Re: [PATCH 1/2] pcie: Don't try triggering a LSI when not defined

[Frederic Barrat]

On 24/03/2022 14:07, Daniel Henrique Barboza wrote:
> On 3/21/22 12:33, Frederic Barrat wrote:
> > This patch skips [de]asserting a LSI interrupt if the device doesn't
> > have any LSI defined. Doing so would trigger an assert in
> > pci_irq_handler().
> >
> > The PCIE root port implementation in qemu requests a LSI (INTA), but a
> > subclass may want to change that behavior since it's a valid
> > configuration. For example on the POWER8/POWER9/POWER10 systems, the
> > root bridge doesn't request any LSI.
> >
> > Signed-off-by: Frederic Barrat <fbarrat@linux.ibm.com>
> > ---
>
> I assume that it's easier to handle just the codepaths that powernv PHBs 
> uses
> rather than handling all instances where pci_irq_handler() would be 
> asserting
> without LSIs.


The real reason is that the LSI is added when we realize the 
TYPE_PCIE_ROOT_PORT object. See rp_realize(). So I'm only trying to fix 
the code paths that can be called from a subclass of TYPE_PCIE_ROOT_PORT 
which would choose to override the "interrupt pin" setting in the config 
space. I believe they are all covered by this patch.
The assert() in pci_irq_handler() is there for a reason and I don't want 
to mess with that.

  Fred


> Patch LGTM. Small nits below:
>
> >   hw/pci/pcie.c     | 8 ++++++--
> >   hw/pci/pcie_aer.c | 4 +++-
> >   2 files changed, 9 insertions(+), 3 deletions(-)
> >
> > diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
> > index 67a5d67372..71c5194b80 100644
> > --- a/hw/pci/pcie.c
> > +++ b/hw/pci/pcie.c
> > @@ -354,7 +354,9 @@ static void hotplug_event_notify(PCIDevice *dev)
> >       } else if (msi_enabled(dev)) {
> >           msi_notify(dev, pcie_cap_flags_get_vector(dev));
> >       } else {
> > -        pci_set_irq(dev, dev->exp.hpev_notified);
> > +        if (pci_intx(dev) != -1) {
> > +            pci_set_irq(dev, dev->exp.hpev_notified);
> > +        }
>
>
> Since you're not doing anything unless the condition is met, you can use 
> 'else if'
> like it's done in the other conditionals:
>
>
>      if (msix_enabled(dev)) {
>          msix_notify(dev, pcie_cap_flags_get_vector(dev));
>      } else if (msi_enabled(dev)) {
>          msi_notify(dev, pcie_cap_flags_get_vector(dev));
>      } else if (pci_intx(dev) != -1) {
>          pci_set_irq(dev, dev->exp.hpev_notified);
>      }
>
>
>
> >       }
> >   }
> > @@ -362,7 +364,9 @@ static void hotplug_event_clear(PCIDevice *dev)
> >   {
> >       hotplug_event_update_event_status(dev);
> >       if (!msix_enabled(dev) && !msi_enabled(dev) && 
> > !dev->exp.hpev_notified) {
> > -        pci_irq_deassert(dev);
> > +        if (pci_intx(dev) != -1) {
> > +            pci_irq_deassert(dev);
> > +        }
> >       }
>
> Similar comment here:
>
>      if (!msix_enabled(dev) && !msi_enabled(dev) && 
> !dev->exp.hpev_notified &&
>          pci_intx(dev) != -1) {
>          pci_irq_deassert(dev);
>      }
>
>
>
> >   }
> > diff --git a/hw/pci/pcie_aer.c b/hw/pci/pcie_aer.c
> > index e1a8a88c8c..d936bfca20 100644
> > --- a/hw/pci/pcie_aer.c
> > +++ b/hw/pci/pcie_aer.c
> > @@ -291,7 +291,9 @@ static void pcie_aer_root_notify(PCIDevice *dev)
> >       } else if (msi_enabled(dev)) {
> >           msi_notify(dev, pcie_aer_root_get_vector(dev));
> >       } else {
> > -        pci_irq_assert(dev);
> > +        if (pci_intx(dev) != -1) {
> > +            pci_irq_assert(dev);
> > +        }
>
>
> And here:
>
>      if (msix_enabled(dev)) {
>          msix_notify(dev, pcie_aer_root_get_vector(dev));
>      } else if (msi_enabled(dev)) {
>          msi_notify(dev, pcie_aer_root_get_vector(dev));
>      } else if (pci_intx(dev) != -1) {
>          pci_irq_assert(dev);
>      }
>
>
>
> Thanks,
>
>
> Daniel
>
> >       }
> >   }