lkml.org 
[lkml]   [2020]   [Nov]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 2/2] powerpc/pseries: pass MSI affinity to irq_create_mapping()
Date
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.

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.

This problem cannot be shown on x86_64 for two reasons:

- the call path traverses arch_setup_msi_irqs() that is arch specific:

virtscsi_probe()
virtscsi_init()
vp_modern_find_vqs()
vp_find_vqs()
vp_find_vqs_msix()
pci_alloc_irq_vectors_affinity()
__pci_enable_msix_range()
pci_msi_setup_msi_irqs()
arch_setup_msi_irqs()
rtas_setup_msi_irqs()
irq_create_mapping()
irq_domain_alloc_descs()
__irq_alloc_descs()

- and x86_64 has CONFIG_PCI_MSI_IRQ_DOMAIN that uses another path:

virtscsi_probe()
virtscsi_init()
vp_modern_find_vqs()
vp_find_vqs()
vp_find_vqs_msix()
pci_alloc_irq_vectors_affinity()
__pci_enable_msix_range()
__msi_domain_alloc_irqs()
__irq_domain_alloc_irqs()
__irq_alloc_descs()

Signed-off-by: Laurent Vivier <lvivier@redhat.com>
---
arch/powerpc/platforms/pseries/msi.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/pseries/msi.c b/arch/powerpc/platforms/pseries/msi.c
index 42ba08eaea91..58197f92c6a2 100644
--- a/arch/powerpc/platforms/pseries/msi.c
+++ b/arch/powerpc/platforms/pseries/msi.c
@@ -458,7 +458,7 @@ static int rtas_setup_msi_irqs(struct pci_dev *pdev, int nvec_in, int type)
return hwirq;
}

- virq = irq_create_mapping(NULL, hwirq, NULL);
+ virq = irq_create_mapping(NULL, hwirq, entry->affinity);

if (!virq) {
pr_debug("rtas_msi: Failed mapping hwirq %d\n", hwirq);
--
2.28.0
\
 
 \ /
  Last update: 2020-11-24 21:06    [W:0.116 / U:0.784 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site