Bug 1785091

Summary:	RFE: Support new rng backend model 'builtin'
Product:	Red Hat Enterprise Linux Advanced Virtualization	Reporter:	Yanqiu Zhang <yanqzhan>
Component:	libvirt	Assignee:	Michal Privoznik <mprivozn>
Status:	CLOSED ERRATA	QA Contact:	Yanqiu Zhang <yanqzhan>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	8.2	CC:	chhu, dyuan, hhan, jdenemar, jsuchane, lmen, mprivozn, o.freyermuth, xuzhang, yanqzhan, yduan
Target Milestone:	rc	Keywords:	FutureFeature, Triaged, Upstream
Target Release:	8.0	Flags:	jsuchane: mirror+
Hardware:	x86_64
OS:	Linux
Whiteboard:
Fixed In Version:	libvirt-6.2.0-1.el8	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2020-11-17 17:46:15 UTC	Type:	Feature Request
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	1689946
Bug Blocks:

Description Yanqiu Zhang 2019-12-19 06:19:56 UTC

Description of problem:
To align with qemu update of bz1689946, libvirt should support new rng backend model 'builtin'.

Version-Release number of selected component (if applicable):
libvirt-5.10.0-1.module+el8.2.0+5135+ed3b2489.x86_64
qemu-kvm-4.2.0-4.module+el8.2.0+5220+e82621dc.x86_64

How reproducible:
100%

Steps to Reproduce:
1. # cat /var/cache/libvirt/qemu/capabilities/3c76bc41d59c0c7314b1ae8e63f4f765d2cf16abaeea081b3ca1f5d8732f7bb1.xml |grep rng
  <flag name='virtio-rng'/>
  <flag name='rng-random'/>
  <flag name='rng-egd'/>

2.  Try to edit guest with rng-builtin:
  <rng model='virtio'>
      <backend model='builtin'/>
    </rng>
# virsh edit yqz82
error: XML document failed to validate against schema: Unable to validate doc against /usr/share/libvirt/schemas/domain.rng
Extra element devices in interleave
Element domain failed to validate content

Failed. Try again? [y,n,i,f,?]: 

Actual results:


Expected results:


Additional info:

Comment 1 Han Han 2020-01-01 05:09:16 UTC

Patches: https://www.redhat.com/archives/libvir-list/2020-January/msg00000.html

Comment 2 Michal Privoznik 2020-01-24 16:13:34 UTC

I've pushed patches upstream:

51489b8419 news: Update news for rng backend type builtin
bd51f89c30 qemu: Implement builtin rng backend
6a6d00e168 conf: Add rng backend model builtin
1bd17918b6 util: Do not assume comma after object id
9378713f56 qemu_capabilities: Introduce QEMU_CAPS_OBJECT_RNG_BUILTIN

v6.0.0-96-g51489b8419

Comment 6 Yanqiu Zhang 2020-05-08 13:37:20 UTC

Verify this bug on:
libvirt-daemon-6.3.0-1.module+el8.3.0+6478+69f490bb.x86_64
qemu-kvm-4.2.0-19.module+el8.3.0+6478+69f490bb.x86_64

Steps:
1.Check capabilities:
# cat /var/cache/libvirt/qemu/capabilities/3c76bc41d59c0c7314b1ae8e63f4f765d2cf16abaeea081b3ca1f5d8732f7bb1.xml |grep rng -i
  <flag name='virtio-rng'/>
  <flag name='rng-random'/>
  <flag name='rng-egd'/>
  <flag name='rng-builtin'/>

2. Start guest
# virsh start avocado-vt-vm1
Domain avocado-vt-vm1 started

# virsh dumpxml avocado-vt-vm1 |grep 'rng m' -A4
    <rng model='virtio'>
      <backend model='builtin'/>
      <alias name='rng0'/>
      <address type='pci' domain='0x0000' bus='0x06' slot='0x00' function='0x0'/>
    </rng>

