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migration/rdma: Remove qemu_rdma_broken_ipv6_kernel

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I hit following error which testing migration in pure RoCE env:
"-incoming rdma:[::]:8089: RDMA ERROR: You only have RoCE / iWARP devices in your
systems and your management software has specified '[::]', but IPv6 over RoCE /
iWARP is not supported in Linux.#012'."

In our setup, we use rdma bind on ipv6 on target host, while connect from source
with ipv4, remove the qemu_rdma_broken_ipv6_kernel, migration just work
fine.

Checking the git history, the function was added since introducing of
rdma migration, which is more than 10 years ago. linux-rdma has
improved support on RoCE/iWARP for ipv6 over past years. There are a few fixes
back in 2016 seems related to the issue, eg:
aeb76df46d11 ("IB/core: Set routable RoCE gid type for ipv4/ipv6 networks")

other fixes back in 2018, eg:
052eac6eeb56 RDMA/cma: Update RoCE multicast routines to use net namespace
8d20a1f0ecd5 RDMA/cma: Fix rdma_cm raw IB path setting for RoCE
9327c7afdce3 RDMA/cma: Provide a function to set RoCE path record L2 parameters
5c181bda77f4 RDMA/cma: Set default GID type as RoCE when resolving RoCE route
3c7f67d1880d IB/cma: Fix default RoCE type setting
be1d325a3358 IB/core: Set RoCEv2 MGID according to spec
63a5f483af0e IB/cma: Set default gid type to RoCEv2

So remove the outdated function and it's usage.

Cc: Peter Xu <peterx@redhat.com>
Cc: Li Zhijian <lizhijian@fujitsu.com>
Cc: Yu Zhang <yu.zhang@ionos.com>
Cc: Fabiano Rosas <farosas@suse.de>
Cc: qemu-devel@nongnu.org
Cc: linux-rdma@vger.kernel.org
Cc: michael@flatgalaxy.com
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
Tested-by: Li zhijian <lizhijian@fujitsu.com>
Reviewed-by: Michael Galaxy <mrgalaxy@nvidia.com>
Link: https://lore.kernel.org/r/20250402051306.6509-1-jinpu.wang@ionos.com
[peterx: some cosmetic changes]
Signed-off-by: Peter Xu <peterx@redhat.com>
This commit is contained in:
Jack Wang 2025-04-02 07:13:06 +02:00 • committed by Peter Xu
parent 20d8262281
commit 0bafd6e9cb
1 changed files with 4 additions and 176 deletions
Download patch file Download diff file Expand all files Collapse all files

