On Tue, Nov 24 2020 at 21:03, Laurent Vivier wrote:
> With virtio multiqueue, normally each queue IRQ is mapped to a CPU.
>
> This problem cannot be shown on x86_64 for two reasons:
There is only _ONE_ reason why this is not a problem on x86. x86 uses
the generic PCI/MSI domain which supports this out of the box.
> - 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()
This is a problem on _all_ variants of PPC MSI providers, not only for
pseries. It's not restricted to virtscsi devices either, that's just the
device which made you discover this.
Thanks,
tglx