# ps aux|grep qemu-kvm|grep rng
-object rng-builtin,id=objrng0 -device virtio-rng-pci,rng=objrng0,id=rng0,bus=pci.6,addr=0x0

Check audit log:
type=EXECVE msg=audit(1588840811.351:1386):...a80="-object" a81="rng-builtin,id=objrng0" a82="-device" a83="virtio-rng-pci,rng=objrng0,id=rng0,bus=pci.6,addr=0x0"

[root@localhost ~]# cat /sys/devices/virtual/misc/hw_random/rng_available
virtio_rng.0
[root@localhost ~]# cat /sys/devices/virtual/misc/hw_random/rng_current
virtio_rng.0
[root@localhost ~]# hexdump -C /dev/hwrng -n 64
00000000  b3 a3 22 a5 c3 da ca ca  8b 0f 3d 68 45 a6 04 40  |..".......=hE..@|
00000010  e9 e9 82 58 bf d5 8c af  d5 5c 25 9d f8 b0 30 98  |...X.....\%...0.|
00000020  71 c3 02 55 68 97 f5 38  4a 99 77 cf 06 4a 60 20  |q..Uh..8J.w..J` |
00000030  f6 b9 55 b7 2e 07 8b a6  c6 4d 1e 1e 7f 0f 83 27  |..U......M.....'|
00000040

3.Check rate
<rng model='virtio'>
      <rate bytes='5000' period='2000'/>
      <backend model='builtin'/>
      <alias name='rng0'/>
      <address type='pci' domain='0x0000' bus='0x06' slot='0x00' function='0x0'/>
    </rng>

-object rng-builtin,id=objrng0 -device virtio-rng-pci,rng=objrng0,id=rng0,max-bytes=5000,period=2000,bus=pci.6,addr=0x0

[root@localhost ~]# dd if=/dev/hwrng of=/tmp/rate
39+0 records in
39+0 records out
19968 bytes (20 kB, 20 KiB) copied, 8.00539 s, 2.5 kB/s

4.Hotplug/unplug
# virsh attach-device avocado-vt-vm1 rng-builtin_alias.xml
Device attached successfully

# virsh dumpxml avocado-vt-vm1 |grep 'rng m' -A5
    <rng model='virtio'>
      <backend model='builtin'/>
      <alias name='ua-c3aee135-3a35-4296-8e60-5fbbc2cf0f35'/>
      <address type='pci' domain='0x0000' bus='0x06' slot='0x00' function='0x0'/>
    </rng>
  </devices>

[root@localhost ~]# hexdump -C /dev/hwrng -n 64
00000000  cf ef 7a b2 ca 7e f8 63  cc 81 2d 25 b6 60 49 ad  |..z..~.c..-%.`I.|
00000010  6d 55 d1 7c f5 a8 d4 6e  5e 1d 04 66 81 ad 96 da  |mU.|...n^..f....|
00000020  3b 82 d0 e7 86 b4 4b 8e  b7 b8 7c 1d 45 86 e1 61  |;.....K...|.E..a|
00000030  75 b2 bf c4 1d 2c ef d1  4e 09 0e b9 c5 ff 14 6a  |u....,..N......j|
00000040

# virsh detach-device avocado-vt-vm1 rng-builtin_alias.xml
Device detached successfully

# virsh dumpxml avocado-vt-vm1 |grep 'rng m' -A5

[root@localhost ~]# hexdump -C /dev/hwrng -n 64
hexdump: /dev/hwrng: No such device

Retest with "--persistent" option, get the same results.

5. Migration
#  virsh migrate avocado-vt-vm1 --live qemu+ssh://dell***/system --verbose
Migration: [100 %]

#  virsh migrate avocado-vt-vm1 --live qemu+ssh://dell***/system --verbose --p2p --postcopy
Migration: [100 %]

And target guest rng works well.

Comment 9 errata-xmlrpc 2020-11-17 17:46:15 UTC

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 (virt:8.3 bug fix and enhancement update), 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://access.redhat.com/errata/RHBA-2020:5137