From: Laurent Vivier <lvivier@redhat.com>
To: Denis Kirjanov <kda@linux-powerpc.org>
Cc: linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org,
Christoph Hellwig <hch@lst.de>, Paul Mackerras <paulus@samba.org>,
Greg Kurz <groug@kaod.org>,
linuxppc-dev@lists.ozlabs.org,
Thomas Gleixner <tglx@linutronix.de>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Michael Ellerman <mpe@ellerman.id.au>,
linux-block@vger.kernel.org,
"Michael S . Tsirkin" <mst@redhat.com>,
Marc Zyngier <maz@kernel.org>
Subject: Re: [PATCH v3 2/2] powerpc/pseries: pass MSI affinity to irq_create_mapping()
Date: Wed, 25 Nov 2020 17:24:45 +0100 [thread overview]
Message-ID: <7184880b-0351-ae18-d2e1-fab7b79fc864@redhat.com> (raw)
In-Reply-To: <CAOJe8K1Q7sGf67bdj-2Mthkj4XNR4fOSskV1dyh62AdzefhpAQ@mail.gmail.com>
On 25/11/2020 17:05, Denis Kirjanov wrote:
> On 11/25/20, Laurent Vivier <lvivier@redhat.com> wrote:
>> With virtio multiqueue, normally each queue IRQ is mapped to a CPU.
>>
>> But since commit 0d9f0a52c8b9f ("virtio_scsi: use virtio IRQ affinity")
>> this is broken on pseries.
>
> Please add "Fixes" tag.
In fact, the code in commit 0d9f0a52c8b9f is correct.
The problem is with MSI/X irq affinity and pseries. So this patch fixes more than
virtio_scsi. I put this information because this commit allows to clearly show the
problem. Perhaps I should remove this line in fact?
Thanks,
Laurent
>
> Thanks!
>
>>
>> The affinity is correctly computed in msi_desc but this is not applied
>> to the system IRQs.
>>
>> It appears the affinity is correctly passed to rtas_setup_msi_irqs() but
>> lost at this point and never passed to irq_domain_alloc_descs()
>> (see commit 06ee6d571f0e ("genirq: Add affinity hint to irq allocation"))
>> because irq_create_mapping() doesn't take an affinity parameter.
>>
>> As the previous patch has added the affinity parameter to
>> irq_create_mapping() we can forward the affinity from rtas_setup_msi_irqs()
>> to irq_domain_alloc_descs().
>>
>> With this change, the virtqueues are correctly dispatched between the CPUs
>> on pseries.
>>
>> BugId: https://bugzilla.redhat.com/show_bug.cgi?id=1702939
>> Signed-off-by: Laurent Vivier <lvivier@redhat.com>
>> Reviewed-by: Greg Kurz <groug@kaod.org>
>> ---
>> arch/powerpc/platforms/pseries/msi.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/powerpc/platforms/pseries/msi.c
>> b/arch/powerpc/platforms/pseries/msi.c
>> index 133f6adcb39c..b3ac2455faad 100644
>> --- a/arch/powerpc/platforms/pseries/msi.c
>> +++ b/arch/powerpc/platforms/pseries/msi.c
>> @@ -458,7 +458,8 @@ static int rtas_setup_msi_irqs(struct pci_dev *pdev, int
>> nvec_in, int type)
>> return hwirq;
>> }
>>
>> - virq = irq_create_mapping(NULL, hwirq);
>> + virq = irq_create_mapping_affinity(NULL, hwirq,
>> + entry->affinity);
>>
>> if (!virq) {
>> pr_debug("rtas_msi: Failed mapping hwirq %d\n", hwirq);
>> --
>> 2.28.0
>>
>>
>
next prev parent reply other threads:[~2020-11-25 16:25 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-25 15:09 [PATCH v3 0/2] powerpc/pseries: fix MSI/X IRQ affinity on pseries Laurent Vivier
2020-11-25 15:09 ` [PATCH v3 1/2] genirq/irqdomain: Add an irq_create_mapping_affinity() function Laurent Vivier
2020-11-25 15:09 ` [PATCH v3 2/2] powerpc/pseries: pass MSI affinity to irq_create_mapping() Laurent Vivier
2020-11-25 16:05 ` Denis Kirjanov
2020-11-25 16:24 ` Laurent Vivier [this message]
2020-11-25 16:42 ` Marc Zyngier
2020-11-25 17:34 ` Greg Kurz
2020-11-26 3:22 ` Michael Ellerman
2020-11-26 3:22 ` Michael Ellerman
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