Re: Linux 6.12-rc2: xen-privcmd cannot be loaded in domU anymore

["Chen, Jiqian" <Jiqian.Chen@xxxxxxx>]

On 2024/10/9 08:36, Marek Marczykowski-Górecki wrote:
> Hi,
> 
> It looks like xen-privcmd now depends on xen-pciback, and the latter
> (expectedly) fails to load in domU with -ENODEV. But that prevents
> loading xen-privcmd too. And that's bad.
Sorry for introducing that and thank you for reporting it.

Maybe that dependency can be removed.
I used it to pass the combination of compilation(CONFIG_XEN_PRIVCMD=y && 
CONFIG_XEN_PCIDEV_BACKEND=m).
But from my patch, "IS_REACHABLE(CONFIG_XEN_PCIDEV_BACKEND)" is enough. And I 
have tested locally just now.
Juergen and Stefano, what's your opinion?

> 
> The dependency looks to be introduced by this commit:
> 
> commit 2fae6bb7be320270801b3c3b040189bd7daa8056
> Author: Jiqian Chen <Jiqian.Chen@xxxxxxx>
> Date:   Tue Sep 24 14:14:37 2024 +0800
> 
>     xen/privcmd: Add new syscall to get gsi from dev
>     
>     On PVH dom0, when passthrough a device to domU, QEMU and xl tools
>     want to use gsi number to do pirq mapping, see QEMU code
>     xen_pt_realize->xc_physdev_map_pirq, and xl code
>     pci_add_dm_done->xc_physdev_map_pirq, but in current codes, the gsi
>     number is got from file /sys/bus/pci/devices/<sbdf>/irq, that is
>     wrong, because irq is not equal with gsi, they are in different
>     spaces, so pirq mapping fails.
>     And in current linux codes, there is no method to get gsi
>     for userspace.
>     
>     For above purpose, record gsi of pcistub devices when init
>     pcistub and add a new syscall into privcmd to let userspace
>     can get gsi when they have a need.
>     
>     Signed-off-by: Jiqian Chen <Jiqian.Chen@xxxxxxx>
>     Signed-off-by: Huang Rui <ray.huang@xxxxxxx>
>     Signed-off-by: Jiqian Chen <Jiqian.Chen@xxxxxxx>
>     Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
>     Message-ID: <20240924061437.2636766-4-Jiqian.Chen@xxxxxxx>
>     Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
> 
> 

-- 
Best regards,
Jiqian Chen.