Re: [patch 22/33] genirq/msi: Provide MSI_FLAG_MSIX_ALLOC_DYN

[Jason Gunthorpe]

On Fri, Nov 11, 2022 at 02:58:46PM +0100, Thomas Gleixner wrote:
> Provide a new MSI feature flag in preparation for dynamic MSIX allocation
> after the initial MSI-X enable has been done.
> 
> This needs to be an explicit MSI interrupt domain feature because quite
> some implementations (both interrupt domains and legacy allocation mode)
> have clear expectations that the allocation code is only invoked when MSI-X
> is about to be enabled. They either talk to hypervisors or do some other
> work and are not prepared to be invoked on an already MSI-X enabled device.
> 
> This is also explicit MSI-X only because rewriting the size of the MSI
> entries is only possible when disabling MSI which in turn might cause lost
> interrupts on the device.
> 
> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> ---
>  include/linux/msi.h |    3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)

Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>

Jason