[PATCH] PCI/MSI: Check MSI_FLAG_PCI_MSI_MASK_PARENT in cond_[startup|shutdown]_parent()

[Inochi Amaoto <inochiama@gmail.com>]

For msi controller that only supports MSI_FLAG_PCI_MSI_MASK_PARENT,
the newly added callback irq_startup() and irq_shutdown() for
pci_msi[x]_tamplete will not unmask/mask the interrupt when startup/
shutdown the interrupt. This will prevent the interrupt from being
enabled/disabled normally.

Add the missing check for MSI_FLAG_PCI_MSI_MASK_PARENT in the
cond_[startup|shutdown]_parent(). So the interrupt can be normally
unmasked/masked if it does not support MSI_FLAG_PCI_MSI_MASK_PARENT.

Fixes: 54f45a30c0d0 ("PCI/MSI: Add startup/shutdown for per device domains")
Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
Closes: https://lore.kernel.org/regressions/aK4O7Hl8NCVEMznB@monster/
Reported-by: Nathan Chancellor <nathan@kernel.org>
Closes: https://lore.kernel.org/regressions/20250826220959.GA4119563@ax162/
Reported-by: Wei Fang <wei.fang@nxp.com>
Closes: https://lore.kernel.org/all/20250827093911.1218640-1-wei.fang@nxp.com/
Signed-off-by: Inochi Amaoto <inochiama@gmail.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Tested-by: Linux Kernel Functional Testing <lkft@linaro.org>
Tested-by: Jon Hunter <jonathanh@nvidia.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
---
Change from v1:
- https://lore.kernel.org/all/20250827062911.203106-1-inochiama@gmail.com/
1. Apply Tested-by, Reported-by and Tested-by from original post [1].
2. update mistake in the comments.

[1] https://lore.kernel.org/regressions/aK4O7Hl8NCVEMznB@monster/
---
 drivers/pci/msi/irqdomain.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/pci/msi/irqdomain.c b/drivers/pci/msi/irqdomain.c
index 50ccac32f4cf..cbdc83c064d4 100644
--- a/drivers/pci/msi/irqdomain.c
+++ b/drivers/pci/msi/irqdomain.c
@@ -154,6 +154,8 @@ static void cond_shutdown_parent(struct irq_data *data)

 	if (unlikely(info->flags & MSI_FLAG_PCI_MSI_STARTUP_PARENT))
 		irq_chip_shutdown_parent(data);
+	else if (unlikely(info->flags & MSI_FLAG_PCI_MSI_MASK_PARENT))
+		irq_chip_mask_parent(data);
 }

 static unsigned int cond_startup_parent(struct irq_data *data)
@@ -162,6 +164,9 @@ static unsigned int cond_startup_parent(struct irq_data *data)

 	if (unlikely(info->flags & MSI_FLAG_PCI_MSI_STARTUP_PARENT))
 		return irq_chip_startup_parent(data);
+	else if (unlikely(info->flags & MSI_FLAG_PCI_MSI_MASK_PARENT))
+		irq_chip_unmask_parent(data);
+
 	return 0;
 }

--
2.51.0