[PATCH v2 11/11] iommu/vt-d: Use rculist for per-domain device list
From: Lu Baolu
Date: Sun Feb 13 2022 - 21:59:29 EST
Use rculist for list of devices attached by a domain. And use the RCU
lock for read/write protection. As both the global device_domain array
and per-domain device_domain list are protected by RCU lock now, there
is no need to use the spinlock anymore. Cleanup device_domain_lock.
Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
---
include/linux/intel-iommu.h | 2 +-
drivers/iommu/intel/debugfs.c | 11 +--
drivers/iommu/intel/iommu.c | 126 ++++++++++++++--------------------
3 files changed, 53 insertions(+), 86 deletions(-)
diff --git a/include/linux/intel-iommu.h b/include/linux/intel-iommu.h
index aca1c1cc04a8..286bd6f82024 100644
--- a/include/linux/intel-iommu.h
+++ b/include/linux/intel-iommu.h
@@ -480,7 +480,6 @@ enum {
#define VTD_FLAG_SVM_CAPABLE (1 << 2)
extern int intel_iommu_sm;
-extern spinlock_t device_domain_lock;
#define sm_supported(iommu) (intel_iommu_sm && ecap_smts((iommu)->ecap))
#define pasid_supported(iommu) (sm_supported(iommu) && \
@@ -609,6 +608,7 @@ struct intel_iommu {
/* PCI domain-device relationship */
struct device_domain_info {
+ struct rcu_head rcu;
struct list_head link; /* link to domain siblings */
struct list_head table; /* link to pasid table */
u32 segment; /* PCI segment number */
diff --git a/drivers/iommu/intel/debugfs.c b/drivers/iommu/intel/debugfs.c
index ed796eea4581..6a115103412a 100644
--- a/drivers/iommu/intel/debugfs.c
+++ b/drivers/iommu/intel/debugfs.c
@@ -364,15 +364,8 @@ static int show_device_domain_translation(struct device *dev, void *data)
static int domain_translation_struct_show(struct seq_file *m, void *unused)
{
- unsigned long flags;
- int ret;
-
- spin_lock_irqsave(&device_domain_lock, flags);
- ret = bus_for_each_dev(&pci_bus_type, NULL, m,
- show_device_domain_translation);
- spin_unlock_irqrestore(&device_domain_lock, flags);
-
- return ret;
+ return bus_for_each_dev(&pci_bus_type, NULL, m,
+ show_device_domain_translation);
}
DEFINE_SHOW_ATTRIBUTE(domain_translation_struct);
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index ecec923ce191..303d6d93e381 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -294,7 +294,6 @@ static LIST_HEAD(dmar_satc_units);
/* bitmap for indexing intel_iommus */
static int g_num_of_iommus;
-static void domain_remove_dev_info(struct dmar_domain *domain);
static void dmar_remove_one_dev_info(struct device *dev);
static void __dmar_remove_one_dev_info(struct device_domain_info *info);
@@ -315,7 +314,6 @@ static int iommu_skip_te_disable;
int intel_iommu_gfx_mapped;
EXPORT_SYMBOL_GPL(intel_iommu_gfx_mapped);
-DEFINE_SPINLOCK(device_domain_lock);
static DEFINE_XARRAY_ALLOC(device_domain_array);
/* Convert device source ID into the index of device_domain_array. */
@@ -597,12 +595,11 @@ static int domain_update_device_node(struct dmar_domain *domain)
struct device_domain_info *info;
int nid = NUMA_NO_NODE;
- assert_spin_locked(&device_domain_lock);
-
if (list_empty(&domain->devices))
return NUMA_NO_NODE;
- list_for_each_entry(info, &domain->devices, link) {
+ rcu_read_lock();
+ list_for_each_entry_rcu(info, &domain->devices, link) {
if (!info->dev)
continue;
@@ -616,6 +613,7 @@ static int domain_update_device_node(struct dmar_domain *domain)
if (nid != NUMA_NO_NODE)
break;
}
+ rcu_read_unlock();
return nid;
}
@@ -1436,25 +1434,26 @@ static void __iommu_flush_iotlb(struct intel_iommu *iommu, u16 did,
}
static struct device_domain_info *
-iommu_support_dev_iotlb (struct dmar_domain *domain, struct intel_iommu *iommu,
- u8 bus, u8 devfn)
+iommu_support_dev_iotlb(struct dmar_domain *domain, struct intel_iommu *iommu,
+ u8 bus, u8 devfn)
{
- struct device_domain_info *info;
-
- assert_spin_locked(&device_domain_lock);
+ struct device_domain_info *tmp, *info = NULL;
if (!iommu->qi)
return NULL;
- list_for_each_entry(info, &domain->devices, link)
- if (info->iommu == iommu && info->bus == bus &&
- info->devfn == devfn) {
- if (info->ats_supported && info->dev)
