[patch 34/39] PCI/MSI: Reject multi-MSI early

[Jason Gunthorpe]

On Fri, Nov 11, 2022 at 02:55:09PM +0100, Thomas Gleixner wrote:
> When hierarchical MSI interrupt domains are enabled then there is no point
> to do tons of work and detect the missing support for multi-MSI late in the
> allocation path.
> 
> Just query the domain feature flags right away. The query function is going
> to be used for other purposes later and has a mode argument which influences
> the result:
> 
>   ALLOW_LEGACY returns true when:
>      - there is no irq domain attached (legacy support)
>      - there is a irq domain attached which has the feature flag set
> 
>   DENY_LEGACY returns only true when:
>      - there is a irq domain attached which has the feature flag set
> 
> This allows to use the function universally without ifdeffery in the
> calling code.
> 
> Signed-off-by: Thomas Gleixner <tglx at linutronix.de>
> ---
>  drivers/pci/msi/irqdomain.c |   22 ++++++++++++++++++++++
>  drivers/pci/msi/msi.c       |    4 ++++
>  drivers/pci/msi/msi.h       |    9 +++++++++
>  3 files changed, 35 insertions(+)

Reviewed-by: Jason Gunthorpe <jgg at nvidia.com>

Jason