RE: [PATCH] PCI: Fix build error when CONFIG_PCI_MSI disabled

[Tian, Kevin]

> From: Chatre, Reinette <reinette.chatre@xxxxxxxxx>
> Sent: Friday, February 10, 2023 5:49 AM
> 
> pci_msix_alloc_irq_at() and pci_msix_free_irq() are not
> declared when CONFIG_PCI_MSI is disabled.
> 
> Users of these two calls do not yet exist but when users
> do appear (shown below is an attempt to use the new API
> in vfio-pci) the following errors will be encountered when
> compiling with CONFIG_PCI_MSI disabled:
> drivers/vfio/pci/vfio_pci_intrs.c:461:4: error: implicit declaration of\
>         function 'pci_msix_free_irq' is invalid in C99\
>         [-Werror,-Wimplicit-function-declaration]
>                            pci_msix_free_irq(pdev, msix_map);
>                            ^
>    drivers/vfio/pci/vfio_pci_intrs.c:461:4: note: did you mean
> 'pci_ims_free_irq'?
>    include/linux/pci.h:2516:6: note: 'pci_ims_free_irq' declared here
>    void pci_ims_free_irq(struct pci_dev *pdev, struct msi_map map);
>         ^
> drivers/vfio/pci/vfio_pci_intrs.c:511:15: error: implicit declaration of\
>         function 'pci_msix_alloc_irq_at' is invalid in C99\
>         [-Werror,-Wimplicit-function-declaration]
>                    msix_map = pci_msix_alloc_irq_at(pdev, vector, NULL);
>                                       ^
>    drivers/vfio/pci/vfio_pci_intrs.c:511:15: note: did you mean
> 'pci_ims_alloc_irq'?
>    include/linux/pci.h:2514:16: note: 'pci_ims_alloc_irq' declared here
>    struct msi_map pci_ims_alloc_irq(struct pci_dev *pdev,\
>                                     union msi_instance_cookie *icookie,
> 
> Provide definitions for pci_msix_alloc_irq_at() and pci_msix_free_irq() in
> preparation for users that need to compile when CONFIG_PCI_MSI is
> disabled.
> 
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> Signed-off-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>

Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>