Re: [PATCH v3 0/2] hw/nvme: add irqfd support

[Jinhao Fan]

at 4:14 AM, Klaus Jensen <its@irrelevant.dk> wrote:

> From: Klaus Jensen <k.jensen@samsung.com>
> 
> This is a re-spin of Jinhao's irqfd support series that fixes msix
> vector masking/unmasking to work correctly.
> 
> I kept being bugged out about that msi route not getting updated, so I
> hit the code into submission with a hammer.
> 
> I finally noticed the core issue:
> 
>  1. The vector notifiers was never set because msix is not enabled at
>     the point where nvme_init_pci() is called.
> 
>     Move this call to nvme_start_ctrl().
> 
> Since the unmask callback was suddenly getting called now, another fix
> was needed:
> 
>  2. Call kvm_irqchip_add_irqfd_notifier_gsi() in the unmask handler -
>     not in nvme_init_irq_notifier(). The vectors may potentially be
>     masked/unmasked and shall cause a pair of add_irqfd and
>     remove_irqfd calls. Removing it from nvme_init_irq_notifier() makes
>     sure we do not try to double add.
> 
> Now it does what it is supposed to; no hacks required :)
> 
> Jinhao Fan (2):
>  hw/nvme: support irq(de)assertion with eventfd
>  hw/nvme: use KVM irqfd when available
> 
> hw/nvme/ctrl.c       | 261 ++++++++++++++++++++++++++++++++++++++++---
> hw/nvme/nvme.h       |   6 +
> hw/nvme/trace-events |   3 +
> 3 files changed, 253 insertions(+), 17 deletions(-)
> 
> -- 
> 2.37.2

This patch series works well on my machine without a vIOMMU. 

Just to confirm my understanding, the workflow of updating msi route is:
Host driver update MSI msg and addr -> unmask callback get called ->
kvm_irqchip_update_msi_route() does the work. Right?