iommu/vt-d: Add basic SVM PASID support

This provides basic PASID support for endpoint devices, tested with a
version of the i915 driver.

Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>

1 files changed, 104 insertions, 0 deletions

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 9995ea8..60b66d2 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -4929,6 +4929,110 @@ static void intel_iommu_remove_device(struct device *dev)
 	iommu_device_unlink(iommu->iommu_dev, dev);
 }
 
+#ifdef CONFIG_INTEL_IOMMU_SVM
+int intel_iommu_enable_pasid(struct intel_iommu *iommu, struct intel_svm_dev *sdev)
+{
+	struct device_domain_info *info;
+	struct context_entry *context;
+	struct dmar_domain *domain;
+	unsigned long flags;
+	u64 ctx_lo;
+	int ret;
+
+	domain = get_valid_domain_for_dev(sdev->dev);
+	if (!domain)
+		return -EINVAL;
+
+	spin_lock_irqsave(&device_domain_lock, flags);
+	spin_lock(&iommu->lock);
+
+	ret = -EINVAL;
+	info = sdev->dev->archdata.iommu;
+	if (!info || !info->pasid_supported)
+		goto out;
+
+	context = iommu_context_addr(iommu, info->bus, info->devfn, 0);
+	if (WARN_ON(!context))
+		goto out;
+
+	ctx_lo = context[0].lo;
+
+	sdev->did = domain->iommu_did[iommu->seq_id];
+	sdev->sid = PCI_DEVID(info->bus, info->devfn);
+
+	if (!(ctx_lo & CONTEXT_PASIDE)) {
+		context[1].hi = (u64)virt_to_phys(iommu->pasid_state_table);
+		context[1].lo = (u64)virt_to_phys(iommu->pasid_table) | ecap_pss(iommu->ecap);
+		wmb();
+		/* CONTEXT_TT_MULTI_LEVEL and CONTEXT_TT_DEV_IOTLB are both
+		 * extended to permit requests-with-PASID if the PASIDE bit
+		 * is set. which makes sense. For CONTEXT_TT_PASS_THROUGH,
+		 * however, the PASIDE bit is ignored and requests-with-PASID
+		 * are unconditionally blocked. Which makes less sense.
+		 * So convert from CONTEXT_TT_PASS_THROUGH to one of the new
+		 * "guest mode" translation types depending on whether ATS
+		 * is available or not. Annoyingly, we can't use the new
+		 * modes *unless* PASIDE is set. */
+		if ((ctx_lo & CONTEXT_TT_MASK) == (CONTEXT_TT_PASS_THROUGH << 2)) {
+			ctx_lo &= ~CONTEXT_TT_MASK;
+			if (info->ats_supported)
+				ctx_lo |= CONTEXT_TT_PT_PASID_DEV_IOTLB << 2;
+			else
+				ctx_lo |= CONTEXT_TT_PT_PASID << 2;
+		}
+		ctx_lo |= CONTEXT_PASIDE;
+		context[0].lo = ctx_lo;
+		wmb();
+		iommu->flush.flush_context(iommu, sdev->did, sdev->sid,
+					   DMA_CCMD_MASK_NOBIT,
+					   DMA_CCMD_DEVICE_INVL);
+	}
+
+	/* Enable PASID support in the device, if it wasn't already */
+	if (!info->pasid_enabled)
+		iommu_enable_dev_iotlb(info);
+
+	if (info->ats_enabled) {
+		sdev->dev_iotlb = 1;
+		sdev->qdep = info->ats_qdep;
+		if (sdev->qdep >= QI_DEV_EIOTLB_MAX_INVS)
+			sdev->qdep = 0;
+	}
+	ret = 0;
+
+ out:
+	spin_unlock(&iommu->lock);
+	spin_unlock_irqrestore(&device_domain_lock, flags);
+
+	return ret;
+}
+
+struct intel_iommu *intel_svm_device_to_iommu(struct device *dev)
+{
+	struct intel_iommu *iommu;
+	u8 bus, devfn;
+
+	if (iommu_dummy(dev)) {
+		dev_warn(dev,
+			 "No IOMMU translation for device; cannot enable SVM\n");
+		return NULL;
+	}
+
+	iommu = device_to_iommu(dev, &bus, &devfn);
+	if ((!iommu)) {
+		dev_dbg(dev, "No IOMMU for device; cannot enable SVM\n");
+		return NULL;
+	}
+
+	if (!iommu->pasid_table) {
+		dev_dbg(dev, "PASID not enabled on IOMMU; cannot enable SVM\n");
+		return NULL;
+	}
+
+	return iommu;
+}
+#endif /* CONFIG_INTEL_IOMMU_SVM */
+
 static const struct iommu_ops intel_iommu_ops = {
 	.capable	= intel_iommu_capable,
 	.domain_alloc	= intel_iommu_domain_alloc,