2023-12-06 20:44:22

by Thomas Gleixner

Subject: Re: [PATCH RFC 11/13] iommu/vt-d: Add an irq_chip for posted MSIs

On Sat, Nov 11 2023 at 20:16, Jacob Pan wrote:
> static void fill_msi_msg(struct msi_msg *msg, u32 index, u32 subhandle)
> {
> memset(msg, 0, sizeof(*msg));
> @@ -1361,7 +1397,7 @@ static int intel_irq_remapping_alloc(struct irq_domain *domain,
>
> irq_data->hwirq = (index << 16) + i;
> irq_data->chip_data = ird;
> - irq_data->chip = &intel_ir_chip;
> + irq_data->chip = posted_msi_supported() ? &intel_ir_chip_post_msi : &intel_ir_chip;

This is just wrong because you change the chip to posted for _ALL_
domains unconditionally.

The only domains which want this chip are the PCI/MSI domains. And those
are distinct from the domains which serve IO/APIC, HPET, no?

So you can set that chip only for PCI/MSI and just let IO/APIC, HPET
domains keep the original chip, which spares any modification of the
IO/APIC domain.

2023-12-13 03:44:36

by Jacob Pan

Subject: Re: [PATCH RFC 11/13] iommu/vt-d: Add an irq_chip for posted MSIs

Hi Thomas,

On Wed, 06 Dec 2023 21:44:02 +0100, Thomas Gleixner <[email protected]>
wrote:

> On Sat, Nov 11 2023 at 20:16, Jacob Pan wrote:
> > static void fill_msi_msg(struct msi_msg *msg, u32 index, u32 subhandle)
> > {
> > memset(msg, 0, sizeof(*msg));
> > @@ -1361,7 +1397,7 @@ static int intel_irq_remapping_alloc(struct
> > irq_domain *domain,
> > irq_data->hwirq = (index << 16) + i;
> > irq_data->chip_data = ird;
> > - irq_data->chip = &intel_ir_chip;
> > + irq_data->chip = posted_msi_supported() ?
> > &intel_ir_chip_post_msi : &intel_ir_chip;
>
> This is just wrong because you change the chip to posted for _ALL_
> domains unconditionally.
>
> The only domains which want this chip are the PCI/MSI domains. And those
> are distinct from the domains which serve IO/APIC, HPET, no?
>
> So you can set that chip only for PCI/MSI and just let IO/APIC, HPET
> domains keep the original chip, which spares any modification of the
> IO/APIC domain.
>
>
make sense.
- irq_data->chip = posted_msi_supported() ? &intel_ir_chip_post_msi : &intel_ir_chip;
+ if ((info->type == X86_IRQ_ALLOC_TYPE_PCI_MSI) && posted_msi_supported())
+ irq_data->chip = &intel_ir_chip_post_msi;
+ else
+ irq_data->chip = &intel_ir_chip;

Now in IRQ debugfs, I can see the correct IR chips for IOAPIC IRQs and
MSIs.

e.g


domain: IO-APIC-8
hwirq: 0x9
chip: IR-IO-APIC
flags: 0x410
IRQCHIP_SKIP_SET_WAKE
parent:
domain: INTEL-IR-9-13
hwirq: 0x80000
chip: INTEL-IR
flags: 0x0
parent:
domain: VECTOR


domain: IR-PCI-MSI-0000:3d:00.4-11
hwirq: 0x0
chip: IR-PCI-MSI-0000:3d:00.4
flags: 0x430
IRQCHIP_SKIP_SET_WAKE
IRQCHIP_ONESHOT_SAFE
parent:
domain: INTEL-IR-4-13
hwirq: 0x0
chip: INTEL-IR-POST
flags: 0x0
parent:
domain: VECTOR


Thanks,

Jacob