[PATCHv9 3/4] libibverbs: Add API to resolve GID to L2 address

[PATCHv9 3/4] libibverbs: Add API to resolve GID to L2 address

[Eli Cohen]

Add a new API, resolve_eth_gid(), which resolves a GID to layer 2 address
information. A GID resembles an IPv6 link local address and encodes the MAC
address and the VLAN tag within it. The function accepts the destination GID,
port number and source GID index and returns the MAC, VLAN and indications
whether the remote address is tagged VLAN and whether the address is multicast.

VLAN encoding is done as follows:
gid[11] is MS byte
gid[12] is LS byte

Signed-off-by: Eli Cohen <eli-VPRAkNaXOzVS1MOuV/RT9w@public.gmane.org>
---

Changes from V8:
1. Move resolving of GID to MAC from kernel space to user space.

 include/infiniband/driver.h |    7 +++
 src/verbs.c                 |   97 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 104 insertions(+), 0 deletions(-)

diff --git a/include/infiniband/driver.h b/include/infiniband/driver.h
index 9a81416..be4ec98 100644
--- a/include/infiniband/driver.h
+++ b/include/infiniband/driver.h
@@ -37,6 +37,8 @@
 
 #include <infiniband/verbs.h>
 #include <infiniband/kern-abi.h>
+#include <arpa/inet.h>
+#include <string.h>
 
 #ifdef __cplusplus
 #  define BEGIN_C_DECLS extern "C" {
@@ -143,4 +145,9 @@ const char *ibv_get_sysfs_path(void);
 int ibv_read_sysfs_file(const char *dir, const char *file,
 			char *buf, size_t size);
 
+int resolve_eth_gid(struct ibv_pd *pd, uint8_t port_num,
+		    union ibv_gid *dgid, uint8_t sgid_index,
+		    uint8_t mac[], uint16_t *vlan, uint8_t *tagged,
+		    uint8_t *is_mcast);
+
 #endif /* INFINIBAND_DRIVER_H */
diff --git a/src/verbs.c b/src/verbs.c
index ba3c0a4..272feac 100644
--- a/src/verbs.c
+++ b/src/verbs.c
@@ -148,6 +148,7 @@ struct ibv_pd *__ibv_alloc_pd(struct ibv_context *context)
 }
 default_symver(__ibv_alloc_pd, ibv_alloc_pd);
 