- return info;
+ rcu_read_lock();
+ list_for_each_entry_rcu(tmp, &domain->devices, link) {
+ if (tmp->iommu == iommu && tmp->bus == bus &&
+ tmp->devfn == devfn) {
+ if (tmp->ats_supported && tmp->dev)
+ info = tmp;
break;
}
+ }
+ rcu_read_unlock();
- return NULL;
+ return info;
}
static void domain_update_iotlb(struct dmar_domain *domain)
@@ -1462,13 +1461,14 @@ static void domain_update_iotlb(struct dmar_domain *domain)
struct device_domain_info *info;
bool has_iotlb_device = false;
- assert_spin_locked(&device_domain_lock);
-
- list_for_each_entry(info, &domain->devices, link)
+ rcu_read_lock();
+ list_for_each_entry_rcu(info, &domain->devices, link) {
if (info->ats_enabled) {
has_iotlb_device = true;
break;
}
+ }
+ rcu_read_unlock();
domain->has_iotlb_device = has_iotlb_device;
}
@@ -1477,8 +1477,6 @@ static void iommu_enable_dev_iotlb(struct device_domain_info *info)
{
struct pci_dev *pdev;
- assert_spin_locked(&device_domain_lock);
-
if (!info || !dev_is_pci(info->dev))
return;
@@ -1524,8 +1522,6 @@ static void iommu_disable_dev_iotlb(struct device_domain_info *info)
{
struct pci_dev *pdev;
- assert_spin_locked(&device_domain_lock);
-
if (!dev_is_pci(info->dev))
return;
@@ -1565,17 +1561,15 @@ static void __iommu_flush_dev_iotlb(struct device_domain_info *info,
static void iommu_flush_dev_iotlb(struct dmar_domain *domain,
u64 addr, unsigned mask)
{
- unsigned long flags;
struct device_domain_info *info;
if (!domain->has_iotlb_device)
return;
- spin_lock_irqsave(&device_domain_lock, flags);
- list_for_each_entry(info, &domain->devices, link)
+ rcu_read_lock();
+ list_for_each_entry_rcu(info, &domain->devices, link)
__iommu_flush_dev_iotlb(info, addr, mask);
-
- spin_unlock_irqrestore(&device_domain_lock, flags);
+ rcu_read_unlock();
}
static void iommu_flush_iotlb_psi(struct intel_iommu *iommu,
@@ -1820,7 +1814,7 @@ static struct dmar_domain *alloc_domain(unsigned int type)
if (first_level_by_default(type))
domain->flags |= DOMAIN_FLAG_USE_FIRST_LEVEL;
domain->has_iotlb_device = false;
- INIT_LIST_HEAD(&domain->devices);
+ INIT_LIST_HEAD_RCU(&domain->devices);
return domain;
}
@@ -1832,7 +1826,6 @@ static int domain_attach_iommu(struct dmar_domain *domain,
unsigned long ndomains;
int num;
- assert_spin_locked(&device_domain_lock);
assert_spin_locked(&iommu->lock);
domain->iommu_refcnt[iommu->seq_id] += 1;
@@ -1860,7 +1853,6 @@ static void domain_detach_iommu(struct dmar_domain *domain,
{
int num;
- assert_spin_locked(&device_domain_lock);
assert_spin_locked(&iommu->lock);
domain->iommu_refcnt[iommu->seq_id] -= 1;
@@ -1889,8 +1881,15 @@ static inline int guestwidth_to_adjustwidth(int gaw)
static void domain_exit(struct dmar_domain *domain)
{
- /* Remove associated devices and clear attached or cached domains */
- domain_remove_dev_info(domain);
+ struct device_domain_info *info, *tmp;
+
+ /*
+ * Remove associated devices and clear attached or cached domains.
+ * No worries about new devices insertion or removal. Hence no need
+ * for a lock here.
+ */
+ list_for_each_entry_safe(info, tmp, &domain->devices, link)
+ __dmar_remove_one_dev_info(info);
if (domain->pgd) {
LIST_HEAD(freelist);
@@ -1973,9 +1972,7 @@ static int domain_context_mapping_one(struct dmar_domain *domain,
BUG_ON(!domain->pgd);
- spin_lock_irqsave(&device_domain_lock, flags);
- spin_lock(&iommu->lock);
-
+ spin_lock_irqsave(&iommu->lock, flags);
ret = -ENOMEM;
context = iommu_context_addr(iommu, bus, devfn, 1);
if (!context)
@@ -2094,8 +2091,7 @@ static int domain_context_mapping_one(struct dmar_domain *domain,
ret = 0;
out_unlock:
- spin_unlock(&iommu->lock);
- spin_unlock_irqrestore(&device_domain_lock, flags);
+ spin_unlock_irqrestore(&iommu->lock, flags);
return ret;
}
@@ -2382,17 +2378,6 @@ static void domain_context_clear_one(struct device_domain_info *info, u8 bus, u8
__iommu_flush_dev_iotlb(info, 0, MAX_AGAW_PFN_WIDTH);
}
-static void domain_remove_dev_info(struct dmar_domain *domain)
-{
- struct device_domain_info *info, *tmp;
- unsigned long flags;
-
- spin_lock_irqsave(&device_domain_lock, flags);
