linux-kernel - Re: [PATCH] vfio: cdx: Fix missing GENERIC_MSI

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Message-ID: <20250717134014.16b97da5.alex.williamson@redhat.com>
Date: Thu, 17 Jul 2025 13:40:14 -0600
From: Alex Williamson <alex.williamson@...hat.com>
To: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc: Nipun Gupta <nipun.gupta@....com>, Nikhil Agarwal
 <nikhil.agarwal@....com>, Pieter Jansen van Vuuren
 <pieter.jansen-van-vuuren@....com>, kvm@...r.kernel.org,
 linux-kernel@...r.kernel.org, Randy Dunlap <rdunlap@...radead.org>,
 stable@...r.kernel.org
Subject: Re: [PATCH] vfio: cdx: Fix missing GENERIC_MSI_IRQ on compile test

On Thu, 17 Jul 2025 11:10:54 +0200
Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org> wrote:

> VFIO_CDX driver uses msi_domain_alloc_irqs() which is provided by
> non-user-visible GENERIC_MSI_IRQ, thus it should select that option
> directly.
> 
> VFIO_CDX depends on CDX_BUS, which also will select GENERIC_MSI_IRQ
> (separate fix), nevertheless driver should poll what is being used there
> instead of relying on bus Kconfig.

This seems like a recipe for an explosion of Kconfig noise.  If the bus
fundamentally depends on a config option, as proposed in the separate
fix, I don't see that a driver dependent on that bus needs to duplicate
the config selections.  IMO this is sufficiently fixed updating
drivers/cdx/{Kconfig,Makefile}.  Thanks,

Alex
 
> Without the fix on CDX_BUS compile test fails:
> 
>   drivers/vfio/cdx/intr.c: In function ‘vfio_cdx_msi_enable’:
>   drivers/vfio/cdx/intr.c:41:15: error: implicit declaration of function ‘msi_domain_alloc_irqs’;
>     did you mean ‘irq_domain_alloc_irqs’? [-Wimplicit-function-declaration]
> 
> Reported-by: Randy Dunlap <rdunlap@...radead.org>
> Closes: https://lore.kernel.org/r/4a6fd102-f8e0-42f3-b789-6e3340897032@infradead.org/
> Fixes: 848e447e000c ("vfio/cdx: add interrupt support")
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
> ---
>  drivers/vfio/cdx/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/vfio/cdx/Kconfig b/drivers/vfio/cdx/Kconfig
> index e6de0a0caa32..90cf3dee5dba 100644
> --- a/drivers/vfio/cdx/Kconfig
> +++ b/drivers/vfio/cdx/Kconfig
> @@ -9,6 +9,7 @@ config VFIO_CDX
>  	tristate "VFIO support for CDX bus devices"
>  	depends on CDX_BUS
>  	select EVENTFD
> +	select GENERIC_MSI_IRQ
>  	help
>  	  Driver to enable VFIO support for the devices on CDX bus.
>  	  This is required to make use of CDX devices present in