iommu/vt-d: Add cache tag assignment interface

Caching tag is a combination of tags used by the hardware to cache various
translations. Whenever a mapping in a domain is changed, the IOMMU driver
should invalidate the caches with the caching tags. The VT-d specification
describes caching tags in section 6.2.1, Tagging of Cached Translations.

Add interface to assign caching tags to an IOMMU domain when attached to a
RID or PASID, and unassign caching tags when a domain is detached from a
RID or PASID. All caching tags are listed in the per-domain tag list and
are protected by a dedicated lock.

In addition to the basic IOTLB and devTLB caching tag types, NESTING_IOTLB
and NESTING_DEVTLB tag types are also introduced. These tags are used for
caches that store translations for DMA accesses through a nested user
domain. They are affected by changes to mappings in the parent domain.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Link: https://lore.kernel.org/r/20240416080656.60968-2-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>

1 files changed, 31 insertions, 0 deletions

diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h
index 9ee326f7bf62..b7c79cc19681 100644
--- a/drivers/iommu/intel/iommu.h
+++ b/drivers/iommu/intel/iommu.h
@@ -606,6 +606,9 @@ struct dmar_domain {
 	struct list_head devices;	/* all devices' list */
 	struct list_head dev_pasids;	/* all attached pasids */
 
+	spinlock_t cache_lock;		/* Protect the cache tag list */
+	struct list_head cache_tags;	/* Cache tag list */
+
 	int		iommu_superpage;/* Level of superpages supported:
 					   0 == 4KiB (no superpages), 1 == 2MiB,
 					   2 == 1GiB, 3 == 512GiB, 4 == 1TiB */
@@ -1091,6 +1094,34 @@ struct iommu_domain *intel_nested_domain_alloc(struct iommu_domain *parent,
 					       const struct iommu_user_data *user_data);
 struct device *device_rbtree_find(struct intel_iommu *iommu, u16 rid);
 
+enum cache_tag_type {
+	CACHE_TAG_IOTLB,
+	CACHE_TAG_DEVTLB,
+	CACHE_TAG_NESTING_IOTLB,
+	CACHE_TAG_NESTING_DEVTLB,
+};
+
+struct cache_tag {
+	struct list_head node;
+	enum cache_tag_type type;
+	struct intel_iommu *iommu;
+	/*
+	 * The @dev field represents the location of the cache. For IOTLB, it
+	 * resides on the IOMMU hardware. @dev stores the device pointer to
+	 * the IOMMU hardware. For DevTLB, it locates in the PCIe endpoint.
+	 * @dev stores the device pointer to that endpoint.
+	 */
+	struct device *dev;
+	u16 domain_id;
+	ioasid_t pasid;
+	unsigned int users;
+};
+
+int cache_tag_assign_domain(struct dmar_domain *domain,
+			    struct device *dev, ioasid_t pasid);
+void cache_tag_unassign_domain(struct dmar_domain *domain,
+			       struct device *dev, ioasid_t pasid);
+
 #ifdef CONFIG_INTEL_IOMMU_SVM
 void intel_svm_check(struct intel_iommu *iommu);
 int intel_svm_enable_prq(struct intel_iommu *iommu);