Re: [PATCH] powerpc/pci: Initialize msi_addr_mask for OF-created PCI devices

On 2/19/26 11:01 PM, Bjorn Helgaas wrote:

[+cc sparc folks, PCI enumeration via OF likely broken]

On Tue, Feb 17, 2026 at 11:15:26PM +0530, Nilay Shroff wrote:

quoted

Recent changes [1] replaced the use of no_64bit_msi with msi_addr_mask.
As a result, msi_addr_mask is now expected to be initialized to
DMA_BIT_MASK(64) when a pci_dev is set up. However, this initialization
was missed on powerpc due to differences in the device initialization
path compared to other architectures. Due to this, now pci device probe
method fails on powerpc system.

s/pci/PCI/ to match below.

Ack

quoted

On powerpc systems, struct pci_dev instances are created from device
tree nodes via of_create_pci_dev(). Because msi_addr_mask was not
initialized there, it remained zero. Later, during MSI setup,
msi_verify_entries() validates the programmed MSI address against
pdev->msi_addr_mask. Since the mask was not set correctly, the
validation fails, causing PCI driver probe failures for devices on
powerpc systems.

Initialize pdev->msi_addr_mask to DMA_BIT_MASK(64) in
of_create_pci_dev() so that MSI address validation succeeds and device
probe works as expected.

[1] https://lore.kernel.org/all/20260129-pci-msi-addr-mask-v4-0-70da998f2750@iscas.ac.cn/ (local)

Fixes: 386ced19e9a3 ("PCI/MSI: Convert the boolean no_64bit_msi flag to a DMA address mask")
Signed-off-by: Nilay Shroff <redacted>

Looks like this and a similar sparc fix need to be in v7.0.  Would be
great if they could make v7.0-rc1 (Sunday), but that's pretty close.

Thomas, you merged 386ced19e9a3.  I'm happy to merge the powerpc and
sparc fixes, given acks from you and the powerpc & sparc folks, or
feel free to take them yourself.

quoted

---
 arch/powerpc/kernel/pci_of_scan.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/powerpc/kernel/pci_of_scan.c b/arch/powerpc/kernel/pci_of_scan.c
index 756043dd06e9..26ec97ce6b40 100644
--- a/arch/powerpc/kernel/pci_of_scan.c
+++ b/arch/powerpc/kernel/pci_of_scan.c

@@ -211,6 +211,12 @@ struct pci_dev *of_create_pci_dev(struct device_node *node,
 	dev->current_state = PCI_UNKNOWN;	/* unknown power state */
 	dev->error_state = pci_channel_io_normal;
 	dev->dma_mask = 0xffffffff;

It's typical to add a blank line between the code above and the
comment below, as was done in 386ced19e9a3.

Okay will fix this in v2.

quoted

+	/*
+	 * Assume 64-bit addresses for MSI initially. Will be changed to 32-bit
+	 * if MSI (rather than MSI-X) capability does not have
+	 * PCI_MSI_FLAGS_64BIT. Can also be overridden by driver.
+	 */
+	dev->msi_addr_mask = DMA_BIT_MASK(64);
 
 	/* Early fixups, before probing the BARs */
 	pci_fixup_device(pci_fixup_early, dev);
-- 
2.52.0

Thanks,
--Nilay