Messages in this thread Patch in this message | | | Date | Mon, 17 Jan 2022 09:14:13 +0000 | From | Marc Zyngier <> | Subject | Re: PCI MSI issue for maxcpus=1 |
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On Sun, 16 Jan 2022 12:07:59 +0000, Marc Zyngier <maz@kernel.org> wrote: > > On Fri, 07 Jan 2022 11:24:38 +0000, > John Garry <john.garry@huawei.com> wrote: > > > > Hi Marc, > > > > >> So it's the driver call to pci_alloc_irq_vectors_affinity() which > > >> errors [1]: > > >> > > >> [ 9.619070] hisi_sas_v3_hw: probe of 0000:74:02.0 failed with error -2 > > > Can you log what error is returned from pci_alloc_irq_vectors_affinity()? > > > > -EINVAL > > > > > > > >> Some details: > > >> - device supports 32 MSI > > >> - min and max msi for that function is 17 and 32, respect. > > > This 17 is a bit odd, owing to the fact that MultiMSI can only deal > > > with powers of 2. You will always allocate 32 in this case. Not sure > > > why that'd cause an issue though. Unless... > > > > Even though 17 is the min, we still try for nvec=32 in > > msi_capability_init() as possible CPUs is 96. > > > > > > > >> - affd pre and post are 16 and 0, respect. > > >> > > >> I haven't checked to see what the issue is yet and I think that the > > >> pci_alloc_irq_vectors_affinity() usage is ok... > > > ... we really end-up with desc->nvec_used == 32 and try to activate > > > past vector 17 (which is likely to fail). Could you please check this? > > > > Yeah, that looks to fail. Reason being that in the GIC ITS driver when > > we try to activate the irq for this managed interrupt all cpus in the > > affinity mask are offline. Calling its_irq_domain_activate() -> > > its_select_cpu() it gives cpu=nr_cpu_ids. The affinity mask for that > > interrupt is 24-29. > > I guess that for managed interrupts, it shouldn't matter, as these > interrupts should only be used when the relevant CPUs come online. > > Would something like below help? Totally untested, as I don't have a > Multi-MSI capable device that I can plug in a GICv3 system (maybe I > should teach that to a virtio device...).
Actually, if the CPU online status doesn't matter for managed affinity interrupts, then the correct fix is this:
diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c index d25b7a864bbb..af4e72a6be63 100644 --- a/drivers/irqchip/irq-gic-v3-its.c +++ b/drivers/irqchip/irq-gic-v3-its.c @@ -1624,7 +1624,7 @@ static int its_select_cpu(struct irq_data *d, cpu = cpumask_pick_least_loaded(d, tmpmask); } else { - cpumask_and(tmpmask, irq_data_get_affinity_mask(d), cpu_online_mask); + cpumask_copy(tmpmask, irq_data_get_affinity_mask(d)); /* If we cannot cross sockets, limit the search to that node */ if ((its_dev->its->flags & ITS_FLAGS_WORKAROUND_CAVIUM_23144) && Thanks,
M.
-- Without deviation from the norm, progress is not possible.
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