iommu/vt-d: Identify domains using first level page table

 */

#define DOMAIN_FLAG_LOSE_CHILDREN		BIT(1)

/*

 * When VT-d works in the scalable mode, it allows DMA translation to

 * happen through either first level or second level page table. This

 * bit marks that the DMA translation for the domain goes through the

 * first level page table, otherwise, it goes through the second level.

 */

#define DOMAIN_FLAG_USE_FIRST_LEVEL		BIT(2)

#define for_each_domain_iommu(idx, domain)			\

	for (idx = 0; idx < g_num_of_iommus; idx++)		\

		if (domain->iommu_refcnt[idx])

#endif

}

/*

 * Check and return whether first level is used by default for

 * DMA translation. Currently, we make it off by setting

 * first_level_support = 0, and will change it to -1 after all

 * map/unmap paths support first level page table.

 */

static bool first_level_by_default(void)

{

	struct dmar_drhd_unit *drhd;

	struct intel_iommu *iommu;

	static int first_level_support = 0;

	if (likely(first_level_support != -1))

		return first_level_support;

	first_level_support = 1;

	rcu_read_lock();

	for_each_active_iommu(iommu, drhd) {

		if (!sm_supported(iommu) || !ecap_flts(iommu->ecap)) {

			first_level_support = 0;

			break;

		}

	}

	rcu_read_unlock();

	return first_level_support;

}

static struct dmar_domain *alloc_domain(int flags)

{

	struct dmar_domain *domain;

	memset(domain, 0, sizeof(*domain));

	domain->nid = NUMA_NO_NODE;

	domain->flags = flags;

	if (first_level_by_default())

		domain->flags |= DOMAIN_FLAG_USE_FIRST_LEVEL;

	domain->has_iotlb_device = false;

	INIT_LIST_HEAD(&domain->devices);