linux-kernel - Re: [patch V2 18/36] genirq/msi: Add msi_device

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Date:   Tue, 7 Dec 2021 10:04:29 +0100
From:   Cédric Le Goater <clg@...d.org>
To:     Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>
CC:     Bjorn Helgaas <helgaas@...nel.org>, Marc Zygnier <maz@...nel.org>,
        Alex Williamson <alex.williamson@...hat.com>,
        Kevin Tian <kevin.tian@...el.com>,
        Jason Gunthorpe <jgg@...dia.com>,
        Megha Dey <megha.dey@...el.com>,
        Ashok Raj <ashok.raj@...el.com>, <linux-pci@...r.kernel.org>,
        <xen-devel@...ts.xenproject.org>, Juergen Gross <jgross@...e.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Will Deacon <will@...nel.org>,
        Santosh Shilimkar <ssantosh@...nel.org>,
        <iommu@...ts.linux-foundation.org>, <dmaengine@...r.kernel.org>,
        Stuart Yoder <stuyoder@...il.com>,
        Laurentiu Tudor <laurentiu.tudor@....com>,
        Nishanth Menon <nm@...com>, Tero Kristo <kristo@...nel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        Vinod Koul <vkoul@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Robin Murphy <robin.murphy@....com>,
        Sinan Kaya <okaya@...nel.org>
Subject: Re: [patch V2 18/36] genirq/msi: Add msi_device_data::properties

Hello Thomas,

On 12/6/21 23:39, Thomas Gleixner wrote:
> Add a properties field which allows core code to store information for easy
> retrieval in order to replace MSI descriptor fiddling.
> 
> Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
> ---
> V2: Add a setter function to prepare for future changes
> ---
>   include/linux/msi.h |   17 +++++++++++++++++
>   kernel/irq/msi.c    |   24 ++++++++++++++++++++++++
>   2 files changed, 41 insertions(+)
> 
> --- a/include/linux/msi.h
> +++ b/include/linux/msi.h
> @@ -4,6 +4,7 @@
>   
>   #include <linux/cpumask.h>
>   #include <linux/list.h>
> +#include <linux/bits.h>
>   #include <asm/msi.h>
>   
>   /* Dummy shadow structures if an architecture does not define them */
> @@ -153,6 +154,22 @@ struct msi_device_data {
>   
>   int msi_setup_device_data(struct device *dev);
>   
> +/* MSI device properties */
> +#define MSI_PROP_PCI_MSI		BIT(0)
> +#define MSI_PROP_PCI_MSIX		BIT(1)
> +#define MSI_PROP_64BIT			BIT(2)
> +
> +#ifdef CONFIG_GENERIC_MSI_IRQ
> +bool msi_device_has_property(struct device *dev, unsigned long prop);
> +void msi_device_set_properties(struct device *dev, unsigned long prop);
> +#else
> +static inline bool msi_device_has_property(struct device *dev, unsigned long prop)
> +{
> +	return false;
> +}
> +static inline void msi_device_set_properties(struct device *dev, unsigned long prop) { }
> +#endif
> +
>   /* Helpers to hide struct msi_desc implementation details */
>   #define msi_desc_to_dev(desc)		((desc)->dev)
>   #define dev_to_msi_list(dev)		(&(dev)->msi_list)
> --- a/kernel/irq/msi.c
> +++ b/kernel/irq/msi.c
> @@ -60,6 +60,30 @@ void free_msi_entry(struct msi_desc *ent
>   	kfree(entry);
>   }
>   
> +/**
> + * msi_device_set_properties - Set device specific MSI properties
> + * @dev:	Pointer to the device which is queried
> + * @prop:	Properties to set
> + */
> +void msi_device_set_properties(struct device *dev, unsigned long prop)
> +{
> +	if (WARN_ON_ONCE(!dev->msi.data))
> +		return ;
> +	dev->msi.data->properties = 0;
It would work better if the prop variable was used instead of 0.

With that fixed,

Reviewed-by: Cédric Le Goater <clg@...d.org>

Thanks,

C.

> +}
> +
> +/**
> + * msi_device_has_property - Check whether a device has a specific MSI property
> + * @dev:	Pointer to the device which is queried
> + * @prop:	Property to check for
> + */
> +bool msi_device_has_property(struct device *dev, unsigned long prop)
> +{
> +	if (!dev->msi.data)
> +		return false;
> +	return !!(dev->msi.data->properties & prop);
> +}
> +
>   void __get_cached_msi_msg(struct msi_desc *entry, struct msi_msg *msg)
>   {
>   	*msg = entry->msg;
>