linux-kernel - Re: [patch RFC 21/38] PCI: MSI: Provide pci_dev_has_special_msi

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Message-ID: <20200825201634.GA1924972@bjorn-Precision-5520>
Date:   Tue, 25 Aug 2020 15:16:34 -0500
From:   Bjorn Helgaas <helgaas@...nel.org>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
        Bjorn Helgaas <bhelgaas@...gle.com>, linux-pci@...r.kernel.org,
        Joerg Roedel <joro@...tes.org>,
        iommu@...ts.linux-foundation.org, linux-hyperv@...r.kernel.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>,
        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 21/38] PCI: MSI: Provide
 pci_dev_has_special_msi_domain() helper

On Fri, Aug 21, 2020 at 02:24:45AM +0200, Thomas Gleixner wrote:
> Provide a helper function to check whether a PCI device is handled by a
> non-standard PCI/MSI domain. This will be used to exclude such devices
> which hang of a special bus, e.g. VMD, to be excluded from the irq domain
> override in irq remapping.
> 
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> Cc: Bjorn Helgaas <bhelgaas@...gle.com>
> Cc: linux-pci@...r.kernel.org

Acked-by: Bjorn Helgaas <bhelgaas@...gle.com>

s|PCI: MSI:|PCI/MSI:| in the subject if feasible.

> ---
>  drivers/pci/msi.c   |   22 ++++++++++++++++++++++
>  include/linux/msi.h |    1 +
>  2 files changed, 23 insertions(+)
> 
> --- a/drivers/pci/msi.c
> +++ b/drivers/pci/msi.c
> @@ -1553,4 +1553,26 @@ struct irq_domain *pci_msi_get_device_do
>  					     DOMAIN_BUS_PCI_MSI);
>  	return dom;
>  }
> +
> +/**
> + * pci_dev_has_special_msi_domain - Check whether the device is handled by
> + *				    a non-standard PCI-MSI domain
> + * @pdev:	The PCI device to check.
> + *
> + * Returns: True if the device irqdomain or the bus irqdomain is
> + * non-standard PCI/MSI.
> + */
> +bool pci_dev_has_special_msi_domain(struct pci_dev *pdev)
> +{
> +	struct irq_domain *dom = dev_get_msi_domain(&pdev->dev);
> +
> +	if (!dom)
> +		dom = dev_get_msi_domain(&pdev->bus->dev);
> +
> +	if (!dom)
> +		return true;
> +
> +	return dom->bus_token != DOMAIN_BUS_PCI_MSI;
> +}
> +
>  #endif /* CONFIG_PCI_MSI_IRQ_DOMAIN */
> --- a/include/linux/msi.h
> +++ b/include/linux/msi.h
> @@ -374,6 +374,7 @@ int pci_msi_domain_check_cap(struct irq_
>  			     struct msi_domain_info *info, struct device *dev);
>  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);
> +bool pci_dev_has_special_msi_domain(struct pci_dev *pdev);
>  #else
>  static inline struct irq_domain *pci_msi_get_device_domain(struct pci_dev *pdev)
>  {
>