iommu/vt-d: Set the nested domain to a device

This adds the helper for setting the nested domain to a device hence
enable nested domain usage on Intel VT-d.

Link: https://lore.kernel.org/r/20231026044216.64964-7-yi.l.liu@intel.com
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Signed-off-by: Yi Liu <yi.l.liu@intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

Author: yiliu1765

drivers/iommu/intel/nested.c

@@ -12,15 +12,69 @@
 #define pr_fmt(fmt)	"DMAR: " fmt
 
 #include <linux/iommu.h>
+#include <linux/pci.h>
+#include <linux/pci-ats.h>
 
 #include "iommu.h"
+#include "pasid.h"
+
+static int intel_nested_attach_dev(struct iommu_domain *domain,
+				   struct device *dev)
+{
+	struct device_domain_info *info = dev_iommu_priv_get(dev);
+	struct dmar_domain *dmar_domain = to_dmar_domain(domain);
+	struct intel_iommu *iommu = info->iommu;
+	unsigned long flags;
+	int ret = 0;
+
+	if (info->domain)
+		device_block_translation(dev);
+
+	if (iommu->agaw < dmar_domain->s2_domain->agaw) {
+		dev_err_ratelimited(dev, "Adjusted guest address width not compatible\n");
+		return -ENODEV;
+	}
+
+	/*
+	 * Stage-1 domain cannot work alone, it is nested on a s2_domain.
+	 * The s2_domain will be used in nested translation, hence needs
+	 * to ensure the s2_domain is compatible with this IOMMU.
+	 */
+	ret = prepare_domain_attach_device(&dmar_domain->s2_domain->domain, dev);
+	if (ret) {
+		dev_err_ratelimited(dev, "s2 domain is not compatible\n");
+		return ret;
+	}
+
+	ret = domain_attach_iommu(dmar_domain, iommu);
+	if (ret) {
+		dev_err_ratelimited(dev, "Failed to attach domain to iommu\n");
+		return ret;
+	}
+
+	ret = intel_pasid_setup_nested(iommu, dev,
+				       IOMMU_NO_PASID, dmar_domain);
+	if (ret) {
+		domain_detach_iommu(dmar_domain, iommu);
+		dev_err_ratelimited(dev, "Failed to setup pasid entry\n");
+		return ret;
+	}
+
+	info->domain = dmar_domain;
+	spin_lock_irqsave(&dmar_domain->lock, flags);
+	list_add(&info->link, &dmar_domain->devices);
+	spin_unlock_irqrestore(&dmar_domain->lock, flags);
+
+	return 0;
+}
 
 static void intel_nested_domain_free(struct iommu_domain *domain)
 {
 	kfree(to_dmar_domain(domain));
 }
 
 static const struct iommu_domain_ops intel_nested_domain_ops = {
+	.attach_dev		= intel_nested_attach_dev,
 	.free			= intel_nested_domain_free,
 };