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iommu/vt-d: Get rid of domain->iommu_lock
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When this lock is held the device_domain_lock is also
required to make sure the device_domain_info does not vanish
while in use. So this lock can be removed as it gives no
additional protection.

Signed-off-by: Joerg Roedel <[email protected]>
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@joergroedel
joergroedel committed Aug 12, 2015
1 parent de7e888 commit 55d9404
Showing 1 changed file with 49 additions and 38 deletions.
87 changes: 49 additions & 38 deletions drivers/iommu/intel-iommu.c
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Original file line number Diff line number Diff line change
Expand Up @@ -406,7 +406,6 @@ struct dmar_domain {
int iommu_superpage;/* Level of superpages supported:
0 == 4KiB (no superpages), 1 == 2MiB,
2 == 1GiB, 3 == 512GiB, 4 == 1TiB */
spinlock_t iommu_lock; /* protect iommu set in domain */
u64 max_addr; /* maximum mapped address */

struct iommu_domain domain; /* generic domain data structure for
Expand Down Expand Up @@ -476,6 +475,8 @@ static void dmar_remove_one_dev_info(struct dmar_domain *domain,
struct device *dev);
static void domain_context_clear(struct intel_iommu *iommu,
struct device *dev);
static void __dmar_remove_one_dev_info(struct dmar_domain *domain,
struct device *dev);
static int domain_detach_iommu(struct dmar_domain *domain,
struct intel_iommu *iommu);

Expand Down Expand Up @@ -1404,24 +1405,23 @@ iommu_support_dev_iotlb (struct dmar_domain *domain, struct intel_iommu *iommu,
u8 bus, u8 devfn)
{
bool found = false;
unsigned long flags;
struct device_domain_info *info;
struct pci_dev *pdev;

assert_spin_locked(&device_domain_lock);

if (!ecap_dev_iotlb_support(iommu->ecap))
return NULL;

if (!iommu->qi)
return NULL;

spin_lock_irqsave(&device_domain_lock, flags);
list_for_each_entry(info, &domain->devices, link)
if (info->iommu == iommu && info->bus == bus &&
info->devfn == devfn) {
found = true;
break;
}
spin_unlock_irqrestore(&device_domain_lock, flags);

if (!found || !info->dev || !dev_is_pci(info->dev))
return NULL;
Expand Down Expand Up @@ -1616,10 +1616,12 @@ static int iommu_init_domains(struct intel_iommu *iommu)
static void disable_dmar_iommu(struct intel_iommu *iommu)
{
struct device_domain_info *info, *tmp;
unsigned long flags;

if (!iommu->domains || !iommu->domain_ids)
return;

spin_lock_irqsave(&device_domain_lock, flags);
list_for_each_entry_safe(info, tmp, &device_domain_list, global) {
struct dmar_domain *domain;

Expand All @@ -1636,6 +1638,7 @@ static void disable_dmar_iommu(struct intel_iommu *iommu)
if (!domain_type_is_vm_or_si(domain))
domain_exit(domain);
}
spin_unlock_irqrestore(&device_domain_lock, flags);

if (iommu->gcmd & DMA_GCMD_TE)
iommu_disable_translation(iommu);
Expand Down Expand Up @@ -1672,7 +1675,6 @@ static struct dmar_domain *alloc_domain(int flags)
memset(domain, 0, sizeof(*domain));
domain->nid = -1;
domain->flags = flags;
spin_lock_init(&domain->iommu_lock);
INIT_LIST_HEAD(&domain->devices);

return domain;
Expand All @@ -1683,13 +1685,11 @@ static int domain_attach_iommu(struct dmar_domain *domain,
struct intel_iommu *iommu)
{
unsigned long ndomains;
unsigned long flags;
int ret, num;
int num;

assert_spin_locked(&device_domain_lock);
assert_spin_locked(&iommu->lock);

spin_lock_irqsave(&domain->iommu_lock, flags);

domain->iommu_refcnt[iommu->seq_id] += 1;
domain->iommu_count += 1;
if (domain->iommu_refcnt[iommu->seq_id] == 1) {
Expand All @@ -1700,8 +1700,7 @@ static int domain_attach_iommu(struct dmar_domain *domain,
pr_err("%s: No free domain ids\n", iommu->name);
domain->iommu_refcnt[iommu->seq_id] -= 1;
domain->iommu_count -= 1;
ret = -ENOSPC;
goto out_unlock;
return -ENOSPC;
}

set_bit(num, iommu->domain_ids);
Expand All @@ -1713,22 +1712,17 @@ static int domain_attach_iommu(struct dmar_domain *domain,
domain_update_iommu_cap(domain);
}

ret = 0;
out_unlock:
spin_unlock_irqrestore(&domain->iommu_lock, flags);

return ret;
return 0;
}

static int domain_detach_iommu(struct dmar_domain *domain,
struct intel_iommu *iommu)
{
int num, count = INT_MAX;
unsigned long flags;

