Re: [XEN PATCH v12 4/7] x86/domctl: Add hypercall to set the access of x86 gsi

[Jan Beulich <jbeulich@xxxxxxxx>]

On 08.07.2024 13:41, Jiqian Chen wrote:
> Some type of domains don't have PIRQs, like PVH, it doesn't do
> PHYSDEVOP_map_pirq for each gsi. When passthrough a device
> to guest base on PVH dom0, callstack
> pci_add_dm_done->XEN_DOMCTL_irq_permission will fail at function
> domain_pirq_to_irq, because PVH has no mapping of gsi, pirq and
> irq on Xen side.
> What's more, current hypercall XEN_DOMCTL_irq_permission requires
> passing in pirq to set the access of irq, it is not suitable for
> dom0 that doesn't have PIRQs.
> 
> So, add a new hypercall XEN_DOMCTL_gsi_permission to grant/deny
> the permission of irq(translate from x86 gsi) to dumU when dom0
> has no PIRQs.
> 
> Signed-off-by: Jiqian Chen <Jiqian.Chen@xxxxxxx>
> Signed-off-by: Huang Rui <ray.huang@xxxxxxx>
> Signed-off-by: Jiqian Chen <Jiqian.Chen@xxxxxxx>
> ---
> CC: Daniel P . Smith <dpsmith@xxxxxxxxxxxxxxxxxxxx>
> Remaining comment @Daniel P . Smith:
> +        ret = -EPERM;
> +        if ( !irq_access_permitted(currd, irq) ||
> +             xsm_irq_permission(XSM_HOOK, d, irq, access_flag) )
> +            goto gsi_permission_out;
> Is it okay to issue the XSM check using the translated value, 
> not the one that was originally passed into the hypercall?

As long as the answer to this is going to be "Yes":
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

Daniel, awaiting your input.

Jan