Allow dynamic MSI-X vector allocation for pci_hyperv PCI controller
by adding support for the flag MSI_FLAG_PCI_MSIX_ALLOC_DYN and using
pci_msix_prepare_desc() to prepare the MSI-X descriptors.

Feature support added for both x86 and ARM64

Signed-off-by: Shradha Gupta <redacted>
Reviewed-by: Haiyang Zhang <haiyangz@microsoft.com>
---
 Changes in v4:
 * use the same prepare_desc() callback for arm and x86
---
 Changes in v3:
 * Add arm64 support
---
 Changes in v2:
 * split the patch to keep changes in PCI and pci_hyperv controller
   seperate
 * replace strings "pci vectors" by "MSI-X vectors"
---
 drivers/pci/controller/pci-hyperv.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletions(-)

diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index ac27bda5ba26..0c790f35ad0e 100644
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c

@@ -2063,6 +2063,7 @@ 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	= pci_msix_prepare_desc,
 };
 
 /**

@@ -2084,7 +2085,7 @@ 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;

-- 
2.34.1