From mboxrd@z Thu Jan  1 00:00:00 1970
From: Thomas Kittel <kittel@in.tum.de>
Subject: KVM freeze when using --serial
Date: Wed, 07 Apr 2010 16:32:33 +0200
Message-ID: <4BBC9781.6030705@in.tum.de>
Mime-Version: 1.0
Content-Type: multipart/mixed;
 boundary="------------020306090504030903030509"
Cc: qemu-devel@nongnu.org
To: kvm@vger.kernel.org
Return-path: <kvm-owner@vger.kernel.org>
Received: from atlas.fs.tum.de ([129.187.202.11]:44151 "EHLO atlas.fs.tum.de"
	rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
	id S932604Ab0DGOjB (ORCPT <rfc822;kvm@vger.kernel.org>);
	Wed, 7 Apr 2010 10:39:01 -0400
Sender: kvm-owner@vger.kernel.org
List-ID: <kvm.vger.kernel.org>

This is a multi-part message in MIME format.
--------------020306090504030903030509
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 8bit

Hi there,

I already posted this problem to #kvm on freenode.

Please set me in CC: when replying to this mail, as I am not subscribed 
to this mailing lists right now.

The Scenario is as follows:

I got 2 VM processes in userspace.

The first is started with the parameter --monitor pty.
    => This results in a file /dev/pts/x in the host,
        (crw--w---- 1 kittel tty 136, 3 2010-04-07 15:51 /dev/pts/3 on 
my system)

Another VM is then started with the parameter --serial /dev/pts/3
    => This results in /dev/ttyS0 inside the second VM.

Both VMs are running debian lenny. The host (debian) uses qemu-kvm 0.12.3.
"startvms.sh start" is used to start the VMs.

Running the executable build from test.c in the second VM results in a 
freeze of this VM.
(The test.c included uses /dev/ttyS1 as /dev/ttyS0 is the VMs serial 
console in my setup.)
The process uses 100% CPU and is stuck in kvm_mutex_lock().

Trying to use the build in gdbserver didnīt work because it also locked.

Is there a way to tunnel one VMs monitor console to another VM?

Thanks Thomas





--------------020306090504030903030509
Content-Type: text/x-csrc;
 name="test.c"
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="test.c"

#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>

#include <signal.h>

#include <pthread.h>

void signal_handler(int signum){
	pthread_exit(NULL);
}

void *readFile(void * ptr){
	signal(SIGTERM, signal_handler);
	int fd;
	char buffer;
	fd = open("/dev/ttyS1", O_RDONLY);
	while(true){
		read(fd, &buffer, 1);
		printf("%c", buffer);
		fflush(stdout);
	}

	close(fd);
	pthread_exit(NULL);

}

int main(int argc, char** argv){
	pthread_t thread;

	pthread_create(&thread, NULL, &readFile, NULL);

	sleep(10);
		
	pthread_kill(thread, SIGTERM);
	pthread_join(thread, NULL);

}
	

--------------020306090504030903030509
Content-Type: application/x-sh;
 name="startvms.sh"
Content-Transfer-Encoding: 7bit
Content-Disposition: inline;
 filename="startvms.sh"

#!/bin/sh


case $1 in 
  start)
    KVM1="kvm -name ROOTKITVM -m 512 -hda rootkitvm/rootkitvm -serial pty -monitor pty -mem-path /tmp -mem-prealloc -pidfile rootkitvm/pid -daemonize"

    PTS1=`$KVM1 2>&1 | grep pts | awk '{ print $5 }' &`

    sleep 1
    ROOTKITVMPID=`cat rootkitvm/pid`

    echo "Started Rootkit VM. PID = $ROOTKITVMPID"

    # RAMFILE=`ls -laF /tmp/kvm.$ROOTKITVMPID.* | sort | tail - -n1 | awk '{ print $8 }'`

    KVM2="kvm -name IDSVM -m 512 -hda idsvm/idsvm  -hdb rootkitvm/rootkitvm --serial pty"

    for i in $PTS1
    do
      KVM2="$KVM2 --serial $i "
    done

    # KVM2="$KVM2 --drive file=$RAMFILE,if=virtio"
    
		KVM2="$KVM2 -pidfile idsvm/pid -daemonize"

    PTS2=`$KVM2 2>&1 | grep pts | awk '{ print $5 }' &`

    echo "IDSVM Serial is $PTS2"

    sleep 1

    IDSVMPID=`cat idsvm/pid`

    echo "Started IDS VM. PID = $IDSVMPID"
    ;;
  stop)
    ROOTKITVMPID=`cat rootkitvm/pid`
    kill -9 $ROOTKITVMPID
    rm -rf /tmp/kvm.$ROOTKITVMPID.*
    IDSVMPID=`cat idsvm/pid`
    kill -9 $IDSVMPID
    rm -rf /tmp/kvm.$IDSVMPID.*
    ;;
  restart)
    $0 stop
    sleep 2
    $0 start
    ;;
  *)
    echo "No command given"
    ;;

esac

--------------020306090504030903030509--