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Re: [PATCH v2 1/3] hw/nvme: support irq(de)assertion with eventfd
From: |
Klaus Jensen |
Subject: |
Re: [PATCH v2 1/3] hw/nvme: support irq(de)assertion with eventfd |
Date: |
Thu, 25 Aug 2022 13:56:37 +0200 |
On Aug 25 19:16, Jinhao Fan wrote:
> On 8/25/2022 5:33 PM, Klaus Jensen wrote:
> > I'm still a bit perplexed by this issue, so I just tried moving
> > nvme_init_irq_notifier() to the end of nvme_init_cq() and removing this
> > first_io_cqe thing. I did not observe any particular issues?
> >
> > What bad behavior did you encounter, it seems to work fine to me
>
> The kernel boots up and got stuck, waiting for interrupts. Then the request
> times out and got retried three times. Finally the driver seems to decide
> that the drive is down and continues to boot.
>
> I added some prints during debugging and found that the MSI-X message which
> got registered in KVM via kvm_irqchip_add_msi_route() is not the same as the
> one actually used in msix_notify().
>
> Are you sure you are using KVM's irqfd?
>
Pretty sure? Using "ioeventfd=on,irq-eventfd=on" on the controller.
And the following patch.
diff --git i/hw/nvme/ctrl.c w/hw/nvme/ctrl.c
index 30bbda7bb5ae..b2e41d3bd745 100644
--- i/hw/nvme/ctrl.c
+++ w/hw/nvme/ctrl.c
@@ -1490,21 +1490,6 @@ static void nvme_post_cqes(void *opaque)
if (!pending) {
n->cq_pending++;
}
-
- if (unlikely(cq->first_io_cqe)) {
- /*
- * Initilize event notifier when first cqe is posted. For
irqfd
- * support we need to register the MSI message in KVM. We
- * can not do this registration at CQ creation time because
- * Linux's NVMe driver changes the MSI message after CQ
creation.
- */
- cq->first_io_cqe = false;
-
- if (n->params.irq_eventfd) {
- nvme_init_irq_notifier(n, cq);
- }
- }
-
}
nvme_irq_assert(n, cq);
@@ -4914,11 +4899,14 @@ static void nvme_init_cq(NvmeCQueue *cq, NvmeCtrl *n,
uint64_t dma_addr,
}
n->cq[cqid] = cq;
cq->timer = timer_new_ns(QEMU_CLOCK_VIRTUAL, nvme_post_cqes, cq);
+
/*
* Only enable irqfd for IO queues since we always emulate admin queue
* in main loop thread
*/
- cq->first_io_cqe = cqid != 0;
+ if (cqid && n->params.irq_eventfd) {
+ nvme_init_irq_notifier(n, cq);
+ }
}
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