Bug 1129259

Fix included in qemu-kvm-rhev-2.1.0-4.el7

 

Test on qemu-kvm-rhev-2.1.0-4.el7 version

I can find these traces about rng devices

#cat vim /usr/share/systemtap/tapset/qemu-kvm.stp
...

probe qemu.kvm.virtio_rng_guest_not_ready = process("/usr/libexec/qemu-kvm").mark("virtio_rng_guest_not_ready")
{
  rng = $arg1;
}
probe qemu.kvm.virtio_rng_pushed = process("/usr/libexec/qemu-kvm").mark("virtio_rng_pushed")
{
  rng = $arg1;
  len = $arg2;
}
probe qemu.kvm.virtio_rng_request = process("/usr/libexec/qemu-kvm").mark("virtio_rng_request")
{
  rng = $arg1;
  size = $arg2;
  quota = $arg3;
}

Test this bug as follow version:
Host:
# uname -r 
3.10.0-144.el7.x86_64
# rpm -q qemu-kvm-rhev
qemu-kvm-rhev-2.1.0-4.el7.x86_64

Guest :rhel7

Prepare script for virtio_rng device.

# cat qemu.kvm.virtio_rng_guest_not_ready
probe qemu.kvm.virtio_rng_guest_not_ready 

{
	 printf("rng=%d\n",rng);

}


# cat qemu.kvm.virtio_rng_pushed.stp
probe qemu.kvm.virtio_rng_pushed

{
		 printf("rng=%d\n",rng);
		 	  printf("len=%d\n",len);

}
# cat qemu.kvm.virtio_rng_request.stp
probe qemu.kvm.virtio_rng_request

{
		 printf("rng=%d\n",rng);
		 	  printf("size=%d\n",size);
			  	   printf("quota=%d\n",quota);

}


Steps
1.Boot guest with "-device virtio-rng-pci,max-bytes=1024,period=1000"

2.While booting guest ,execute scripts 
# stap qemu.kvm.virtio_rng_pushed.stp


#stap qemu.kvm.virtio_rng_request.stp

#stap qemu.kvm.virtio_rng_guest_not_ready


Results:
# stap qemu.kvm.virtio_rng_request.stp
rng=140713073408696
size=0
quota=1024
rng=140713073408696
size=0
quota=1024
rng=140713073408696
....
#stap qemu.kvm.virtio_rng_pushed.stp
rng=140713073408696
len=64
rng=140713073408696
len=64
rng=140713073408696
len=64
rng=140713073408696
len=64
rng=140713073408696
...

# stap qemu.kvm.virtio_rng_guest_not_ready 
rng=140713073408696
rng=140713073408696
rng=140713073408696
rng=140713073408696
rng=140713073408696
...



Hi,Amit
   Could we can verify this bug as above test? 

best regards
fang lang

You're seeing some values, which is fine, I guess.

A better test is to check against a known thing.  Like, with the new initial randomness patch in bug 1119299, you should see traces at guest bootup about virtio_rng_pushed.  With previous guest kernels, you should not see them.

Also, with the new khwrngd in bug 1129195, reading /dev/random should be much faster inside the guest, and show a lot of traces.  With previous kernels, reading from /dev/random in guest should not show traces.

Can you please check it that way?  In doing that, you will also be verifiying those other two bugs :)

(In reply to Amit Shah from comment #5)
> You're seeing some values, which is fine, I guess.
> 
> A better test is to check against a known thing.  Like, with the new initial
> randomness patch in bug 1119299, you should see traces at guest bootup about
> virtio_rng_pushed.  With previous guest kernels, you should not see them.
> 
Hi, Amit
   For comment4 test, i use the old kernel(guest:3.10.0-123.el7.x86_64) to test,that's mean i can get the traces on previous kernel.

Results:
stap qemu.kvm.virtio_rng_pushed.stp
rng=140094291921336
len=64
rng=140094291921336
len=64
rng=140094291921336
len=64
rng=140094291921336
len=64
rng=140094291921336
len=64
rng=140094291921336
len=64
...

> Also, with the new khwrngd in bug 1129195, reading /dev/random should be
> much faster inside the guest, and show a lot of traces.  With previous
> kernels, reading from /dev/random in guest should not show traces.
> 
> Can you please check it that way?  In doing that, you will also be
> verifiying those other two bugs :)

I test on previous kernel (guest:3.10.0-123.el7.x86_64),in guest ,do " dd if=/dev/random of=test bs=512 count=1000

# dd if=/dev/random of=test bs=512 count=10000 iflag=fullblock
10000+0 records in
10000+0 records out
5120000 bytes (5.1 MB) copied, 6.17742 s, 829 kB/s


Test on latest kernel(3.10.0-167.el7.x86_64)
#  dd if=/dev/random of=test bs=512 count=10000 iflag=fullblock
10000+0 records in
10000+0 records out
5120000 bytes (5.1 MB) copied, 5.40637 s, 947 kB/s

On latest kernel for guest , faster than previous kernel.

