Re: [PATCH v7 11/23] iommu/arm-smmu-v3: Maintain a SID->device structure
On 08/05/2019 15:05, Robin Murphy wrote: > On 08/04/2019 13:18, Eric Auger wrote: >> From: Jean-Philippe Brucker >> >> When handling faults from the event or PRI queue, we need to find the >> struct device associated to a SID. Add a rb_tree to keep track of SIDs. > > Out of curiosity, have you looked at whether an xarray might now be a > more efficient option for this? I hadn't looked into it yet, but it's a welcome distraction. * Searching by SID will be more efficient with xarray (which still is a radix tree, with a better API). Rather than O(log2(n)) we walk O(log_c(n)) nodes in the worst case, with c = XA_CHUNK_SIZE = 64. We don't care about insertion/deletion time. * Memory consumption is worse than rb-tree, when the SID space is a little sparse. For PCI devices the three LSBs (function number) might not be in use, meaning that 88% of the leaf slots would be unused. And it gets worse if the system has lots of bridges, as each bus number requires its own xa slot, ie. 98% unused. It's not too bad though, and in general I think the distribution of SIDs would be good enough to justify using xarray. Plugging in more devices would increase the memory consumption fast, but creating virtual functions wouldn't. On one machine (TX2, a few discrete PCI cards) I need 16 xa slots to store 42 device IDs. That's 16 * 576 bytes = 9 kB, versus 42 * 40 bytes = 1.6 kB for the rb-tree. On another machine (x86, lots of RC integrated endpoints) I need 18 slots to store 181 device IDs, 10 kB vs. 7 kB with the rb-tree. * Using xa would make this code a lot nicer. Shame that we can't store the device pointer directly in the STE though, there is already plenty of unused space in there. Thanks, Jean ___ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
Re: [PATCH v7 11/23] iommu/arm-smmu-v3: Maintain a SID->device structure
On 08/04/2019 13:18, Eric Auger wrote:
From: Jean-Philippe Brucker
When handling faults from the event or PRI queue, we need to find the
struct device associated to a SID. Add a rb_tree to keep track of SIDs.
Out of curiosity, have you looked at whether an xarray might now be a
more efficient option for this?
Robin.
Signed-off-by: Jean-Philippe Brucker
---
drivers/iommu/arm-smmu-v3.c | 136 ++--
1 file changed, 132 insertions(+), 4 deletions(-)
diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index ff998c967a0a..21d027695181 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -588,6 +588,16 @@ struct arm_smmu_device {
/* IOMMU core code handle */
struct iommu_device iommu;
+
+ struct rb_root streams;
+ struct mutexstreams_mutex;
+
+};
+
+struct arm_smmu_stream {
+ u32 id;
+ struct arm_smmu_master_data *master;
+ struct rb_node node;
};
/* SMMU private data for each master */
@@ -597,6 +607,7 @@ struct arm_smmu_master_data {
struct arm_smmu_domain *domain;
struct list_headlist; /* domain->devices */
+ struct arm_smmu_stream *streams;
struct device *dev;
};
@@ -1243,6 +1254,32 @@ static int arm_smmu_init_l2_strtab(struct
arm_smmu_device *smmu, u32 sid)
return 0;
}
+__maybe_unused
+static struct arm_smmu_master_data *
+arm_smmu_find_master(struct arm_smmu_device *smmu, u32 sid)
+{
+ struct rb_node *node;
+ struct arm_smmu_stream *stream;
+ struct arm_smmu_master_data *master = NULL;
+
+ mutex_lock(>streams_mutex);
+ node = smmu->streams.rb_node;
+ while (node) {
+ stream = rb_entry(node, struct arm_smmu_stream, node);
+ if (stream->id < sid) {
+ node = node->rb_right;
+ } else if (stream->id > sid) {
+ node = node->rb_left;
+ } else {
+ master = stream->master;
+ break;
+ }
+ }
+ mutex_unlock(>streams_mutex);
+
+ return master;
+}
+
/* IRQ and event handlers */
