Re: [PATCH v2 5/5] iommu/vt-d: Add nested domain support

["Liu, Jingqi" <jingqi.liu@intel.com>]

On 3/9/2023 4:22 PM, Yi Liu wrote:
> From: Lu Baolu <baolu.lu@linux.intel.com>
>
> This adds nested domain support in the Intel IOMMU driver. It allows to
> allocate and free a nested domain, set the nested domain to a device,
> and synchronize the caches when the userspace managed page tables are
> updated.
>
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
> Signed-off-by: Nicolin Chen <nicolinc@nvidia.com>
> Signed-off-by: Yi Liu <yi.l.liu@intel.com>
> ---
>   drivers/iommu/intel/Makefile |   2 +-
>   drivers/iommu/intel/iommu.c  |  38 ++++++----
>   drivers/iommu/intel/iommu.h  |  15 ++++
>   drivers/iommu/intel/nested.c | 143 +++++++++++++++++++++++++++++++++++
>   4 files changed, 182 insertions(+), 16 deletions(-)
>   create mode 100644 drivers/iommu/intel/nested.c
[...]

> +
> +struct iommu_domain *intel_nested_domain_alloc(struct iommu_domain *s2_domain,
> +					       const void *user_data)
> +{
> +	const struct iommu_hwpt_intel_vtd *vtd = user_data;
> +	struct dmar_domain *domain;
> +

Would it be better to add the following check ?

     	if (WARN_ON(!user_data))
		return NULL;

> +	domain = kzalloc(sizeof(*domain), GFP_KERNEL_ACCOUNT);
> +	if (!domain)
> +		return NULL;
> +
> +	domain->use_first_level = true;
> +	domain->s2_domain = to_dmar_domain(s2_domain);
> +	domain->s1_pgtbl = vtd->pgtbl_addr;
> +	domain->s1_cfg = *vtd;
> +	domain->domain.ops = &intel_nested_domain_ops;
> +	domain->domain.type = IOMMU_DOMAIN_NESTED;
> +	INIT_LIST_HEAD(&domain->devices);
> +	spin_lock_init(&domain->lock);
> +	xa_init(&domain->iommu_array);
> +
> +	return &domain->domain;
> +}

Thanks,

Jingqi