180
migration/rdma.c
View file

@ -767,149 +767,6 @@ static void qemu_rdma_dump_gid(const char *who, struct rdma_cm_id *id)
trace_qemu_rdma_dump_gid(who, sgid, dgid);
}
/*
* As of now, IPv6 over RoCE / iWARP is not supported by linux.
* We will try the next addrinfo struct, and fail if there are
* no other valid addresses to bind against.
*
* If user is listening on '[::]', then we will not have a opened a device
* yet and have no way of verifying if the device is RoCE or not.
*
* In this case, the source VM will throw an error for ALL types of
* connections (both IPv4 and IPv6) if the destination machine does not have
* a regular infiniband network available for use.
*
* The only way to guarantee that an error is thrown for broken kernels is
* for the management software to choose a *specific* interface at bind time
* and validate what time of hardware it is.
*
* Unfortunately, this puts the user in a fix:
*
* If the source VM connects with an IPv4 address without knowing that the
* destination has bound to '[::]' the migration will unconditionally fail
* unless the management software is explicitly listening on the IPv4
* address while using a RoCE-based device.
*
* If the source VM connects with an IPv6 address, then we're OK because we can
* throw an error on the source (and similarly on the destination).
*
* But in mixed environments, this will be broken for a while until it is fixed
* inside linux.
*
* We do provide a *tiny* bit of help in this function: We can list all of the
* devices in the system and check to see if all the devices are RoCE or
* Infiniband.
*
* If we detect that we have a *pure* RoCE environment, then we can safely
* thrown an error even if the management software has specified '[::]' as the
* bind address.
*
* However, if there is are multiple hetergeneous devices, then we cannot make
* this assumption and the user just has to be sure they know what they are
* doing.
*
* Patches are being reviewed on linux-rdma.
*/
static int qemu_rdma_broken_ipv6_kernel(struct ibv_context *verbs, Error **errp)
{
/* This bug only exists in linux, to our knowledge. */
#ifdef CONFIG_LINUX
struct ibv_port_attr port_attr;
/*
* Verbs are only NULL if management has bound to '[::]'.
*
* Let's iterate through all the devices and see if there any pure IB
* devices (non-ethernet).
*
* If not, then we can safely proceed with the migration.
* Otherwise, there are no guarantees until the bug is fixed in linux.
*/
if (!verbs) {
int num_devices;
struct ibv_device **dev_list = ibv_get_device_list(&num_devices);
bool roce_found = false;
bool ib_found = false;
for (int x = 0; x < num_devices; x++) {
verbs = ibv_open_device(dev_list[x]);
/*
* ibv_open_device() is not documented to set errno. If
* it does, it's somebody else's doc bug. If it doesn't,
* the use of errno below is wrong.
* TODO Find out whether ibv_open_device() sets errno.
*/
if (!verbs) {
if (errno == EPERM) {
continue;
} else {
error_setg_errno(errp, errno,
"could not open RDMA device context");
return -1;
}
}
if (ibv_query_port(verbs, 1, &port_attr)) {
ibv_close_device(verbs);
error_setg(errp,
"RDMA ERROR: Could not query initial IB port");
return -1;
}
if (port_attr.link_layer == IBV_LINK_LAYER_INFINIBAND) {
ib_found = true;
} else if (port_attr.link_layer == IBV_LINK_LAYER_ETHERNET) {
roce_found = true;
}
ibv_close_device(verbs);
}
if (roce_found) {
if (ib_found) {
warn_report("migrations may fail:"
" IPv6 over RoCE / iWARP in linux"
" is broken. But since you appear to have a"
" mixed RoCE / IB environment, be sure to only"
" migrate over the IB fabric until the kernel "
" fixes the bug.");
} else {
error_setg(errp, "RDMA ERROR: "
"You only have RoCE / iWARP devices in your systems"
" and your management software has specified '[::]'"
", but IPv6 over RoCE / iWARP is not supported in Linux.");
return -1;
}
}
return 0;
}
/*
* If we have a verbs context, that means that some other than '[::]' was
* used by the management software for binding. In which case we can
* actually warn the user about a potentially broken kernel.
*/
/* IB ports start with 1, not 0 */
if (ibv_query_port(verbs, 1, &port_attr)) {
error_setg(errp, "RDMA ERROR: Could not query initial IB port");
return -1;
}
if (port_attr.link_layer == IBV_LINK_LAYER_ETHERNET) {
error_setg(errp, "RDMA ERROR: "
"Linux kernel's RoCE / iWARP does not support IPv6 "
"(but patches on linux-rdma in progress)");
return -1;
}
#endif
return 0;
}
/*
* Figure out which RDMA device corresponds to the requested IP hostname
* Also create the initial connection manager identifiers for opening
@ -917,7 +774,6 @@ static int qemu_rdma_broken_ipv6_kernel(struct ibv_context *verbs, Error **errp)
*/
static int qemu_rdma_resolve_host(RDMAContext *rdma, Error **errp)
{
Error *err = NULL;
int ret;
struct rdma_addrinfo *res;
char port_str[16];
@ -953,9 +809,8 @@ static int qemu_rdma_resolve_host(RDMAContext *rdma, Error **errp)
goto err_resolve_get_addr;
}
/* Try all addresses, saving the first error in @err */
/* Try all addresses, exit loop on first success of resolving address */
for (struct rdma_addrinfo *e = res; e != NULL; e = e->ai_next) {
Error **local_errp = err ? NULL : &err;
inet_ntop(e->ai_family,
&((struct sockaddr_in *) e->ai_dst_addr)->sin_addr, ip, sizeof ip);
@ -964,25 +819,12 @@ static int qemu_rdma_resolve_host(RDMAContext *rdma, Error **errp)
ret = rdma_resolve_addr(rdma->cm_id, NULL, e->ai_dst_addr,
RDMA_RESOLVE_TIMEOUT_MS);
if (ret >= 0) {
if (e->ai_family == AF_INET6) {
ret = qemu_rdma_broken_ipv6_kernel(rdma->cm_id->verbs,
local_errp);
if (ret < 0) {
continue;
}
}
error_free(err);
goto route;
}
}
rdma_freeaddrinfo(res);
if (err) {
error_propagate(errp, err);
} else {
error_setg(errp, "RDMA ERROR: could not resolve address %s",
rdma->host);
}
error_setg(errp, "RDMA ERROR: could not resolve address %s", rdma->host);
goto err_resolve_get_addr;
route:
@ -2611,7 +2453,6 @@ err_rdma_source_connect:
static int qemu_rdma_dest_init(RDMAContext *rdma, Error **errp)
{
Error *err = NULL;
int ret;
struct rdma_cm_id *listen_id;
char ip[40] = "unknown";
@ -2661,9 +2502,8 @@ static int qemu_rdma_dest_init(RDMAContext *rdma, Error **errp)
goto err_dest_init_bind_addr;
}
/* Try all addresses, saving the first error in @err */
/* Try all addresses */
for (e = res; e != NULL; e = e->ai_next) {
Error **local_errp = err ? NULL : &err;
inet_ntop(e->ai_family,
&((struct sockaddr_in *) e->ai_dst_addr)->sin_addr, ip, sizeof ip);
@ -2672,24 +2512,12 @@ static int qemu_rdma_dest_init(RDMAContext *rdma, Error **errp)
if (ret < 0) {
continue;
}
if (e->ai_family == AF_INET6) {
ret = qemu_rdma_broken_ipv6_kernel(listen_id->verbs,
local_errp);
if (ret < 0) {
continue;
}
}
error_free(err);
break;
}
rdma_freeaddrinfo(res);
if (!e) {
if (err) {
error_propagate(errp, err);
} else {
error_setg(errp, "RDMA ERROR: Error: could not rdma_bind_addr!");
}
error_setg(errp, "RDMA ERROR: Error: could not rdma_bind_addr!");
goto err_dest_init_bind_addr;
}