients, next) {
> +        if (nmd->req.nr_arg2 == s->nmd->req.nr_arg2) {
> +            return s->nmd;
> +        }
> +    }
> +
> +    return NULL;
> +}
> +
> +/*
>   * Open a netmap device. We assume there is only one queue
>   * (which is the case for the VALE bridge).
>   */
> @@ -86,10 +107,11 @@ static struct nm_desc *netmap_open(const NetdevNetmapOptions *nm_opts,
>  {
>      struct nm_desc *nmd;
>      struct nmreq req;
> +    int ret;
>  
>      memset(&req, 0, sizeof(req));
>  
> -    nmd = nm_open(nm_opts->ifname, &req, NETMAP_NO_TX_POLL,
> +    nmd = nm_open(nm_opts->ifname, &req, NETMAP_NO_TX_POLL | NM_OPEN_NO_MMAP,
>                    NULL);
>      if (nmd == NULL) {
>          error_setg_errno(errp, errno, "Failed to nm_open() %s",
> @@ -97,6 +119,17 @@ static struct nm_desc *netmap_open(const NetdevNetmapOptions *nm_opts,
>          return NULL;
>      }
>  
> +    /* Check if we already have a nm_desc that uses the same memory as the one
> +     * just opened, so that nm_mmap() can skip mmap() and inherit from parent.
> +     */
> +    ret = nm_mmap(nmd, netmap_find_memory(nmd));

Looks like I could not find nm_mmap() definition in neither qemu or
freebsd source. Is there anything missed?

> +    if (ret) {
> +        error_setg_errno(errp, errno, "Failed to nm_mmap() %s",
> +                         nm_opts->ifname);
> +        nm_close(nmd);
> +        return NULL;
> +    }
> +
>      return nmd;
>  }
>  
> @@ -321,6 +354,8 @@ static void netmap_cleanup(NetClientState *nc)
>      netmap_poll(nc, false);
>      nm_close(s->nmd);
>      s->nmd = NULL;
> +
> +    QTAILQ_REMOVE(&netmap_clients, s, next);
>  }
>  
>  /* Offloading manipulation support callbacks. */
> @@ -423,6 +458,7 @@ int net_init_netmap(const NetClientOptions *opts,
>      s->rx = NETMAP_RXRING(nmd->nifp, 0);
>      s->vnet_hdr_len = 0;
>      pstrcpy(s->ifname, sizeof(s->ifname), netmap_opts->ifname);
> +    QTAILQ_INSERT_TAIL(&netmap_clients, s, next);
>      netmap_read_poll(s, true); /* Initially only poll for reads. */
>  
>      return 0;

Re: [Qemu-devel] [PATCH 2/2] net: netmap: avoid mmap() when ports use the same shared memory area

[Vincenzo Maffione]

No, you're right, nm_mmap() is not defined for all netmap versions.

It will take a while for us to decide how to manage this. Would it be
possible to go ahead with patch 1/2 only (I will reissue the patch
series)?

Cheers,
  Vincenzo

2016-01-14 4:25 GMT+01:00 Jason Wang <jasowang@redhat.com>:
>
>
> On 01/08/2016 09:15 PM, Vincenzo Maffione wrote:
>> With this patch, nm_open() does not mmap() the netmap device. This
>> operation is performed separately only if the memory area of the
>> port just opened was not known before.
>> A global list of netmap clients is kept to check when matches
>> occur.
>>
>> Signed-off-by: Vincenzo Maffione <v.maffione@gmail.com>
>> ---
>>  net/netmap.c | 38 +++++++++++++++++++++++++++++++++++++-
>>  1 file changed, 37 insertions(+), 1 deletion(-)
>>
>> diff --git a/net/netmap.c b/net/netmap.c
>> index 27295ab..6a4c01c 100644
>> --- a/net/netmap.c
>> +++ b/net/netmap.c
>> @@ -49,8 +49,12 @@ typedef struct NetmapState {
>>      bool                write_poll;
>>      struct iovec        iov[IOV_MAX];
>>      int                 vnet_hdr_len;  /* Current virtio-net header length. */
>> +    QTAILQ_ENTRY(NetmapState) next;
>>  } NetmapState;
>>
>> +static QTAILQ_HEAD(, NetmapState) netmap_clients =
>> +                   QTAILQ_HEAD_INITIALIZER(netmap_clients);
>> +
>>  #ifndef __FreeBSD__
>>  #define pkt_copy bcopy
>>  #else
>> @@ -78,6 +82,23 @@ pkt_copy(const void *_src, void *_dst, int l)
>>  #endif /* __FreeBSD__ */
>>
>>  /*
>> + * find nm_desc parent with same allocator
>> + */
>> +static struct nm_desc *
>> +netmap_find_memory(struct nm_desc *nmd)
>> +{
>> +    NetmapState *s;
>> +
>> +    QTAILQ_FOREACH(s, &netmap_clients, next) {
>> +        if (nmd->req.nr_arg2 == s->nmd->req.nr_arg2) {
>> +            return s->nmd;
>> +        }
>> +    }
>> +
>> +    return NULL;
>> +}
>> +
>> +/*
>>   * Open a netmap device. We assume there is only one queue
>>   * (which is the case for the VALE bridge).
>>   */
>> @@ -86,10 +107,11 @@ static struct nm_desc *netmap_open(const NetdevNetmapOptions *nm_opts,
>>  {
>>      struct nm_desc *nmd;
>>      struct nmreq req;
>> +    int ret;
>>
>>      memset(&req, 0, sizeof(req));
>>
>> -    nmd = nm_open(nm_opts->ifname, &req, NETMAP_NO_TX_POLL,
>> +    nmd = nm_open(nm_opts->ifname, &req, NETMAP_NO_TX_POLL | NM_OPEN_NO_MMAP,
>>                    NULL);
>>      if (nmd == NULL) {
>>          error_setg_errno(errp, errno, "Failed to nm_open() %s",
>> @@ -97,6 +119,17 @@ static struct nm_desc *netmap_open(const NetdevNetmapOptions *nm_opts,
>>          return NULL;
>>      }
>>
>> +    /* Check if we already have a nm_desc that uses the same memory as the one
>> +     * just opened, so that nm_mmap() can skip mmap() and inherit from parent.
>> +     */
>> +    ret = nm_mmap(nmd, netmap_find_memory(nmd));
>
> Looks like I could not find nm_mmap() definition in neither qemu or
> freebsd source. Is there anything missed?
>
>> +    if (ret) {
>> +        error_setg_errno(errp, errno, "Failed to nm_mmap() %s",
>> +                         nm_opts->ifname);
>> +        nm_close(nmd);
>> +        return NULL;
>> +    }
>> +
>>      return nmd;
>>  }
>>
>> @@ -321,6 +354,8 @@ static void netmap_cleanup(NetClientState *nc)
>>      netmap_poll(nc, false);
>>      nm_close(s->nmd);
>>      s->nmd = NULL;
>> +
>> +    QTAILQ_REMOVE(&netmap_clients, s, next);
>>  }
>>
>>  /* Offloading manipulation support callbacks. */
>> @@ -423,6 +458,7 @@ int net_init_netmap(const NetClientOptions *opts,
>>      s->rx = NETMAP_RXRING(nmd->nifp, 0);
>>      s->vnet_hdr_len = 0;
>>      pstrcpy(s->ifname, sizeof(s->ifname), netmap_opts->ifname);
>> +    QTAILQ_INSERT_TAIL(&netmap_clients, s, next);
>>      netmap_read_poll(s, true); /* Initially only poll for reads. */
>>
>>      return 0;
>



-- 
Vincenzo Maffione