Re: [PATCH v2 1/3] PCI: Export pci_msix_prepare_desc() for dynamic MSI-X alloc

[Shradha Gupta]

On Fri, Apr 25, 2025 at 11:37:48AM -0500, Bjorn Helgaas wrote:
> On Fri, Apr 25, 2025 at 03:53:57AM -0700, Shradha Gupta wrote:
> > For supporting dynamic MSI-X 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 also needed.
> > 
> > Export pci_msix_prepare_desc() to allow PCI controllers to support dynamic
> > MSI-X vector allocation.
> > 
> > Signed-off-by: Shradha Gupta <shradhagu...@linux.microsoft.com>
> > Reviewed-by: Haiyang Zhang <haiya...@microsoft.com>
> 
> Thanks for the update and for splitting this from the hv driver
> update.  Will watch for Thomas's ack here.
> 
> For future postings, you might consider limiting the "To:" line to
> people you expect to actually act on the patch, and moving the rest to
> "Cc:".

Thanks Bjorn, Noted.
> 
> > ---
> >  drivers/pci/msi/irqdomain.c | 5 +++--
> >  include/linux/msi.h         | 2 ++
> >  2 files changed, 5 insertions(+), 2 deletions(-)
> > 
> > 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
> >