The following commit has been merged into the irq/urgent branch of tip:

Commit-ID:     9cc82d99b13c1ad04e3dff9182b7953a8dba10b6
Gitweb:        https://git.kernel.org/tip/9cc82d99b13c1ad04e3dff9182b7953a8dba10b6
Author:        Marc Zyngier <maz@kernel.org>
AuthorDate:    Tue, 03 Jun 2025 15:18:01 +01:00
Committer:     Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Wed, 04 Jun 2025 11:19:25 +02:00

PCI/MSI: Size device MSI domain with the maximum number of vectors

Zenghui reports that since 1396e89e09f0 ("genirq/msi: Move prepare() call
to per-device allocation"), his Multi-MSI capable device isn't working
anymore.

This is a consequence of 15c72f824b32 ("PCI/MSI: Add support for per device
MSI[X] domains"), which always creates a MSI domain of size 1, even in the
presence of Multi-MSI.

While this was somehow working until then, moving the .prepare() call ends
up sizing the ITS table with a tiny value for this device, and making the
endpoint driver unhappy.

Instead, always create the domain and call the .prepare() helper with the
maximum expected size.

Fixes: 1396e89e09f0 ("genirq/msi: Move prepare() call to per-device allocation")
Fixes: 15c72f824b32 ("PCI/MSI: Add support for per device MSI[X] domains")
Reported-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Zenghui Yu <yuzenghui@huawei.com>
Reviewed-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Link: https://lore.kernel.org/all/20250603141801.915305-1-maz@kernel.org
Closes: https://lore.kernel.org/r/0b1d7aec-1eac-a9cd-502a-339e216e08a1@huawei.com
---
 drivers/pci/msi/irqdomain.c | 5 +++--
 drivers/pci/msi/msi.c       | 8 ++++----
 drivers/pci/msi/msi.h       | 2 +-
 3 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/pci/msi/irqdomain.c b/drivers/pci/msi/irqdomain.c
index d7ba879..c051527 100644
--- a/drivers/pci/msi/irqdomain.c
+++ b/drivers/pci/msi/irqdomain.c
@@ -271,6 +271,7 @@ static bool pci_create_device_domain(struct pci_dev *pdev, const struct msi_doma
 /**
  * pci_setup_msi_device_domain - Setup a device MSI interrupt domain
  * @pdev:	The PCI device to create the domain on
+ * @hwsize:	The maximum number of MSI vectors
  *
  * Return:
  *  True when:
@@ -287,7 +288,7 @@ static bool pci_create_device_domain(struct pci_dev *pdev, const struct msi_doma
  *	- The device is removed
  *	- MSI is disabled and a MSI-X domain is created
  */
-bool pci_setup_msi_device_domain(struct pci_dev *pdev)
+bool pci_setup_msi_device_domain(struct pci_dev *pdev, unsigned int hwsize)
 {
 	if (WARN_ON_ONCE(pdev->msix_enabled))
 		return false;
@@ -297,7 +298,7 @@ bool pci_setup_msi_device_domain(struct pci_dev *pdev)
 	if (pci_match_device_domain(pdev, DOMAIN_BUS_PCI_DEVICE_MSIX))
 		msi_remove_device_irq_domain(&pdev->dev, MSI_DEFAULT_DOMAIN);
 
-	return pci_create_device_domain(pdev, &pci_msi_template, 1);
+	return pci_create_device_domain(pdev, &pci_msi_template, hwsize);
 }
 
 /**
diff --git a/drivers/pci/msi/msi.c b/drivers/pci/msi/msi.c
index d6ce040..6ede55a 100644
--- a/drivers/pci/msi/msi.c
+++ b/drivers/pci/msi/msi.c
@@ -439,16 +439,16 @@ int __pci_enable_msi_range(struct pci_dev *dev, int minvec, int maxvec,
 	if (nvec < minvec)
 		return -ENOSPC;
 
-	if (nvec > maxvec)
-		nvec = maxvec;
-
 	rc = pci_setup_msi_context(dev);
 	if (rc)
 		return rc;
 
-	if (!pci_setup_msi_device_domain(dev))
+	if (!pci_setup_msi_device_domain(dev, nvec))
 		return -ENODEV;
 
+	if (nvec > maxvec)
+		nvec = maxvec;
+
 	for (;;) {
 		if (affd) {
 			nvec = irq_calc_affinity_vectors(minvec, nvec, affd);
diff --git a/drivers/pci/msi/msi.h b/drivers/pci/msi/msi.h
index fc70b60..0b420b3 100644
--- a/drivers/pci/msi/msi.h
+++ b/drivers/pci/msi/msi.h
@@ -107,7 +107,7 @@ enum support_mode {
 };
 
 bool pci_msi_domain_supports(struct pci_dev *dev, unsigned int feature_mask, enum support_mode mode);
-bool pci_setup_msi_device_domain(struct pci_dev *pdev);
+bool pci_setup_msi_device_domain(struct pci_dev *pdev, unsigned int hwsize);
 bool pci_setup_msix_device_domain(struct pci_dev *pdev, unsigned int hwsize);
 
 /* Legacy (!IRQDOMAIN) fallbacks */