For supporting dynamic MSI-X vector allocation by PCI controllers, enabling
the flag MSI_FLAG_PCI_MSIX_ALLOC_DYN is not enough, msix_prepare_msi_desc()
to prepare the MSI descriptor is also needed.

Export pci_msix_prepare_desc() to allow PCI controllers to support dynamic
MSI-X vector allocation.

Signed-off-by: Shradha Gupta <redacted>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
Reviewed-by: Thomas Gleixner <redacted>
---
 Changes in v3
 * Improved the patch description by removing abbreviations
---
 drivers/pci/msi/irqdomain.c | 5 +++--
 include/linux/msi.h         | 2 ++
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/pci/msi/irqdomain.c b/drivers/pci/msi/irqdomain.c
index d7ba8795d60f..43129aa6d6c7 100644
--- a/drivers/pci/msi/irqdomain.c
+++ b/drivers/pci/msi/irqdomain.c

@@ -222,13 +222,14 @@ static void pci_irq_unmask_msix(struct irq_data *data)
 	pci_msix_unmask(irq_data_get_msi_desc(data));
 }
 
-static void pci_msix_prepare_desc(struct irq_domain *domain, msi_alloc_info_t *arg,
-				  struct msi_desc *desc)
+void pci_msix_prepare_desc(struct irq_domain *domain, msi_alloc_info_t *arg,
+			   struct msi_desc *desc)
 {
 	/* Don't fiddle with preallocated MSI descriptors */
 	if (!desc->pci.mask_base)
 		msix_prepare_msi_desc(to_pci_dev(desc->dev), desc);
 }
+EXPORT_SYMBOL_GPL(pci_msix_prepare_desc);
 
 static const struct msi_domain_template pci_msix_template = {
 	.chip = {

diff --git a/include/linux/msi.h b/include/linux/msi.h
index 86e42742fd0f..d5864d5e75c2 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h

@@ -691,6 +691,8 @@ struct irq_domain *pci_msi_create_irq_domain(struct fwnode_handle *fwnode,
 					     struct irq_domain *parent);
 u32 pci_msi_domain_get_msi_rid(struct irq_domain *domain, struct pci_dev *pdev);
 struct irq_domain *pci_msi_get_device_domain(struct pci_dev *pdev);
+void pci_msix_prepare_desc(struct irq_domain *domain, msi_alloc_info_t *arg,
+			   struct msi_desc *desc);
 #else /* CONFIG_PCI_MSI */
 static inline struct irq_domain *pci_msi_get_device_domain(struct pci_dev *pdev)
 {

-- 
2.34.1