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

[Daniel Henrique Barboza]

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 <fbar...@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.


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

      }
  }