linux-kernel - Re: [PATCH v2 1/3] PCI: Export pci_msix_prepare

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Message-ID: <20250425163748.GA546623@bhelgaas>
Date: Fri, 25 Apr 2025 11:37:48 -0500
From: Bjorn Helgaas <helgaas@...nel.org>
To: Shradha Gupta <shradhagupta@...ux.microsoft.com>
Cc: linux-hyperv@...r.kernel.org, linux-pci@...r.kernel.org,
	linux-kernel@...r.kernel.org, Nipun Gupta <nipun.gupta@....com>,
	Yury Norov <yury.norov@...il.com>, Jason Gunthorpe <jgg@...pe.ca>,
	Jonathan Cameron <Jonathan.Cameron@...ei.com>,
	Anna-Maria Behnsen <anna-maria@...utronix.de>,
	Kevin Tian <kevin.tian@...el.com>, Long Li <longli@...rosoft.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Bjorn Helgaas <bhelgaas@...gle.com>, Rob Herring <robh@...nel.org>,
	Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
	Krzysztof Wilczyński <kw@...ux.com>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Dexuan Cui <decui@...rosoft.com>, Wei Liu <wei.liu@...nel.org>,
	Haiyang Zhang <haiyangz@...rosoft.com>,
	"K. Y. Srinivasan" <kys@...rosoft.com>,
	Andrew Lunn <andrew+netdev@...n.ch>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	Konstantin Taranov <kotaranov@...rosoft.com>,
	Simon Horman <horms@...nel.org>, Leon Romanovsky <leon@...nel.org>,
	Maxim Levitsky <mlevitsk@...hat.com>,
	Erni Sri Satya Vennela <ernis@...ux.microsoft.com>,
	Peter Zijlstra <peterz@...radead.org>, netdev@...r.kernel.org,
	linux-rdma@...r.kernel.org, Paul Rosswurm <paulros@...rosoft.com>,
	Shradha Gupta <shradhagupta@...rosoft.com>
Subject: Re: [PATCH v2 1/3] PCI: Export pci_msix_prepare_desc() for dynamic
 MSI-X alloc

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 <shradhagupta@...ux.microsoft.com>
> Reviewed-by: Haiyang Zhang <haiyangz@...rosoft.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:".

> ---
>  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
>