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

Baolu Lu
2024-06-28T08:29:21Z

On 2024/6/28 13:42, Yi Liu wrote:
> 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.

Yes. You are right. I will add below lines.

diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index d51f840715e5..c5d9c2283977 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -3732,6 +3732,9 @@ intel_iommu_domain_alloc_user(struct device *dev,
u32 flags,
if (IS_ERR(dmar_domain))
return ERR_CAST(dmar_domain);
domain = &dmar_domain->domain;
+ domain->type = IOMMU_DOMAIN_UNMANAGED;
+ domain->owner = &intel_iommu_ops;
+ domain->ops = intel_iommu_ops.default_domain_ops;

if (nested_parent) {
dmar_domain->nested_parent = true;

Best regards,
baolu