Bug 1460957

Summary: Implement INTx to GSI routing on ARM virt
Product: Red Hat Enterprise Linux 7 Reporter: Eric Auger <eric.auger>
Component: qemu-kvm-maAssignee: Eric Auger <eric.auger>
Status: CLOSED ERRATA QA Contact: Virtualization Bugs <virt-bugs>
Severity: medium Docs Contact:
Priority: medium    
Version: 7.4-AltCC: alex.williamson, chayang, drjones, eric.auger, hhuang, jfeeney, juzhang, knoel, michen, mrezanin, rbalakri, virt-maint, wei
Target Milestone: rcKeywords: OtherQA
Target Release: ---   
Hardware: aarch64   
OS: Linux   
Whiteboard:
Fixed In Version: qemu-kvm-ma-2.10.0-5.el7 Doc Type: If docs needed, set a value
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Story Points: ---
Clone Of: Environment:
Last Closed: 2018-04-10 14:50:48 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:
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Bug Depends On:    
Bug Blocks: 1173755    

Description Eric Auger 2017-06-13 08:55:37 UTC 
ARM virt uses GPEX PCIe bridge. This latter does not implement INTx to GSI routing. PCIe/INTx assignment works but the consequence is irqfd is not used with INTx interrupts and VFIO handlers are executed on userspace leading to an important performance degradation.

This is witnessed by the following message;

qemu-system-aarch64: -device vfio-pci,host=0006:90:00.0: PCI: Bug - unimplemented PCI INTx routing (gpex-pcihost)
qemu-system-aarch64: PCI: Bug - unimplemented PCI INTx routing (gpex-pcihost)
qemu-system-aarch64: PCI: Bug - unimplemented PCI INTx routing (gpex-pcihost)

2 patches were submitted a while ago on the ML but have never been upstreamed (https://patchwork.kernel.org/patch/8165031/).

- Generic PCIe host bridge INTx determination for INTx routing
- Add a function to determine interrupt number for INTx routing

This is time to respin & complete the work.
Comment 2 Eric Auger 2017-06-14 13:59:12 UTC 
Better to make it for rhel-7.4 if it is possible.
Comment 10 Miroslav Rezanina 2017-11-08 17:57:50 UTC 
Fix included in qemu-kvm-ma-2.10.0-5.el7
Comment 17 errata-xmlrpc 2018-04-10 14:50:48 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://access.redhat.com/errata/RHBA-2018:0831