Re: [PATCH v3 03/23] xen/arm: smmuv3: Alloc io_domain for each device

[Julien Grall <julien@xxxxxxx>]

Hi Milan,

On 31/03/2026 10:52, Milan Djokic wrote:
> From: Rahul Singh <rahul.singh@xxxxxxx>
>
> In current implementation io_domain is allocated once for each xen
> domain as Stage2 translation is common for all devices in same xen
> domain.
>
> Nested stage supports S1 and S2 configuration at the same time. Stage1
> translation will be different for each device as linux kernel will
> allocate page-table for each device.
>
> Alloc io_domain for each device so that each device can have different
> Stage-1 and Stage-2 configuration structure.
>
> Signed-off-by: Rahul Singh <rahul.singh@xxxxxxx>
> Signed-off-by: Milan Djokic <milan_djokic@xxxxxxxx>
> ---
>   xen/drivers/passthrough/arm/smmu-v3.c | 13 +++++++++++--
>   1 file changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/xen/drivers/passthrough/arm/smmu-v3.c 
> b/xen/drivers/passthrough/arm/smmu-v3.c
> index f9c6837919..19e55b6c9b 100644
> --- a/xen/drivers/passthrough/arm/smmu-v3.c
> +++ b/xen/drivers/passthrough/arm/smmu-v3.c
> @@ -2809,11 +2809,13 @@ static struct arm_smmu_device 
> *arm_smmu_get_by_dev(const struct device *dev)
>   static struct iommu_domain *arm_smmu_get_domain(struct domain *d,
>                                 struct device *dev)
>   {
> +       unsigned long flags;
In Xen, we are trying to limit the scope of local variables. AFAICT, 
this is only used within the loop below. So this can be defined later. 
Same ...
>         struct iommu_domain *io_domain;
>         struct arm_smmu_domain *smmu_domain;
>         struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
>         struct arm_smmu_xen_domain *xen_domain = dom_iommu(d)->arch.priv;
>         struct arm_smmu_device *smmu = arm_smmu_get_by_dev(fwspec->iommu_dev);
> +       struct arm_smmu_master *master;
... here. Also, AFAICT, ``master`` is not meant ot be modified. So 
shouldn't this be 'const'?
Cheers,

--
Julien Grall