Anything i was wrong, please correct me .thanks

Please try with the default /dev/random device instead of urandom on host.

(In reply to Amit Shah from comment #7)
> Please try with the default /dev/random device instead of urandom on host.

Test this bug as follow version:
Host:
# uname -r
3.10.0-167.el7.x86_64
# rpm -q qemu-kvm-rhev
qemu-kvm-rhev-2.1.0-4.el7.x86_64

Guest: 3.10.0-167.el7.x86_64

Prepare:

# cat qemu.kvm.virtio_rng_pushed.stp 
probe qemu.kvm.virtio_rng_pushed

{
		 printf("rng=%d\n",rng);
		 	  printf("len=%d\n",len);

}


Steps:
1.#stap qemu.kvm.virtio_rng_pushed.stp

2.Boot guest with 
-object rng-random,id=rng0,filename=/dev/random -device virtio-rng-pci,rng=rng0  

3.After guest boot up ,dd in guest

# dd if=/dev/random of=test bs=512 count=10000 iflag=fullblock

Results:
On host:
#stap qemu.kvm.virtio_rng_pushed.stp
rng=139746200938936
len=64
rng=139746200938936
len=64
rng=139746200938936
len=64
rng=139746200938936
len=64
....

In guest:
# dd if=/dev/random of=test bs=512 count=10000 iflag=fullblock
10000+0 records in
10000+0 records out
5120000 bytes (5.1 MB) copied, 15.639 s, 327 kB/s


Test on old kernel version 

# uname -r
3.10.0-167.el7.x86_64
# rpm -q qemu-kvm-rhev
qemu-kvm-rhev-2.1.0-4.el7.x86_64

Guest: 3.10.0-123.el7.x86_64

Steps As same as above 

Results:
On Host:can get traces log

In guest:
#  dd if=/dev/random of=test bs=512 count=10000 iflag=fullblock
10000+0 records in
10000+0 records out
5120000 bytes (5.1 MB) copied, 16.3997 s, 312 kB/s


MY CLI:
 /usr/libexec/qemu-kvm -cpu SandyBridge -enable-kvm -m 4G -smp 4,sockets=1,cores=4,threads=1 -name test -rtc base=localtime,clock=host,driftfix=slew  -k en-us  -boot menu=on -vnc :3 -vga cirrus -usb -device usb-tablet -monitor stdio -drive file=/home/RHEL-Server-7.0-64-virtio.qcow2,if=none,id=drive-system-disk,media=disk,format=qcow2,aio=native,werror=stop,rerror=stop -device virtio-blk-pci,drive=drive-system-disk,id=system-disk,addr=0x3 -qmp unix:/tmp/q1,server,nowait -net none -object rng-random,id=rng0,filename=/dev/random -device virtio-rng-pci,rng=rng0  -netdev tap,id=hostnet0,vhost=on,script=/etc/qemu-ifup -device virtio-net-pci,netdev=hostnet0,id=vnet0,mac=52:54:00:1a:2b:02 -trace events=/flang/vrng-trace-events

<amit> what if you only use ssh?
<amit> ie no mouse and not much keyboard after starting the dd?
<amit> and you can use /dev/urandom for this test

*Test this bug as above request

Host:
# uname -r
3.10.0-167.el7.x86_64
# rpm -q qemu-kvm-rhev
qemu-kvm-rhev-2.1.0-4.el7.x86_64

Guest:RHEL7 

3.10.0-167.el7.x86_64

Steps:
1.Boot guest with 
...-object rng-random,id=rng0,filename=/dev/urandom -device virtio-rng-pci,rng=rng0...

2.After guest boot up ,ssh guest,then dd

# dd if=/dev/random of=test bs=512 count=10000 iflag=fullblock
10000+0 records in
10000+0 records out
5120000 bytes (5.1 MB) copied, 3.37219 s, 1.5 MB/s


*Test on old kernel
# uname -r
3.10.0-167.el7.x86_64
# rpm -q qemu-kvm-rhev
qemu-kvm-rhev-2.1.0-4.el7.x86_64

Guest:
3.10.0-123.el7.x86_64

Steps as same as above

Results:
IN guest:

# dd if=/dev/random of=test bs=512 count=10000 iflag=fullblock
10000+0 records in
10000+0 records out
5120000 bytes (5.1 MB) copied, 4.48857 s, 1.1 MB/s

Hi Amit
   QE set this bz as verified first. Detailed reasons as below:
   1.Current, with my understanding, 3 bzs(this bug,bug1119299,bug1129195)  involved in the rng device issue,With my understing.This bz is mainly focus on traces events.The others not only focus on traces.
   2.This bug is 'qemu-kvm-rhev' component bug,not depend on bugs. The other two are 'kernel' bugs.

   Amit,what's your option, do you want to let QE keep all these 3 bzs on qa status then verify it together finally or you want to verify this bug first,then test other two?


thanks 
fang lang

Yes, this is fine.

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHSA-2015-0624.html