assert_spin_locked(&device_domain_lock);
assert_spin_locked(&iommu->lock);

spin_lock_irqsave(&domain->iommu_lock, flags);
domain->iommu_refcnt[iommu->seq_id] -= 1;
count = --domain->iommu_count;
if (domain->iommu_refcnt[iommu->seq_id] == 0) {
Expand All @@ -1739,7 +1733,6 @@ static int domain_detach_iommu(struct dmar_domain *domain,
domain_update_iommu_cap(domain);
domain->iommu_did[iommu->seq_id] = 0;
}
spin_unlock_irqrestore(&domain->iommu_lock, flags);

return count;
}
Expand Down Expand Up @@ -1894,7 +1887,7 @@ static int domain_context_mapping_one(struct dmar_domain *domain,
struct context_entry *context;
unsigned long flags;
struct dma_pte *pgd;
int agaw;
int ret, agaw;

WARN_ON(did == 0);

Expand All @@ -1906,16 +1899,17 @@ static int domain_context_mapping_one(struct dmar_domain *domain,

BUG_ON(!domain->pgd);

spin_lock_irqsave(&iommu->lock, flags);
spin_lock_irqsave(&device_domain_lock, flags);
spin_lock(&iommu->lock);

ret = -ENOMEM;
context = iommu_context_addr(iommu, bus, devfn, 1);
spin_unlock_irqrestore(&iommu->lock, flags);
if (!context)
return -ENOMEM;
spin_lock_irqsave(&iommu->lock, flags);
if (context_present(context)) {
spin_unlock_irqrestore(&iommu->lock, flags);
return 0;
}
goto out_unlock;

ret = 0;
if (context_present(context))
goto out_unlock;

pgd = domain->pgd;

Expand All @@ -1928,11 +1922,10 @@ static int domain_context_mapping_one(struct dmar_domain *domain,
*/
if (translation != CONTEXT_TT_PASS_THROUGH) {
for (agaw = domain->agaw; agaw != iommu->agaw; agaw--) {
ret = -ENOMEM;
pgd = phys_to_virt(dma_pte_addr(pgd));
if (!dma_pte_present(pgd)) {
spin_unlock_irqrestore(&iommu->lock, flags);
return -ENOMEM;
}
if (!dma_pte_present(pgd))
goto out_unlock;
}

info = iommu_support_dev_iotlb(domain, iommu, bus, devfn);
Expand Down Expand Up @@ -1971,7 +1964,12 @@ static int domain_context_mapping_one(struct dmar_domain *domain,
iommu_flush_write_buffer(iommu);
}
iommu_enable_dev_iotlb(info);
spin_unlock_irqrestore(&iommu->lock, flags);

ret = 0;

out_unlock:
spin_unlock(&iommu->lock);
spin_unlock_irqrestore(&device_domain_lock, flags);

return 0;
}
Expand Down Expand Up @@ -2214,9 +2212,12 @@ static inline void unlink_domain_info(struct device_domain_info *info)
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(domain, info->dev);
__dmar_remove_one_dev_info(domain, info->dev);
spin_unlock_irqrestore(&device_domain_lock, flags);
}

/*
Expand Down Expand Up @@ -4539,14 +4540,16 @@ static void domain_context_clear(struct intel_iommu *iommu, struct device *dev)
pci_for_each_dma_alias(to_pci_dev(dev), &domain_context_clear_one_cb, iommu);
}

static void dmar_remove_one_dev_info(struct dmar_domain *domain,
struct device *dev)
static void __dmar_remove_one_dev_info(struct dmar_domain *domain,
struct device *dev)
{
struct device_domain_info *info;
struct intel_iommu *iommu;
unsigned long flags;
u8 bus, devfn;

assert_spin_locked(&device_domain_lock);

iommu = device_to_iommu(dev, &bus, &devfn);
if (!iommu)
return;
Expand All @@ -4556,9 +4559,7 @@ static void dmar_remove_one_dev_info(struct dmar_domain *domain,
if (WARN_ON(!info))
return;

spin_lock_irqsave(&device_domain_lock, flags);
unlink_domain_info(info);
spin_unlock_irqrestore(&device_domain_lock, flags);

iommu_disable_dev_iotlb(info);
domain_context_clear(iommu, dev);
Expand All @@ -4569,6 +4570,16 @@ static void dmar_remove_one_dev_info(struct dmar_domain *domain,
spin_unlock_irqrestore(&iommu->lock, flags);
}

static void dmar_remove_one_dev_info(struct dmar_domain *domain,
struct device *dev)
{
unsigned long flags;

spin_lock_irqsave(&device_domain_lock, flags);
__dmar_remove_one_dev_info(domain, dev);
spin_unlock_irqrestore(&device_domain_lock, flags);
}

static int md_domain_init(struct dmar_domain *domain, int guest_width)
{
int adjust_width;
Expand Down

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