Re: [PATCH] PCI/MSI: Provide stubs for IMS functions

[Bjorn Helgaas]

On Tue, Oct 17, 2023 at 10:56:38AM -0700, Reinette Chatre wrote:
> The IMS related functions (pci_create_ims_domain(),
> pci_ims_alloc_irq(), and pci_ims_free_irq()) are not declared
> when CONFIG_PCI_MSI is disabled.
> 
> Provide definitions of these functions for use when callers
> are compiled with CONFIG_PCI_MSI disabled.
> 
> Fixes: 0194425af0c8 ("PCI/MSI: Provide IMS (Interrupt Message Store) support")
> Fixes: c9e5bea27383 ("PCI/MSI: Provide pci_ims_alloc/free_irq()")
> Signed-off-by: Reinette Chatre <reinette.chatre@xxxxxxxxx>
> Cc: stable@xxxxxxxxxxxxxxx      # v6.2+

Applied to pci/misc for v6.7, thanks!

> ---
> 
> This is a preparatory patch for the first caller of these
> functions (VFIO) for which work is in progress:
> https://lore.kernel.org/lkml/cover.1696609476.git.reinette.chatre@xxxxxxxxx/
> 
> checkpatch.pl complains about the usage of ENOSYS but
> it does appear to be the custom.
> 
>  include/linux/pci.h | 34 ++++++++++++++++++++++++++--------
>  1 file changed, 26 insertions(+), 8 deletions(-)
> 
> diff --git a/include/linux/pci.h b/include/linux/pci.h
> index 8c7c2c3c6c65..b56417276042 100644
> --- a/include/linux/pci.h
> +++ b/include/linux/pci.h
> @@ -1624,6 +1624,8 @@ struct msix_entry {
>  	u16	entry;	/* Driver uses to specify entry, OS writes */
>  };
>  
> +struct msi_domain_template;
> +
>  #ifdef CONFIG_PCI_MSI
>  int pci_msi_vec_count(struct pci_dev *dev);
>  void pci_disable_msi(struct pci_dev *dev);
> @@ -1656,6 +1658,11 @@ void pci_msix_free_irq(struct pci_dev *pdev, struct msi_map map);
>  void pci_free_irq_vectors(struct pci_dev *dev);
>  int pci_irq_vector(struct pci_dev *dev, unsigned int nr);
>  const struct cpumask *pci_irq_get_affinity(struct pci_dev *pdev, int vec);
> +bool pci_create_ims_domain(struct pci_dev *pdev, const struct msi_domain_template *template,
> +			   unsigned int hwsize, void *data);
> +struct msi_map pci_ims_alloc_irq(struct pci_dev *pdev, union msi_instance_cookie *icookie,
> +				 const struct irq_affinity_desc *affdesc);
> +void pci_ims_free_irq(struct pci_dev *pdev, struct msi_map map);
>  
>  #else
>  static inline int pci_msi_vec_count(struct pci_dev *dev) { return -ENOSYS; }
> @@ -1719,6 +1726,25 @@ static inline const struct cpumask *pci_irq_get_affinity(struct pci_dev *pdev,
>  {
>  	return cpu_possible_mask;
>  }
> +
> +static inline bool pci_create_ims_domain(struct pci_dev *pdev,
> +					 const struct msi_domain_template *template,
> +					 unsigned int hwsize, void *data)
> +{ return false; }
> +
> +static inline struct msi_map pci_ims_alloc_irq(struct pci_dev *pdev,
> +					       union msi_instance_cookie *icookie,
> +					       const struct irq_affinity_desc *affdesc)
> +{
> +	struct msi_map map = { .index = -ENOSYS, };
> +
> +	return map;
> +}
> +
> +static inline void pci_ims_free_irq(struct pci_dev *pdev, struct msi_map map)
> +{
> +}
> +
>  #endif
>  
>  /**
> @@ -2616,14 +2642,6 @@ static inline bool pci_is_thunderbolt_attached(struct pci_dev *pdev)
>  void pci_uevent_ers(struct pci_dev *pdev, enum  pci_ers_result err_type);
>  #endif
>  
> -struct msi_domain_template;
> -
> -bool pci_create_ims_domain(struct pci_dev *pdev, const struct msi_domain_template *template,
> -			   unsigned int hwsize, void *data);
> -struct msi_map pci_ims_alloc_irq(struct pci_dev *pdev, union msi_instance_cookie *icookie,
> -				 const struct irq_affinity_desc *affdesc);
> -void pci_ims_free_irq(struct pci_dev *pdev, struct msi_map map);
> -
>  #include <linux/dma-mapping.h>
>  
>  #define pci_printk(level, pdev, fmt, arg...) \
> -- 
> 2.34.1
>