Re: [PATCH 0/4] hw/nvme: add irqfd support

[Klaus Jensen <its@irrelevant.dk>]

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On Aug 11 23:37, Jinhao Fan wrote:
> This patch series changes qemu-nvme's interrupt emulation to use event
> notifiers, which can ensure thread-safe interrupt delivery when iothread
> is used. In the first two patches, I convert qemu-nvme's IO emulation
> logic to send irq via eventfd, so that the actual assertion and
> deassertion is always done in the main loop thread with BQL held. In the
> third patch, support is added to send irq via KVM irqfd, bypassing
> qemu's MSI-x emulation. In the last patch, I add MSI-x mask handlers
> when irqfd is enabled so that qemu-nvme knows which vector is masked
> even when qemu's MSI-x emulation is bypassed.
> 
> Jinhao Fan (4):
>   hw/nvme: avoid unnecessary call to irq (de)assertion functions
>   hw/nvme: add option to (de)assert irq with eventfd
>   hw/nvme: use irqfd to send interrupts
>   hw/nvme: add MSI-x mask handlers for irqfd
> 
>  hw/nvme/ctrl.c       | 251 +++++++++++++++++++++++++++++++++++++++----
>  hw/nvme/nvme.h       |   7 ++
>  hw/nvme/trace-events |   3 +
>  3 files changed, 243 insertions(+), 18 deletions(-)
> 
> -- 
> 2.25.1
> 

Hi Jinhao,

This series all looks pretty good to me. And, incidentally, it is also
super cool work :)

It can use a bit of clean up (the code duplication mentioned previously
by both Stefan and me) - but all the logic seems sound to me and my
testing is happy. Following up on my suggestion to drop the MSI-X
mask/unmasking, I gave the logic a thorough look it looks sound to me.
I'm gonna see what I can come up with for qtest. I suggest you just keep
going on iothread support.

Please post a v2 (all 4 patches) with suggested cleanups and we take it
from there.

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