Re: [PATCH v3] xen-pciback: Consider INTx disabled when MSI/MSI-X is enabled

[Juergen Gross <jgross@suse.com>]

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On 18.11.22 16:49, Marek Marczykowski-Górecki wrote:
> Linux enables MSI-X before disabling INTx, but keeps MSI-X masked until
> the table is filled. Then it disables INTx just before clearing MASKALL
> bit. Currently this approach is rejected by xen-pciback.
> According to the PCIe spec, device cannot use INTx when MSI/MSI-X is
> enabled (in other words: enabling MSI/MSI-X implicitly disables INTx).
> 
> Change the logic to consider INTx disabled if MSI/MSI-X is enabled. This
> applies to three places:
>   - checking currently enabled interrupts type,
>   - transition to MSI/MSI-X - where INTx would be implicitly disabled,
>   - clearing INTx disable bit - which can be allowed even if MSI/MSI-X is
>     enabled, as device should consider INTx disabled anyway in that case
> 
> Fixes: 5e29500eba2a ("xen-pciback: Allow setting PCI_MSIX_FLAGS_MASKALL too")
> Signed-off-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>

Acked-by: Juergen Gross <jgross@suse.com>


Juergen


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