[Pkg-xen-devel] Bug#744159: HVM guest can't be saved/migrated with xl

[Matyas Koszik]

Package: xen-utils-4.1
Version: 4.1.4-3+deb7u1
Severity: normal

It seems to be impossible to save or migrate HVM guest using the xl
toolstack. Trying to do so hangs the process initiating the action, and
the domU can't be shut down with the 'xl shutdown' command after this.
'xl destroy' works. The domain keeps running during the save operation,
doesn't get paused for any noticeable time and keeps running fine after
that.

The savefile contains nothing after the configuration dump, which is as
follows:

kernel = '/usr/lib/xen/boot/hvmloader'
builder='hvm'
device_model = '/usr/lib/xen/bin/qemu-dm'
vnclisten="0.0.0.0:6369"
vncpasswd="x"
memory = 256
name = "x"
vcpus = 1
vif = [ 'vifname=x,mac=00:16:3e:00:01:0d,ip=x' ]
disk = [ 'phy:x,hda,w', ]



Stracing xl save revealed where it blocks:

[...]
open("x.sav", O_WRONLY|O_CREAT|O_TRUNC, 0644) = 6
write(6, "Xen saved domain, xl format\n \0 \r"..., 48) = 48
write(6, "\231\1\0\0\nkernel = '/usr/lib/xen/boot"..., 413) = 413
write(2, "Saving to x.sav new xl form"..., 54) = 54
ioctl(3, SNDCTL_DSP_RESET, 0x7fffeea162a0) = 0
open("/dev/xen/evtchn", O_RDWR)         = 7
stat("/var/run/xenstored/socket", {st_mode=S_IFSOCK|0600, st_size=0, ...}) = 0
socket(PF_FILE, SOCK_STREAM, 0)         = 9
fcntl(9, F_GETFD)                       = 0
fcntl(9, F_SETFD, FD_CLOEXEC)           = 0
connect(9, {sa_family=AF_FILE, path="/var/run/xenstored/socket"}, 110) = 0
rt_sigaction(SIGPIPE, {SIG_IGN, [], SA_RESTORER, 0x7f696e28a4f0}, {SIG_DFL, [], SA_RESTORER, 0x7f696e28a4f0}, 8) = 0
write(9, "\2\0\0\0\0\0\0\0\0\0\0\0.\0\0\0", 16) = 16
write(9, "/local/domain/46/device/suspend/"..., 46) = 46
read(9, "\2\0\0\0\0\0\0\0\0\0\0\0\1\0\0\0", 16) = 16
read(9, "5", 1)                         = 1
rt_sigaction(SIGPIPE, {SIG_DFL, [], SA_RESTORER, 0x7f696e28a4f0}, NULL, 8) = 0
close(9)                                = 0
umask(022)                              = 022
open("/var/lib/xen/suspend_evtchn_46_lock.d", O_RDWR|O_CREAT|O_EXCL, 0666) = 9
umask(022)                              = 022
write(9, "     16096", 10)              = 10
close(9)                                = 0
ioctl(7, EVIOCGVERSION, 0x7fffeea16320) = 56
ioctl(3, SNDCTL_DSP_RESET, 0x7fffeea16260) = 0
read(7, "8\0\0\0", 4)                   = 4
write(7, "8\0\0\0", 4)                  = 4
mmap(NULL, 16781312, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f696c3c8000
ioctl(3, SNDCTL_DSP_RESET, 0x7fffeea11b50) = 0
ioctl(3, SNDCTL_DSP_RESET, 0x7fffeea11b50) = 0
ioctl(3, SNDCTL_DSP_RESET, 0x7fffeea11b50) = 2162688
ioctl(3, SNDCTL_DSP_RESET, 0x7fffeea11f00) = 0
ioctl(3, SNDCTL_DSP_RESET, 0x7fffeea11ab0) = 0
ioctl(3, SNDCTL_DSP_RESET, 0x7fffeea11b40) = 1048575
ioctl(3, SNDCTL_DSP_RESET, 0x7fffeea11a70) = 0
ioctl(3, SNDCTL_DSP_RESET, 0x7fffeea11a70) = 0
ioctl(7, EVIOCGKEYCODE or EVIOCSKEYCODE, 0x7fffeea11ac0) = 0
read(7, 0x7fffeea11aac, 4)              = ? ERESTARTSYS (To be restarted)
--- SIGINT (Interrupt) @ 0 (0) ---
+++ killed by SIGINT +++