Bug 1261846

Summary:	qemu-kvm-rhev: 64-bit PCI bars may overlap hotplugged memory and vice verse
Product:	Red Hat Enterprise Linux 7	Reporter:	Igor Mammedov <imammedo>
Component:	qemu-kvm-rhev	Assignee:	Igor Mammedov <imammedo>
Status:	CLOSED ERRATA	QA Contact:	Virtualization Bugs <virt-bugs>
Severity:	high	Docs Contact:
Priority:	medium
Version:	7.2	CC:	hhuang, huding, juzhang, pezhang, qiguo, tlavigne, virt-maint, xfu
Target Milestone:	rc
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:	qemu-kvm-rhev-2.3.0-23.el7	Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2015-12-04 16:56:52 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:

Description Igor Mammedov 2015-09-10 10:02:36 UTC

Description of problem:
In QEMU reserved-memory-end tells firmware address from which
it could start treating memory as PCI address space
and map PCI BARs after it to avoid collisions with
RAM.
Currently it is incorrectly pointing to address where
hotplugged memory range starts which could redirect
hotplugged RAM accesses to PCI BARs when firmware
maps them over RAM or vice verse.
Fix this by pointing reserved-memory-end to the end
of memory hotplug area.

Version-Release number of selected component (if applicable):
qemu-kvm-1.5.3-102

Comment 4 Igor Mammedov 2015-09-11 12:49:54 UTC

Easy way to verify bug,

1: 
/usr/libexec/qemu-kvm  -m 4G,slots=1,maxmem=12G \
   -object memory-backend-ram,id=dimm1,size=1G \
   -device ivshmem,size=1G,shm=ssss \
   -device pc-dimm,id=d1,memdev=dimm1 \
   -monitor stdio -M pc-i440fx-rhel7.2.0

2:
execute in monitor prompt command 'info mtree'

Actual results:
  0000000140000000-000000017fffffff (prio 0, RW): ivshmem.bar2
...
0000000140000000-000000037fffffff (prio 0, RW): hotplug-memory
  0000000140000000-000000017fffffff (prio 0, RW): dimm1

Expected results:
ivshmem.bar2 shouldn't intersect with hotplugged memory
and should start beyond hotplug-memory region range, i.e. after 000000037fffffff

with -M pc-i440fx-rhel7.1.0 Expected result should stay broken like in Actual result.

Comment 5 Igor Mammedov 2015-09-11 13:27:16 UTC

http://post-office.corp.redhat.com/archives/rhvirt-patches/2015-September/msg00211.html

Comment 6 Miroslav Rezanina 2015-09-15 10:51:15 UTC

Fix included in qemu-kvm-rhev-2.3.0-23.el7

Comment 7 Pei Zhang 2015-09-16 05:24:57 UTC

Summary: The results of verification can prove that this bug has been fixed.


Reproduced:
Host:
kernel:3.10.0-316.el7.x86_64
qemu-img-rhev-2.3.0-22.el7.x86_64

Steps:
1.# /usr/libexec/qemu-kvm  -m 4G,slots=1,maxmem=12G \
   -object memory-backend-ram,id=dimm1,size=1G \
   -device ivshmem,size=1G,shm=ssss \
   -device pc-dimm,id=d1,memdev=dimm1 \
   -monitor stdio -M pc-i440fx-rhel7.2.0
(qemu)info mtree
...
      0000000140000000-000000017fffffff (prio 0, RW): ivshmem.bar2
...
  0000000140000000-000000037fffffff (prio 0, RW): hotplug-memory
    0000000140000000-000000017fffffff (prio 0, RW): dimm1

ivshmem.bar2 intersect with hotplug-memory. So this bug is reproduced.



Verified:
Host:
kernel:3.10.0-316.el7.x86_64
qemu-img-rhev-2.3.0-23.el7.x86_64

Scenario 1: -M pc-i440fx-rhel7.2.0
#/usr/libexec/qemu-kvm  -m 4G,slots=1,maxmem=12G \
   -object memory-backend-ram,id=dimm1,size=1G \
   -device ivshmem,size=1G,shm=ssss \
   -device pc-dimm,id=d1,memdev=dimm1 \
   -monitor stdio -M pc-i440fx-rhel7.2.0
(qemu)info mtree
...
    0000000380000000-00000003bfffffff (prio 0, RW): ivshmem.bar2
...
  0000000140000000-000000037fffffff (prio 0, RW): hotplug-memory
    0000000140000000-000000017fffffff (prio 0, RW): dimm1

ivshmem.bar2 doesn't intersect with hotplug-memory and start beyong hotplug-memory.　


Scenario 2: -M pc-i440fx-rhel7.1.0
#/usr/libexec/qemu-kvm  -m 4G,slots=1,maxmem=12G \
   -object memory-backend-ram,id=dimm1,size=1G \
   -device ivshmem,size=1G,shm=ssss \
   -device pc-dimm,id=d1,memdev=dimm1 \
   -monitor stdio -M pc-i440fx-rhel7.1.0
(qemu)info mtree
...
      0000000140000000-000000017fffffff (prio 0, RW): ivshmem.bar2
...
  0000000140000000-000000033fffffff (prio 0, RW): hotplug-memory
    0000000140000000-000000017fffffff (prio 0, RW): dimm1

ivshmem.bar2 intersect with hotplug-memory, it is broken.

According to Comment 4, results of Scenario 1 and Scenario 2 is expected. So this bug has been fixed.

Comment 8 juzhang 2015-09-21 03:05:07 UTC

According to comment4 and comment5, set this issue as verified.

Comment 10 errata-xmlrpc 2015-12-04 16:56:52 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, 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/RHBA-2015-2546.html