Re: [PATCH v2 2/3] hw/nvme: use KVM irqfd when available

[Klaus Jensen <its@irrelevant.dk>]

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On Aug 26 09:34, Keith Busch wrote:
> On Fri, Aug 26, 2022 at 11:12:04PM +0800, Jinhao Fan wrote:
> > Use KVM's irqfd to send interrupts when possible. This approach is
> > thread safe. Moreover, it does not have the inter-thread communication
> > overhead of plain event notifiers since handler callback are called
> > in the same system call as irqfd write.
> > 
> > Signed-off-by: Jinhao Fan <fanjinhao21s@ict.ac.cn>
> > Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
> 
> No idea what's going on here... This one is causing the following assert
> failure with --enable-kvm:
> 
>   qemu-system-x86_64: ../accel/kvm/kvm-all.c:1781: kvm_irqchip_commit_routes: Assertion `ret == 0' failed.
> 
> I find it calls KVM_SET_GSI_ROUTING ioctl with gsi set to KVM_IRQ_ROUTING_MSI,
> and linux kernel returns EINVAL in that case. It's never set that way without
> this patch. Am I the only one seeing this?

Argh, sorry, I threw that patch together a bit too quickly. I was just
so pumped because I believed I had solved the issue hehe.

Are you missing the ioeventfd=on and irq-eventfd=on parameters by any
chance? Without those I'm also getting an assertion, but a different one

qemu-system-x86_64: ../hw/pci/msix.c:119: msix_fire_vector_notifier: Assertion `ret >= 0' failed.



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