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iommu/vt-d: Replace spin_lock with mutex to protect domain ida

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The domain ID allocator is currently protected by a spin_lock. However,
ida_alloc_range can potentially block if it needs to allocate memory to
grow its internal structures.

Replace the spin_lock with a mutex which allows sleep on block. Thus,
the memory allocation flags can be updated from GFP_ATOMIC to GFP_KERNEL
to allow blocking memory allocations if necessary.

Introduce a new mutex, did_lock, specifically for protecting the domain
ida. The existing spinlock will remain for protecting other intel_iommu
fields.

Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20250430021135.2370244-3-baolu.lu@linux.intel.com
Signed-off-by: Joerg Roedel <jroedel@suse.de>
This commit is contained in:
Lu Baolu 2025-05-13 11:07:37 +08:00 committed by Joerg Roedel
parent f93b4ac592
commit 868720fe15
3 changed files with 7 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
drivers/iommu/intel/dmar.c
View File

@ -1101,6 +1101,7 @@ static int alloc_iommu(struct dmar_drhd_unit *drhd)
iommu->node = NUMA_NO_NODE;
spin_lock_init(&iommu->lock);
ida_init(&iommu->domain_ida);
mutex_init(&iommu->did_lock);
ver = readl(iommu->reg + DMAR_VER_REG);
pr_info("%s: reg_base_addr %llx ver %d:%d cap %llx ecap %llx\n",

12
drivers/iommu/intel/iommu.c
View File

@ -1345,17 +1345,16 @@ int domain_attach_iommu(struct dmar_domain *domain, struct intel_iommu *iommu)
if (!info)
return -ENOMEM;
spin_lock(&iommu->lock);
guard(mutex)(&iommu->did_lock);
curr = xa_load(&domain->iommu_array, iommu->seq_id);
if (curr) {
curr->refcnt++;
spin_unlock(&iommu->lock);
kfree(info);
return 0;
}
num = ida_alloc_range(&iommu->domain_ida, IDA_START_DID,
cap_ndoms(iommu->cap) - 1, GFP_ATOMIC);
cap_ndoms(iommu->cap) - 1, GFP_KERNEL);
if (num < 0) {
pr_err("%s: No free domain ids\n", iommu->name);
goto err_unlock;
@ -1365,19 +1364,17 @@ int domain_attach_iommu(struct dmar_domain *domain, struct intel_iommu *iommu)
info->did = num;
info->iommu = iommu;
curr = xa_cmpxchg(&domain->iommu_array, iommu->seq_id,
NULL, info, GFP_ATOMIC);
NULL, info, GFP_KERNEL);
if (curr) {
ret = xa_err(curr) ? : -EBUSY;
goto err_clear;
}
spin_unlock(&iommu->lock);
return 0;
err_clear:
ida_free(&iommu->domain_ida, info->did);
err_unlock:
spin_unlock(&iommu->lock);
kfree(info);
return ret;
}
@ -1389,7 +1386,7 @@ void domain_detach_iommu(struct dmar_domain *domain, struct intel_iommu *iommu)
if (domain->domain.type == IOMMU_DOMAIN_SVA)
return;
spin_lock(&iommu->lock);
guard(mutex)(&iommu->did_lock);
info = xa_load(&domain->iommu_array, iommu->seq_id);
if (--info->refcnt == 0) {
ida_free(&iommu->domain_ida, info->did);
@ -1397,7 +1394,6 @@ void domain_detach_iommu(struct dmar_domain *domain, struct intel_iommu *iommu)
domain->nid = NUMA_NO_NODE;
kfree(info);
}
spin_unlock(&iommu->lock);
}
static void domain_exit(struct dmar_domain *domain)

2
drivers/iommu/intel/iommu.h
View File

@ -722,6 +722,8 @@ struct intel_iommu {
unsigned char name[16]; /* Device Name */
#ifdef CONFIG_INTEL_IOMMU
/* mutex to protect domain_ida */
struct mutex did_lock;
struct ida domain_ida; /* domain id allocator */
unsigned long *copied_tables; /* bitmap of copied tables */
spinlock_t lock; /* protect context, domain ids */