Re: [PATCH v6 2/5] PCI: hv: Allow dynamic MSI-X vector allocation

[Bjorn Helgaas]

On Wed, Jun 11, 2025 at 07:10:15AM -0700, Shradha Gupta wrote:
> 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 <shradhagupta@xxxxxxxxxxxxxxxxxxx>
> Reviewed-by: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
> Reviewed-by: Saurabh Sengar <ssengar@xxxxxxxxxxxxxxxxxxx>

Again, if you need it:

Acked-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx>

> ---
>  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 deletion(-)
> 
> diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
> index ef5d655a0052..86ca041bf74a 100644
> --- a/drivers/pci/controller/pci-hyperv.c
> +++ b/drivers/pci/controller/pci-hyperv.c
> @@ -2119,6 +2119,7 @@ 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,
>  };
>  
>  /**
> @@ -2140,7 +2141,7 @@ 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
>