On Wed, Feb 09, 2022 at 10:12:20AM -0600, Bjorn Helgaas wrote:
> On Wed, Feb 09, 2022 at 10:37:20AM +0800, Boqun Feng wrote:
> > On ARM64 Hyper-V guests, SPIs are used for the interrupts of virtual PCI
> > devices, and SPIs can be managed directly via GICD registers. Therefore
> > the retarget interrupt hypercall is not needed on ARM64.
> >
> > The retarget interrupt hypercall related code is now put in a helper
> > function and only called on x86.
> >
> > Signed-off-by: Boqun Feng <boqun.feng@xxxxxxxxx>
> > ---
> > drivers/pci/controller/pci-hyperv.c | 11 +++++++++--
> > 1 file changed, 9 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
> > index 20ea2ee330b8..80aa33ef5bf0 100644
> > --- a/drivers/pci/controller/pci-hyperv.c
> > +++ b/drivers/pci/controller/pci-hyperv.c
> > @@ -1457,7 +1457,7 @@ static void hv_irq_mask(struct irq_data *data)
> > }
> >
> > /**
> > - * hv_irq_unmask() - "Unmask" the IRQ by setting its current
> > + * __hv_irq_unmask() - "Unmask" the IRQ by setting its current
> > * affinity.
> > * @data: Describes the IRQ
> > *
> > @@ -1466,7 +1466,7 @@ static void hv_irq_mask(struct irq_data *data)
> > * is built out of this PCI bus's instance GUID and the function
> > * number of the device.
> > */
> > -static void hv_irq_unmask(struct irq_data *data)
> > +static void __hv_irq_unmask(struct irq_data *data)
> > {
> > struct msi_desc *msi_desc = irq_data_get_msi_desc(data);
> > struct hv_retarget_device_interrupt *params;
> > @@ -1569,6 +1569,13 @@ static void hv_irq_unmask(struct irq_data *data)
> > if (!hv_result_success(res) && hbus->state != hv_pcibus_removing)
> > dev_err(&hbus->hdev->device,
> > "%s() failed: %#llx", __func__, res);
> > +}
> > +
> > +static void hv_irq_unmask(struct irq_data *data)
> > +{
> > + /* Only use a hypercall on x86 */
>
> This comment isn't useful because it only repeats what we can already
> see from the "IS_ENABLED(CONFIG_X86)" below and it doesn't say
> anything about *why*.
>
> Didn't we just go though an exercise of adding interfaces for
> arch-specific things, i.e., 831c1ae725f7 ("PCI: hv: Make the code arch
> neutral by adding arch specific interfaces")? Maybe this should be
> another such interface?
>
> If you add Hyper-V support for a third arch, this #ifdef will likely
> be silently incorrect. If you add an interface, there's at least a
> clue that this needs to be evaluated.
>
You are right. I will make __hv_irq_unmask() as an arch-specific
interface in the next version (probably with a better name). Thank you!
Regards,
Boqun
> > + if (IS_ENABLED(CONFIG_X86))
> > + __hv_irq_unmask(data);
> >
> > if (data->parent_data->chip->irq_unmask)
> > irq_chip_unmask_parent(data);
> > --
> > 2.35.1
> >
