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iommu/apple-dart-apif: park a released device off its domain, so re-added devices don't freeze the machine #841

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Merged
DjDeveloperr merged 1 commit into from
Nov 9, 2026
Merged

iommu/apple-dart-apif: park a released device off its domain, so re-added devices don't freeze the machine #841

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61 changes: 61 additions & 0 deletions drivers/iommu/apple-dart-apif.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1548,6 +1548,66 @@ apple_dart_apif_domain_alloc_paging(struct device *dev)
return &dom->domain;
}

/*
* The core attaches this before release_device(), so a released device no
* longer uses the domain that is about to be freed. Its SIDs leave that
* domain disabled, with the domain's mappings undone, as an attach unwind
* does. Without it the SIDs stayed enabled on the freed domain's tables, and
* the next attach of the same SIDs met that stale state. Retained SIDs keep
* their current handling.
*/
static int apple_dart_apif_release_attach(struct iommu_domain *domain,
struct device *dev,
struct iommu_domain *old)
{
struct apple_dart_apif_master *master = dev_iommu_priv_get(dev);
struct apple_dart_apif_domain *prior;
unsigned long flags;
unsigned int sid;

if (!master || !old || old->owner != &apple_dart_apif_ops ||
old->ops != apple_dart_apif_ops.default_domain_ops)
return 0;
prior = to_apif_domain(old);
mutex_lock(&prior->lock);
write_lock_irqsave(&prior->streams_lock, flags);
for (unsigned int i = 0; i < master->num_darts; i++) {
struct apple_dart_apif *dart = master->streams[i].dart;
struct apif_stream_map *before = apif_find_stream(prior, dart);

if (!before)
continue;
spin_lock(&dart->batch_lock);
for_each_set_bit(sid, master->streams[i].sids,
dart->num_streams) {
if (dart->retained[sid] || !test_bit(sid, before->sids))
continue;
dart->batch->count = 1;
dart->batch->op[0] = (struct apif_op){
.op = APIF_DART_DISABLE,
.arg = { sid },
};
if (apif_ring(dart))
dev_err(dart->dev,
"failed to disable SID %u at release\n",
sid);
apif_undo_replay(prior, before, sid, U64_MAX);
clear_bit(sid, before->sids);
}
spin_unlock(&dart->batch_lock);
}
write_unlock_irqrestore(&prior->streams_lock, flags);
mutex_unlock(&prior->lock);
return 0;
}

static struct iommu_domain apple_dart_apif_release_domain = {
.type = IOMMU_DOMAIN_BLOCKED,
.ops = &(const struct iommu_domain_ops){
.attach_dev = apple_dart_apif_release_attach,
},
};

static struct iommu_device *apple_dart_apif_probe_device(struct device *dev)
{
struct apple_dart_apif_master *master = dev_iommu_priv_get(dev);
Expand Down Expand Up @@ -1808,6 +1868,7 @@ static const struct iommu_ops apple_dart_apif_ops = {
.domain_alloc_paging = apple_dart_apif_domain_alloc_paging,
.probe_device = apple_dart_apif_probe_device,
.release_device = apple_dart_apif_release_device,
.release_domain = &apple_dart_apif_release_domain,
.device_group = apple_dart_apif_device_group,
.of_xlate = apple_dart_apif_of_xlate,
.owner = THIS_MODULE,
Expand Down
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