linux-kernel - Re: [patch RFC 34/38] x86/msi: Let pci_msi

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Date:   Tue, 25 Aug 2020 15:24:19 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        linux-pci@...r.kernel.org, linux-hyperv@...r.kernel.org,
        Joerg Roedel <joro@...tes.org>,
        iommu@...ts.linux-foundation.org,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Jon Derrick <jonathan.derrick@...el.com>,
        Lu Baolu <baolu.lu@...ux.intel.com>,
        Wei Liu <wei.liu@...nel.org>,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>,
        Steve Wahl <steve.wahl@....com>,
        Dimitri Sivanich <sivanich@....com>,
        Russ Anderson <rja@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        xen-devel@...ts.xenproject.org, Juergen Gross <jgross@...e.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        Stefano Stabellini <sstabellini@...nel.org>,
        Marc Zyngier <maz@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Megha Dey <megha.dey@...el.com>,
        Jason Gunthorpe <jgg@...lanox.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        Jacob Pan <jacob.jun.pan@...el.com>,
        Baolu Lu <baolu.lu@...el.com>,
        Kevin Tian <kevin.tian@...el.com>,
        Dan Williams <dan.j.williams@...el.com>
Subject: Re: [patch RFC 34/38] x86/msi: Let pci_msi_prepare() handle non-PCI
 MSI

On Fri, Aug 21, 2020 at 02:24:58AM +0200, Thomas Gleixner wrote:
> Rename it to x86_msi_prepare() and handle the allocation type setup
> depending on the device type.

I see what you're doing, but the subject reads a little strangely
("pci_msi_prepare() handling non-PCI" stuff) since it doesn't mention
the rename.  Maybe not practical or worthwhile to split into a rename
+ make generic, I dunno.

> Add a new arch_msi_prepare define which will be utilized by the upcoming
> device MSI support. Define it to NULL if not provided by an architecture in
> the generic MSI header.
> 
> One arch specific function for MSI support is truly enough.
> 
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> Cc: linux-pci@...r.kernel.org
> Cc: linux-hyperv@...r.kernel.org
> ---
>  arch/x86/include/asm/msi.h          |    4 +++-
>  arch/x86/kernel/apic/msi.c          |   27 ++++++++++++++++++++-------
>  drivers/pci/controller/pci-hyperv.c |    2 +-
>  include/linux/msi.h                 |    4 ++++
>  4 files changed, 28 insertions(+), 9 deletions(-)
> 
> --- a/arch/x86/include/asm/msi.h
> +++ b/arch/x86/include/asm/msi.h
> @@ -6,7 +6,9 @@
>  
>  typedef struct irq_alloc_info msi_alloc_info_t;
>  
> -int pci_msi_prepare(struct irq_domain *domain, struct device *dev, int nvec,
> +int x86_msi_prepare(struct irq_domain *domain, struct device *dev, int nvec,
>  		    msi_alloc_info_t *arg);
>  
> +#define arch_msi_prepare		x86_msi_prepare
> +
>  #endif /* _ASM_X86_MSI_H */
> --- a/arch/x86/kernel/apic/msi.c
> +++ b/arch/x86/kernel/apic/msi.c
> @@ -182,26 +182,39 @@ static struct irq_chip pci_msi_controlle
>  	.flags			= IRQCHIP_SKIP_SET_WAKE,
>  };
>  
> -int pci_msi_prepare(struct irq_domain *domain, struct device *dev, int nvec,
> -		    msi_alloc_info_t *arg)
> +static void pci_msi_prepare(struct device *dev, msi_alloc_info_t *arg)
>  {
> -	struct pci_dev *pdev = to_pci_dev(dev);
> -	struct msi_desc *desc = first_pci_msi_entry(pdev);
> +	struct msi_desc *desc = first_msi_entry(dev);
>  
> -	init_irq_alloc_info(arg, NULL);
>  	if (desc->msi_attrib.is_msix) {
>  		arg->type = X86_IRQ_ALLOC_TYPE_PCI_MSIX;
>  	} else {
>  		arg->type = X86_IRQ_ALLOC_TYPE_PCI_MSI;
>  		arg->flags |= X86_IRQ_ALLOC_CONTIGUOUS_VECTORS;
>  	}
> +}
> +
> +static void dev_msi_prepare(struct device *dev, msi_alloc_info_t *arg)
> +{
> +	arg->type = X86_IRQ_ALLOC_TYPE_DEV_MSI;
> +}
> +
> +int x86_msi_prepare(struct irq_domain *domain, struct device *dev, int nvec,
> +		    msi_alloc_info_t *arg)
> +{
> +	init_irq_alloc_info(arg, NULL);
> +
> +	if (dev_is_pci(dev))
> +		pci_msi_prepare(dev, arg);
> +	else
> +		dev_msi_prepare(dev, arg);
>  
>  	return 0;
>  }
> -EXPORT_SYMBOL_GPL(pci_msi_prepare);
> +EXPORT_SYMBOL_GPL(x86_msi_prepare);
>  
>  static struct msi_domain_ops pci_msi_domain_ops = {
> -	.msi_prepare	= pci_msi_prepare,
> +	.msi_prepare	= x86_msi_prepare,
>  };
>  
>  static struct msi_domain_info pci_msi_domain_info = {
> --- a/drivers/pci/controller/pci-hyperv.c
> +++ b/drivers/pci/controller/pci-hyperv.c
> @@ -1532,7 +1532,7 @@ static struct irq_chip hv_msi_irq_chip =
>  };
>  
>  static struct msi_domain_ops hv_msi_ops = {
> -	.msi_prepare	= pci_msi_prepare,
> +	.msi_prepare	= arch_msi_prepare,
>  	.msi_free	= hv_msi_free,
>  };
>  
> --- a/include/linux/msi.h
> +++ b/include/linux/msi.h
> @@ -430,4 +430,8 @@ static inline struct irq_domain *pci_msi
>  }
>  #endif /* CONFIG_PCI_MSI_IRQ_DOMAIN */
>  
> +#ifndef arch_msi_prepare
> +# define arch_msi_prepare	NULL
> +#endif
> +
>  #endif /* LINUX_MSI_H */
>