Note: This bug is displayed in read-only format because the product is no longer active in Red Hat Bugzilla.

RHEL Engineering is moving the tracking of its product development work on RHEL 6 through RHEL 9 to Red Hat Jira (issues.redhat.com). If you're a Red Hat customer, please continue to file support cases via the Red Hat customer portal. If you're not, please head to the "RHEL project" in Red Hat Jira and file new tickets here. Individual Bugzilla bugs in the statuses "NEW", "ASSIGNED", and "POST" are being migrated throughout September 2023. Bugs of Red Hat partners with an assigned Engineering Partner Manager (EPM) are migrated in late September as per pre-agreed dates. Bugs against components "kernel", "kernel-rt", and "kpatch" are only migrated if still in "NEW" or "ASSIGNED". If you cannot log in to RH Jira, please consult article #7032570. That failing, please send an e-mail to the RH Jira admins at rh-issues@redhat.com to troubleshoot your issue as a user management inquiry. The email creates a ServiceNow ticket with Red Hat. Individual Bugzilla bugs that are migrated will be moved to status "CLOSED", resolution "MIGRATED", and set with "MigratedToJIRA" in "Keywords". The link to the successor Jira issue will be found under "Links", have a little "two-footprint" icon next to it, and direct you to the "RHEL project" in Red Hat Jira (issue links are of type "https://issues.redhat.com/browse/RHEL-XXXX", where "X" is a digit). This same link will be available in a blue banner at the top of the page informing you that that bug has been migrated.

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:
Embargoed:

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