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Re: [Qemu-devel] [PATCH 1/1] Migration: libvirt live migration over RDMA
From: |
Dr. David Alan Gilbert |
Subject: |
Re: [Qemu-devel] [PATCH 1/1] Migration: libvirt live migration over RDMA of ipv6 addr failed |
Date: |
Tue, 24 Jan 2017 17:36:39 +0000 |
User-agent: |
Mutt/1.7.1 (2016-10-04) |
* David Dai (address@hidden) wrote:
> Using libvirt to do live migration over RDMA via ip v6 address failed.
> For example:
> # virsh migrate --live --migrateuri rdma://[deba::2222]:49152 \
> rhel73_host1_guest1 qemu+ssh://[deba::2222]/system --verbose
> address@hidden::2222's password:
> error: internal error: unable to execute QEMU command 'migrate': RDMA ERROR:
> could not rdma_getaddrinfo address deba
>
> As we can see, the ip v6 address used by rdma_getaddrinfo() has only "deba"
> part. It should be "deba::2222".
>
> 1) According to rfc 3986, a literal ip v6 address should be enclosed
> in '[' and ']'.
> When using virsh command to do live migration via ip v6 addresss, user
> will input the ip v6 address with brackets (i.e. rdma://[deba::2222]:49152).
> libvirt will parse command line option by calling virURIParse().
> Inside it calls virStringStripIPv6Brackets() to strip off the brackets.
> The uri passed in to virURIParse() is:
> "uri = rdma://[deba::2222]:49152"
> Inside virURIParse() routine, it will strip off the bracket '[' and ']' if
> it's ip v6 address. Then save the ip v6 address in this format "deba::2222"
> in the virURI->server field, and to be passed to qemu.
>
> 2) At the beginning of migration, in qemu's qemu_rdma_data_init(host_port)
> routine, it calls inet_parse(host_port) routine to parse the ip v6 address
> and
> port string obtained from libvirt.
> The input string host_port passed to qemu_rdma_data_init() can be:
> "hostname:port", or
> "ipv4address:port", or
> "[ipv6address]:port" (i.e "[deba::2222]:49152"), or
> "ipv6address:port" (i.e "deba::2222:49152").
Hi David,
I'm ccing in some libvirt guys here; this might be a bug that
libvirt should be leaving the []'s on when it calls qemu.
Lets just check with Jiri and Dan (who I've added to the mail) to see what
they thing libvirt should be doing here.
Dave
> Existing qemu api inet_parse() can handle the above first 3 cases properly,
> but didn't handle the last case ("ipv6address:port") correctly.
> In this live migration over rdma via ip v6 address case, the server ip v6
> address obtained from libvirt doesn't contain the brackets '[' and ']'
> (i.e. "deba::2222:49152"). It caused inet_parse() to parse only "deba" part,
> and stopped at the 1st colon ':'. As the result, the subsequent
> rdma_getaddrinfo() with ip address "deba" will fail.
>
> If we don't strip off brackets '[' and ']' for an ip v6 address in libvirt's
> virURIParse(), it will cause libvirt ipv6 ssh authentication failure.
>
> NOTE:
> If using libvirt to do live migration over TCP via ip v6 address:
> # virsh migrate --live --migrateuri tcp://[deba::2222]:49152 \
> rhel73_host1_guest1 qemu+ssh://[deba::2222]/system --verbose
> It works fine.
> In migrateuri of tcp case, libvirt will call virNetSocketNewConnectTCP()
> directly to connect to remote "deba::2222:49152" after it strips off
> the bracket '[' and ']' for an ip v6 address.
> On qemu side, fd_start_outgoing_migration() will be called to do migration.
> It doesn't call inet_parse(). So we don't see issue in tcp case.
>
> Solution:
> I choose to fix the code in qemu's inet_parse() routine to parse the
> ip v6 addresss w/o brackets properly (i.e. "deba::2222:49152" format).
>
> Signed-off-by: David Dai <address@hidden>
> ---
> util/qemu-sockets.c | 28 +++++++++++++++++++++++-----
> 1 files changed, 23 insertions(+), 5 deletions(-)
>
> diff --git a/util/qemu-sockets.c b/util/qemu-sockets.c
> index 7c120c4..e09191c 100644
> --- a/util/qemu-sockets.c
> +++ b/util/qemu-sockets.c
> @@ -584,6 +584,8 @@ InetSocketAddress *inet_parse(const char *str, Error
> **errp)
> char port[33];
> int to;
> int pos;
> + char *first_col_p = strchr(str, ':');
> + char *last_col_p = strrchr(str, ':');
>
> addr = g_new0(InetSocketAddress, 1);
>
> @@ -595,11 +597,27 @@ InetSocketAddress *inet_parse(const char *str, Error
> **errp)
> error_setg(errp, "error parsing port in address '%s'", str);
> goto fail;
> }
> - } else if (str[0] == '[') {
> - /* IPv6 addr */
> - if (sscanf(str, "[%64[^]]]:%32[^,]%n", host, port, &pos) != 2) {
> - error_setg(errp, "error parsing IPv6 address '%s'", str);
> - goto fail;
> + } else if (first_col_p != last_col_p) {
> + if (str[0] != '[') {
> + /* IPv6 addr w/o brackets */
> + char *port_p;
> + char *comma_p;
> +
> + pstrcpy(host, sizeof(host), str);
> + port_p = strrchr(host, ':');
> + *port_p++ = '\0';
> + pstrcpy(port, sizeof(port), port_p);
> + comma_p = strchr(port, ',');
> + if (comma_p != NULL) {
> + *comma_p = '\0';
> + }
> + pos = strlen(host) + strlen(port) + 1;
> + } else {
> + /* IPv6 addr with brackets */
> + if (2 != sscanf(str, "[%64[^]]]:%32[^,]%n", host, port, &pos)) {
> + error_setg(errp, "error parsing IPv6 address '%s'", str);
> + goto fail;
> + }
> }
> addr->ipv6 = addr->has_ipv6 = true;
> } else {
> --
> 1.7.1
>
>
--
Dr. David Alan Gilbert / address@hidden / Manchester, UK