Re: [PATCH v3 15/21] iommu/vt-d: Add helper to allocate paging domain

Yi Liu
2024-06-28T05:38:54Z

On 2024/6/10 16:55, Lu Baolu wrote:
> The domain_alloc_user operation is currently implemented by allocating a
> paging domain using iommu_domain_alloc(). This is because it needs to fully
> initialize the domain before return. Add a helper to do this to avoid using
> iommu_domain_alloc().
>
> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
> ---
> drivers/iommu/intel/iommu.c | 87 +++++++++++++++++++++++++++++++++----
> 1 file changed, 78 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
> index 2e9811bf2a4e..ccde5f5972e4 100644
> --- a/drivers/iommu/intel/iommu.c
> +++ b/drivers/iommu/intel/iommu.c
> @@ -3633,6 +3633,79 @@ static struct iommu_domain blocking_domain = {
> }
> };
>
> +static int iommu_superpage_capability(struct intel_iommu *iommu, bool first_stage)
> +{
> + if (!intel_iommu_superpage)
> + return 0;
> +
> + if (first_stage)
> + return cap_fl1gp_support(iommu->cap) ? 2 : 1;
> +
> + return fls(cap_super_page_val(iommu->cap));
> +}
> +
> +static struct dmar_domain *paging_domain_alloc(struct device *dev, bool first_stage)
> +{
> + struct device_domain_info *info = dev_iommu_priv_get(dev);
> + struct intel_iommu *iommu = info->iommu;
> + struct dmar_domain *domain;
> + int addr_width;
> +
> + domain = kzalloc(sizeof(*domain), GFP_KERNEL);
> + if (!domain)
> + return ERR_PTR(-ENOMEM);
> +
> + INIT_LIST_HEAD(&domain->devices);
> + INIT_LIST_HEAD(&domain->dev_pasids);
> + INIT_LIST_HEAD(&domain->cache_tags);
> + spin_lock_init(&domain->lock);
> + spin_lock_init(&domain->cache_lock);
> + xa_init(&domain->iommu_array);
> +
> + domain->nid = dev_to_node(dev);
> + domain->has_iotlb_device = info->ats_enabled;
> + domain->use_first_level = first_stage;
> +
> + /* calculate the address width */
> + addr_width = agaw_to_width(iommu->agaw);
> + if (addr_width > cap_mgaw(iommu->cap))
> + addr_width = cap_mgaw(iommu->cap);
> + domain->gaw = addr_width;
> + domain->agaw = iommu->agaw;
> + domain->max_addr = __DOMAIN_MAX_ADDR(addr_width);
> +
> + /* iommu memory access coherency */
> + domain->iommu_coherency = iommu_paging_structure_coherency(iommu);
> +
> + /* pagesize bitmap */
> + domain->domain.pgsize_bitmap = SZ_4K;
> + domain->iommu_superpage = iommu_superpage_capability(iommu, first_stage);
> + domain->domain.pgsize_bitmap |= domain_super_pgsize_bitmap(domain);
> +
> + /*
> + * IOVA aperture: First-level translation restricts the input-address
> + * to a canonical address (i.e., address bits 63:N have the same value
> + * as address bit [N-1], where N is 48-bits with 4-level paging and
> + * 57-bits with 5-level paging). Hence, skip bit [N-1].
> + */
> + domain->domain.geometry.force_aperture = true;
> + domain->domain.geometry.aperture_start = 0;
> + if (first_stage)
> + domain->domain.geometry.aperture_end = __DOMAIN_MAX_ADDR(domain->gaw - 1);
> + else
> + domain->domain.geometry.aperture_end = __DOMAIN_MAX_ADDR(domain->gaw);
> +
> + /* always allocate the top pgd */
> + domain->pgd = iommu_alloc_page_node(domain->nid, GFP_KERNEL);
> + if (!domain->pgd) {
> + kfree(domain);
> + return ERR_PTR(-ENOMEM);
> + }
> + domain_flush_cache(domain, domain->pgd, PAGE_SIZE);
> +
> + return domain;
> +}
> +
> static struct iommu_domain *intel_iommu_domain_alloc(unsigned type)
> {
> struct dmar_domain *dmar_domain;
> @@ -3695,15 +3768,11 @@ intel_iommu_domain_alloc_user(struct device *dev, u32 flags,
> if (user_data || (dirty_tracking && !ssads_supported(iommu)))
> return ERR_PTR(-EOPNOTSUPP);
>
> - /*
> - * domain_alloc_user op needs to fully initialize a domain before
> - * return, so uses iommu_domain_alloc() here for simple.
> - */
> - domain = iommu_domain_alloc(dev->bus);
> - if (!domain)
> - return ERR_PTR(-ENOMEM);
> -
> - dmar_domain = to_dmar_domain(domain);
> + /* Do not use first stage for user domain translation. */
> + dmar_domain = paging_domain_alloc(dev, false);

this is not an apple-to-apple replacement yet. You need to set the type,
owner and domain->ops as well.

> + if (IS_ERR(dmar_domain))
> + return ERR_CAST(dmar_domain);
> + domain = &dmar_domain->domain;
>
> if (nested_parent) {
> dmar_domain->nested_parent = true;

--
Regards,
Yi Liu