- list_for_each_entry_safe(info, tmp, &domain->devices, link)
- __dmar_remove_one_dev_info(info);
- spin_unlock_irqrestore(&device_domain_lock, flags);
-}
-
static int domain_setup_first_level(struct intel_iommu *iommu,
struct dmar_domain *domain,
struct device *dev,
@@ -2444,17 +2429,14 @@ static struct dmar_domain *dmar_insert_one_dev_info(struct intel_iommu *iommu,
unsigned long flags;
int ret;
- spin_lock_irqsave(&device_domain_lock, flags);
- info->domain = domain;
- spin_lock(&iommu->lock);
+ spin_lock_irqsave(&iommu->lock, flags);
ret = domain_attach_iommu(domain, iommu);
- spin_unlock(&iommu->lock);
- if (ret) {
- spin_unlock_irqrestore(&device_domain_lock, flags);
+ spin_unlock_irqrestore(&iommu->lock, flags);
+ if (ret)
return NULL;
- }
- list_add(&info->link, &domain->devices);
- spin_unlock_irqrestore(&device_domain_lock, flags);
+
+ info->domain = domain;
+ list_add_rcu(&info->link, &domain->devices);
/* PASID table is mandatory for a PCI device in scalable mode. */
if (dev && dev_is_pci(dev) && sm_supported(iommu)) {
@@ -4182,8 +4164,6 @@ static void __dmar_remove_one_dev_info(struct device_domain_info *info)
struct intel_iommu *iommu;
unsigned long flags;
- assert_spin_locked(&device_domain_lock);
-
if (WARN_ON(!info))
return;
@@ -4191,16 +4171,19 @@ static void __dmar_remove_one_dev_info(struct device_domain_info *info)
domain = info->domain;
if (info->dev && !dev_is_real_dma_subdevice(info->dev)) {
- if (dev_is_pci(info->dev) && sm_supported(iommu))
+ if (dev_is_pci(info->dev) && sm_supported(iommu)) {
+ spin_lock_irqsave(&iommu->lock, flags);
intel_pasid_tear_down_entry(iommu, info->dev,
PASID_RID2PASID, false);
+ spin_unlock_irqrestore(&iommu->lock, flags);
+ }
iommu_disable_dev_iotlb(info);
domain_context_clear(info);
intel_pasid_free_table(info->dev);
}
- list_del(&info->link);
+ list_del_rcu(&info->link);
spin_lock_irqsave(&iommu->lock, flags);
domain_detach_iommu(domain, iommu);
@@ -4210,13 +4193,10 @@ static void __dmar_remove_one_dev_info(struct device_domain_info *info)
static void dmar_remove_one_dev_info(struct device *dev)
{
struct device_domain_info *info;
- unsigned long flags;
- spin_lock_irqsave(&device_domain_lock, flags);
info = dev_iommu_priv_get(dev);
if (info)
__dmar_remove_one_dev_info(info);
- spin_unlock_irqrestore(&device_domain_lock, flags);
}
static int md_domain_init(struct dmar_domain *domain, int guest_width)
@@ -4529,6 +4509,7 @@ static struct iommu_device *intel_iommu_probe_device(struct device *dev)
info->dev = dev;
info->iommu = iommu;
+ init_rcu_head(&info->rcu);
if (dev_is_pci(dev)) {
if (ecap_dev_iotlb_support(iommu->ecap) &&
pci_ats_supported(pdev) &&
@@ -4553,7 +4534,7 @@ static struct iommu_device *intel_iommu_probe_device(struct device *dev)
devi_idx(info->segment, info->bus, info->devfn),
info, GFP_KERNEL);
if (xa_err(curr) || WARN_ON(curr)) {
- kfree(info);
+ kfree_rcu(info, rcu);
return ERR_PTR(-ENOSPC);
}
@@ -4565,17 +4546,13 @@ static struct iommu_device *intel_iommu_probe_device(struct device *dev)
static void intel_iommu_release_device(struct device *dev)
{
struct device_domain_info *info = dev_iommu_priv_get(dev);
- unsigned long flags;
dmar_remove_one_dev_info(dev);
- spin_lock_irqsave(&device_domain_lock, flags);
dev_iommu_priv_set(dev, NULL);
xa_erase(&device_domain_array,
devi_idx(info->segment, info->bus, info->devfn));
- spin_unlock_irqrestore(&device_domain_lock, flags);
-
- kfree(info);
+ kfree_rcu(info, rcu);
set_dma_ops(dev, NULL);
}
@@ -4655,9 +4632,7 @@ int intel_iommu_enable_pasid(struct intel_iommu *iommu, struct device *dev)
if (!domain)
return -EINVAL;
- spin_lock_irqsave(&device_domain_lock, flags);
- spin_lock(&iommu->lock);
-
+ spin_lock_irqsave(&iommu->lock, flags);
ret = -EINVAL;
if (!info->pasid_supported)
goto out;
@@ -4686,8 +4661,7 @@ int intel_iommu_enable_pasid(struct intel_iommu *iommu, struct device *dev)
ret = 0;
out:
- spin_unlock(&iommu->lock);
- spin_unlock_irqrestore(&device_domain_lock, flags);
+ spin_unlock_irqrestore(&iommu->lock, flags);
return ret;
}
--
2.25.1