For supporting dynamic MSI vector allocation by pci controllers, enabling
the flag MSI_FLAG_PCI_MSIX_ALLOC_DYN is not enough, msix_prepare_msi_desc()
to prepare the desc is needed. Export pci_msix_prepare_desc() to allow pci
controllers like pci-hyperv to support dynamic MSI vector allocation.
Also, add the flag MSI_FLAG_PCI_MSIX_ALLOC_DYN and use
pci_msix_prepare_desc() in pci_hyperv controller

Signed-off-by: Shradha Gupta <shradhagu...@linux.microsoft.com>
Reviewed-by: Haiyang Zhang <haiya...@microsoft.com>
Reviewed-by: Long Li <lon...@microsoft.com>
---
 drivers/pci/controller/pci-hyperv.c | 7 +++++--
 drivers/pci/msi/irqdomain.c         | 5 +++--
 include/linux/msi.h                 | 2 ++
 3 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/controller/pci-hyperv.c 
b/drivers/pci/controller/pci-hyperv.c
index ac27bda5ba26..f2fa6bdb6bb8 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -598,7 +598,8 @@ static unsigned int hv_msi_get_int_vector(struct irq_data 
*data)
        return cfg->vector;
 }
 
-#define hv_msi_prepare         pci_msi_prepare
+#define hv_msi_prepare                 pci_msi_prepare
+#define hv_msix_prepare_desc           pci_msix_prepare_desc
 
 /**
  * hv_arch_irq_unmask() - "Unmask" the IRQ by setting its current
@@ -727,6 +728,7 @@ static void hv_arch_irq_unmask(struct irq_data *data)
 #define FLOW_HANDLER           NULL
 #define FLOW_NAME              NULL
 #define hv_msi_prepare         NULL
+#define hv_msix_prepare_desc   NULL
 
 struct hv_pci_chip_data {
        DECLARE_BITMAP(spi_map, HV_PCI_MSI_SPI_NR);
@@ -2063,6 +2065,7 @@ static struct irq_chip hv_msi_irq_chip = {
 static struct msi_domain_ops hv_msi_ops = {
        .msi_prepare    = hv_msi_prepare,
        .msi_free       = hv_msi_free,
+       .prepare_desc   = hv_msix_prepare_desc,
 };
 
 /**
@@ -2084,7 +2087,7 @@ static int hv_pcie_init_irq_domain(struct 
hv_pcibus_device *hbus)
        hbus->msi_info.ops = &hv_msi_ops;
        hbus->msi_info.flags = (MSI_FLAG_USE_DEF_DOM_OPS |
                MSI_FLAG_USE_DEF_CHIP_OPS | MSI_FLAG_MULTI_PCI_MSI |
-               MSI_FLAG_PCI_MSIX);
+               MSI_FLAG_PCI_MSIX | MSI_FLAG_PCI_MSIX_ALLOC_DYN);
        hbus->msi_info.handler = FLOW_HANDLER;
        hbus->msi_info.handler_name = FLOW_NAME;
        hbus->msi_info.data = hbus;
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


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