+
 int __ibv_dealloc_pd(struct ibv_pd *pd)
 {
 	return pd->context->ops.dealloc_pd(pd);
@@ -543,3 +544,99 @@ int __ibv_detach_mcast(struct ibv_qp *qp, const union ibv_gid *gid, uint16_t lid
 	return qp->context->ops.detach_mcast(qp, gid, lid);
 }
 default_symver(__ibv_detach_mcast, ibv_detach_mcast);
+
+static uint16_t get_vlan_id(const union ibv_gid *dgid)
+{
+	return dgid->raw[11] << 8 | dgid->raw[12];
+}
+
+static void get_ll_mac(const union ibv_gid *gid, uint8_t *mac)
+{
+	memcpy(mac, &gid->raw[8], 3);
+	memcpy(mac + 3, &gid->raw[13], 3);
+	mac[0] ^= 2;
+}
+
+static int is_multicast_gid(const union ibv_gid *gid)
+{
+	return gid->raw[0] == 0xff;
+}
+
+static void get_mcast_mac(const union ibv_gid *gid, uint8_t *mac)
+{
+	int i;
+
+	mac[0] = 0x33;
+	mac[1] = 0x33;
+	for (i = 2; i < 6; ++i)
+		mac[i] = gid->raw[i + 10];
+}
+
+static int is_link_local_gid(const union ibv_gid *gid)
+{
+	uint32_t hi = *(uint32_t *)(gid->raw);
+	uint32_t lo = *(uint32_t *)(gid->raw + 4);
+	if (hi == htonl(0xfe800000) && lo == 0)
+		return 1;
+
+	return 0;
+}
+
+static int resolve_gid(const union ibv_gid *dgid, uint8_t *mac, uint8_t *is_mcast)
+{
+	if (is_link_local_gid(dgid)) {
+		get_ll_mac(dgid, mac);
+		*is_mcast = 0;
+	} else if (is_multicast_gid(dgid)) {
+		get_mcast_mac(dgid, mac);
+		*is_mcast = 1;
+	} else
+		return -EINVAL;
+
+	return 0;
+}
+
+static int is_tagged_vlan(const union ibv_gid *gid)
+{
+	uint16_t tag;
+
+	tag = gid->raw[11] << 8 |  gid->raw[12];
+
+	return tag < 0x1000;
+}
+
+int __resolve_eth_gid(struct ibv_pd *pd, uint8_t port_num,
+		      const union ibv_gid *dgid, uint8_t sgid_index,
+		      uint8_t mac[], uint16_t *vlan, uint8_t *tagged,
+		      uint8_t *is_mcast)
+{
+	int err;
+	union ibv_gid sgid;
+	int stagged, svlan;
+
+	err = resolve_gid(dgid, mac, is_mcast);
+	if (err)
+		return err;
+
+	err = ibv_query_gid(pd->context, port_num, sgid_index, &sgid);
+	if (err)
+		return err;
+
+	stagged = is_tagged_vlan(&sgid);
+	if (stagged) {
+		if (!is_tagged_vlan(dgid))
+			return -1;
+
+		svlan = get_vlan_id(&sgid);
+		if (svlan != get_vlan_id(dgid))
+			return -1;
+
+		*tagged = 1;
+		*vlan = svlan;
+	} else
+		*tagged = 0;
+
+	return 0;
+}
+default_symver(__resolve_eth_gid, resolve_eth_gid);
+
-- 
1.7.2

--
To unsubscribe from this list: send the line "unsubscribe linux-rdma" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCHv9 3/4] libibverbs: Add API to resolve GID to L2 address

[Jason Gunthorpe]

On Fri, Aug 06, 2010 at 05:43:37PM +0300, Eli Cohen wrote:

> +int resolve_eth_gid(struct ibv_pd *pd, uint8_t port_num,
> +		    union ibv_gid *dgid, uint8_t sgid_index,
> +		    uint8_t mac[], uint16_t *vlan, uint8_t *tagged,
> +		    uint8_t *is_mcast);

Still missing the const on dgid

It also just occured to me that this should be ibv_resolve_eth_gid to
keep within the symbol namespace prefix used by libibverbs.

Jason
--
To unsubscribe from this list: send the line "unsubscribe linux-rdma" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCHv9 3/4] libibverbs: Add API to resolve GID to L2 address

[Eli Cohen]

On Fri, Aug 06, 2010 at 10:45:52AM -0600, Jason Gunthorpe wrote:
> On Fri, Aug 06, 2010 at 05:43:37PM +0300, Eli Cohen wrote:
> 
> > +int resolve_eth_gid(struct ibv_pd *pd, uint8_t port_num,
> > +		    union ibv_gid *dgid, uint8_t sgid_index,
> > +		    uint8_t mac[], uint16_t *vlan, uint8_t *tagged,
> > +		    uint8_t *is_mcast);
> 
> Still missing the const on dgid

OK, I failed to use const in the prototype of the function. I am just
curios why is it necessary at all? The are many places where you pass
a pointer to struct that is not meant to be changed and you do not use
const. For example, ibv_create_ah() passes as the first parameter a
pointer to a struct ibv_pd and does not use const.

> 
> It also just occured to me that this should be ibv_resolve_eth_gid to
> keep within the symbol namespace prefix used by libibverbs.
> 
That was deliberate. Since it is meant to be used by the hardware
level libraries only I did not use the the ibv_ prefix but it I don't
have a strong opinion about this so I will change it anyway.
--
To unsubscribe from this list: send the line "unsubscribe linux-rdma" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html