From: Lu Baolu baolu.lu@linux.intel.com
[ Upstream commit 1a75cc710b956010137b4fe1d1fa3282bfd8f86c ]
Use a red-black tree(rbtree) to track devices probed by the driver's probe_device callback. These devices need to be looked up quickly by a source ID when the hardware reports a fault, either recoverable or unrecoverable.
Fault reporting paths are critical. Searching a list in this scenario is inefficient, with an algorithm complexity of O(n). An rbtree is a self-balancing binary search tree, offering an average search time complexity of O(log(n)). This significant performance improvement makes rbtrees a better choice.
Furthermore, rbtrees are implemented on a per-iommu basis, eliminating the need for global searches and further enhancing efficiency in critical fault paths. The rbtree is protected by a spin lock with interrupts disabled to ensure thread-safe access even within interrupt contexts.
Co-developed-by: Huang Jiaqing jiaqing.huang@intel.com Signed-off-by: Huang Jiaqing jiaqing.huang@intel.com Signed-off-by: Lu Baolu baolu.lu@linux.intel.com Reviewed-by: Jason Gunthorpe jgg@nvidia.com Link: https://lore.kernel.org/r/20240220065939.121116-2-baolu.lu@linux.intel.com Signed-off-by: Joerg Roedel jroedel@suse.de Stable-dep-of: 80a9b50c0b9e ("iommu/vt-d: Improve ITE fault handling if target device isn't present") Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/iommu/intel/dmar.c | 3 +- drivers/iommu/intel/iommu.c | 88 ++++++++++++++++++++++++++++++++++++- drivers/iommu/intel/iommu.h | 8 ++++ 3 files changed, 96 insertions(+), 3 deletions(-)
diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c index 23cb80d62a9ab..f9b63c2875f71 100644 --- a/drivers/iommu/intel/dmar.c +++ b/drivers/iommu/intel/dmar.c @@ -1095,7 +1095,8 @@ static int alloc_iommu(struct dmar_drhd_unit *drhd) iommu->agaw = agaw; iommu->msagaw = msagaw; iommu->segment = drhd->segment; - + iommu->device_rbtree = RB_ROOT; + spin_lock_init(&iommu->device_rbtree_lock); iommu->node = NUMA_NO_NODE;
ver = readl(iommu->reg + DMAR_VER_REG); diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c index 11652e0bcab3a..9e07e4425ff65 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -97,6 +97,81 @@ static phys_addr_t root_entry_uctp(struct root_entry *re) return re->hi & VTD_PAGE_MASK; }
+static int device_rid_cmp_key(const void *key, const struct rb_node *node) +{ + struct device_domain_info *info = + rb_entry(node, struct device_domain_info, node); + const u16 *rid_lhs = key; + + if (*rid_lhs < PCI_DEVID(info->bus, info->devfn)) + return -1; + + if (*rid_lhs > PCI_DEVID(info->bus, info->devfn)) + return 1; + + return 0; +} + +static int device_rid_cmp(struct rb_node *lhs, const struct rb_node *rhs) +{ + struct device_domain_info *info = + rb_entry(lhs, struct device_domain_info, node); + u16 key = PCI_DEVID(info->bus, info->devfn); + + return device_rid_cmp_key(&key, rhs); +} + +/* + * Looks up an IOMMU-probed device using its source ID. + * + * Returns the pointer to the device if there is a match. Otherwise, + * returns NULL. + * + * Note that this helper doesn't guarantee that the device won't be + * released by the iommu subsystem after being returned. The caller + * should use its own synchronization mechanism to avoid the device + * being released during its use if its possibly the case. + */ +struct device *device_rbtree_find(struct intel_iommu *iommu, u16 rid) +{ + struct device_domain_info *info = NULL; + struct rb_node *node; + unsigned long flags; + + spin_lock_irqsave(&iommu->device_rbtree_lock, flags); + node = rb_find(&rid, &iommu->device_rbtree, device_rid_cmp_key); + if (node) + info = rb_entry(node, struct device_domain_info, node); + spin_unlock_irqrestore(&iommu->device_rbtree_lock, flags); + + return info ? info->dev : NULL; +} + +static int device_rbtree_insert(struct intel_iommu *iommu, + struct device_domain_info *info) +{ + struct rb_node *curr; + unsigned long flags; + + spin_lock_irqsave(&iommu->device_rbtree_lock, flags); + curr = rb_find_add(&info->node, &iommu->device_rbtree, device_rid_cmp); + spin_unlock_irqrestore(&iommu->device_rbtree_lock, flags); + if (WARN_ON(curr)) + return -EEXIST; + + return 0; +} + +static void device_rbtree_remove(struct device_domain_info *info) +{ + struct intel_iommu *iommu = info->iommu; + unsigned long flags; + + spin_lock_irqsave(&iommu->device_rbtree_lock, flags); + rb_erase(&info->node, &iommu->device_rbtree); + spin_unlock_irqrestore(&iommu->device_rbtree_lock, flags); +} + /* * This domain is a statically identity mapping domain. * 1. This domain creats a static 1:1 mapping to all usable memory. @@ -4330,25 +4405,34 @@ static struct iommu_device *intel_iommu_probe_device(struct device *dev) }
dev_iommu_priv_set(dev, info); + ret = device_rbtree_insert(iommu, info); + if (ret) + goto free;
if (sm_supported(iommu) && !dev_is_real_dma_subdevice(dev)) { ret = intel_pasid_alloc_table(dev); if (ret) { dev_err(dev, "PASID table allocation failed\n"); - kfree(info); - return ERR_PTR(ret); + goto clear_rbtree; } }
intel_iommu_debugfs_create_dev(info);
return &iommu->iommu; +clear_rbtree: + device_rbtree_remove(info); +free: + kfree(info); + + return ERR_PTR(ret); }
static void intel_iommu_release_device(struct device *dev) { struct device_domain_info *info = dev_iommu_priv_get(dev);
+ device_rbtree_remove(info); dmar_remove_one_dev_info(dev); intel_pasid_free_table(dev); intel_iommu_debugfs_remove_dev(info); diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h index 4145c04cb1c68..df00240ebe90b 100644 --- a/drivers/iommu/intel/iommu.h +++ b/drivers/iommu/intel/iommu.h @@ -722,6 +722,11 @@ struct intel_iommu { struct q_inval *qi; /* Queued invalidation info */ u32 iommu_state[MAX_SR_DMAR_REGS]; /* Store iommu states between suspend and resume.*/
+ /* rb tree for all probed devices */ + struct rb_root device_rbtree; + /* protect the device_rbtree */ + spinlock_t device_rbtree_lock; + #ifdef CONFIG_IRQ_REMAP struct ir_table *ir_table; /* Interrupt remapping info */ struct irq_domain *ir_domain; @@ -755,6 +760,8 @@ struct device_domain_info { struct intel_iommu *iommu; /* IOMMU used by this device */ struct dmar_domain *domain; /* pointer to domain */ struct pasid_table *pasid_table; /* pasid table */ + /* device tracking node(lookup by PCI RID) */ + struct rb_node node; #ifdef CONFIG_INTEL_IOMMU_DEBUGFS struct dentry *debugfs_dentry; /* pointer to device directory dentry */ #endif @@ -1081,6 +1088,7 @@ void free_pgtable_page(void *vaddr); void iommu_flush_write_buffer(struct intel_iommu *iommu); 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);
#ifdef CONFIG_INTEL_IOMMU_SVM void intel_svm_check(struct intel_iommu *iommu);