Re: [report] boot a vm that with PCI only hierarchy devices and with GICv3 , it's failed.

[Marc Zyngier <marc.zyngier@arm.com>]

On 18/07/17 05:07, wanghaibin wrote:
> Hi, all:
> 
> I met a problem, I just try to test PCI only hierarchy devices model (qemu/docs/pcie.txt  sections 2.3)
> 
> Here is part of qemu cmd:
> -device i82801b11-bridge,id=pci.1,bus=pcie.0,addr=0x1 -device pci-bridge,chassis_nr=2,id=pci.2,bus=pci.1,addr=0x0 -device usb-ehci,id=usb,bus=pci.2,addr=0x2
> -device virtio-scsi-pci,id=scsi0,bus=pci.2,addr=0x3 -netdev tap,fd=27,id=hostnet0,vhost=on,vhostfd=28 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:60:6b:1d,bus=pci.2,addr=0x1
> -vnc 0.0.0.0:0 -device virtio-gpu-pci,id=video0,bus=pci.2,addr=0x4
> 
> A single DMI-PCI Bridge, a single PCI-PCI Bridge attached to it.  Four PCI_DEV legacy devices (usb, virtio-scsi-pci, virtio-gpu-pci, virtio-net-pci)attached to the PCI-PCI Bridge.
> Boot the vm, it's failed.
> 
> I try to debug this problem, and the info just as follow:
> (1) Since Eric Auger commit (0d44cdb631ef53ea75be056886cf0541311e48df: KVM: arm64: vgic-its: Interpret MAPD Size field and check related errors), This problem has been exposed.
>     Of course, I think this commit must be correct surely.
> 
> (2) For guestOS, I notice Marc commit (e8137f4f5088d763ced1db82d3974336b76e1bd2: irqchip: gicv3-its: Iterate over PCI aliases to generate ITS configuration).  This commit brings in that the
>     four PCI_DEV legacy devices shared the same devID, same its_dev, same ITT tables, but I think here calculate with wrong total msi vector count.
>     (Currently, It seems the total count is the vector count of virtio-net-pci + PCI-PCI bridge + dmi-pci bridge, maybe here should be the total count of the four PCI_DEV legacy devices vector count),
>     So that, any pci device using the over bounds eventID and mapti at a certain moment , the abnormal behavior will captured by Eric's commit.
> 
> Actually, I don't understand very well about non-transparent bridge, PCI aliases. So just supply these message.

+Robin, who is the author of that patch.

Regarding (2), the number of MSIs should be the total number of devices
that are going to generate the same DevID. Since the bridge is
non-transparent, everything behind it aliases with it. So you should
probably see all the virtio devices and the bridges themselves being
counted. If that's not the case, then "we have a bug"(tm).

Can you please post your full qemu cmd line so that we can reproduce it
and investigate the issue?

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...