Re: [PATCH 1/2] KVM: not register a IRQ bypass producer if unsupported or disabled

From
Zhenzhong Duan <hidden>
Date
2020-10-20 10:05:32
Also in
kvm, lkml
Reply to
Jason Wang, 2020-10-20
On Tue, Oct 20, 2020 at 2:23 PM Jason Wang [off-list ref] wrote:

On 2020/10/19 下午5:06, Zhenzhong Duan wrote:
quoted
If Post interrupt is disabled due to hardware limit or forcely disabled
by "intremap=nopost" parameter, return -EINVAL so that the legacy mode IRQ
isn't registered as IRQ bypass producer.

Is there any side effect if it was still registered?
Not much side effect in theory, just some legacy mode IRQs in producer
list and it's not easy to distinguish them with PI interrupt mode IRQ.
The main purpose of this patch is to provide a way for people to know
if a device IRQ is really offloaded from kernel by a print.
quoted
With this change, below message is printed:
"vfio-pci 0000:db:00.0: irq bypass producer (token 0000000060c8cda5) registration fails: -22"

I may miss something, but the patch only touches vhost-vDPA instead of VFIO?
VFIO already has above print in vfio_msi_set_vector_signal() but vhost-vDPA not.

Regards
Zhenzhong
Thread (6 messages) 6 messages, 2 authors, last reply 2020-10-20
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