static irqreturn_t arm_smmu_evtq_thread(int irq, void *dev)
{
@@ -1881,6 +1918,71 @@ static bool arm_smmu_sid_in_range(struct arm_smmu_device
*smmu, u32 sid)
return sid < limit;
}
+static int arm_smmu_insert_master(struct arm_smmu_device *smmu,
+ struct arm_smmu_master_data *master)
+{
+ int i;
+ int ret = 0;
+ struct arm_smmu_stream *new_stream, *cur_stream;
+ struct rb_node **new_node, *parent_node = NULL;
+ struct iommu_fwspec *fwspec = master->dev->iommu_fwspec;
+
+ master->streams = kcalloc(fwspec->num_ids,
+ sizeof(struct arm_smmu_stream), GFP_KERNEL);
+ if (!master->streams)
+ return -ENOMEM;
+
+ mutex_lock(>streams_mutex);
+ for (i = 0; i < fwspec->num_ids && !ret; i++) {
+ new_stream = >streams[i];
+ new_stream->id = fwspec->ids[i];
+ new_stream->master = master;
+
+ new_node = &(smmu->streams.rb_node);
+ while (*new_node) {
+ cur_stream = rb_entry(*new_node, struct arm_smmu_stream,
+ node);
+ parent_node = *new_node;
+ if (cur_stream->id > new_stream->id) {
+ new_node = &((*new_node)->rb_left);
+ } else if (cur_stream->id < new_stream->id) {
+ new_node = &((*new_node)->rb_right);
+ } else {
+ dev_warn(master->dev,
+"stream %u already in tree\n",
+cur_stream->id);
+ ret = -EINVAL;
+ break;
+ }
+ }
+
+ if (!ret) {
+ rb_link_node(_stream->node, parent_node, new_node);
+ rb_insert_color(_stream->node, >streams);
+ }
+ }
+ mutex_unlock(>streams_mutex);
+
+ return ret;
+}
+
+static void arm_smmu_remove_master(struct arm_smmu_device *smmu,
+ struct arm_smmu_master_data *master)
+{
+ int i;
+ struct iommu_fwspec *fwspec = master->dev->iommu_fwspec;
+
+ if (!master->streams)
+ return;
+
+ mutex_lock(>streams_mutex);
+ for (i = 0; i < fwspec->num_ids; i++)
+ rb_erase(>streams[i].node, >streams);
+ mutex_unlock(>streams_mutex);
+
+ kfree(master->streams);
+}
+
static struct iommu_ops arm_smmu_ops;
static
[PATCH v7 11/23] iommu/arm-smmu-v3: Maintain a SID->device structure
From: Jean-Philippe Brucker
When handling faults from the event or PRI queue, we need to find the
struct device associated to a SID. Add a rb_tree to keep track of SIDs.
Signed-off-by: Jean-Philippe Brucker
---
drivers/iommu/arm-smmu-v3.c | 136 ++--
1 file changed, 132 insertions(+), 4 deletions(-)
diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
index ff998c967a0a..21d027695181 100644
--- a/drivers/iommu/arm-smmu-v3.c
+++ b/drivers/iommu/arm-smmu-v3.c
@@ -588,6 +588,16 @@ struct arm_smmu_device {
/* IOMMU core code handle */
struct iommu_device iommu;
+
+ struct rb_root streams;
+ struct mutexstreams_mutex;
+
+};
+
+struct arm_smmu_stream {
+ u32 id;
+ struct arm_smmu_master_data *master;
+ struct rb_node node;
};
/* SMMU private data for each master */
@@ -597,6 +607,7 @@ struct arm_smmu_master_data {
struct arm_smmu_domain *domain;
struct list_headlist; /* domain->devices */
+ struct arm_smmu_stream *streams;
struct device *dev;
};
@@ -1243,6 +1254,32 @@ static int arm_smmu_init_l2_strtab(struct
arm_smmu_device *smmu, u32 sid)
return 0;
}
+__maybe_unused
+static struct arm_smmu_master_data *
+arm_smmu_find_master(struct arm_smmu_device *smmu, u32 sid)
+{
+ struct rb_node *node;
+ struct arm_smmu_stream *stream;
+ struct arm_smmu_master_data *master = NULL;
+
+ mutex_lock(>streams_mutex);
+ node = smmu->streams.rb_node;
+ while (node) {
+ stream = rb_entry(node, struct arm_smmu_stream, node);
+ if (stream->id < sid) {
+ node = node->rb_right;
+ } else if (stream->id > sid) {
+ node = node->rb_left;
+ } else {
+ master = stream->master;
+ break;
+ }
+ }
+ mutex_unlock(>streams_mutex);
+
+ return master;
+}
+
/* IRQ and event handlers */
static irqreturn_t arm_smmu_evtq_thread(int irq, void *dev)
{
@@ -1881,6 +1918,71 @@ static bool arm_smmu_sid_in_range(struct arm_smmu_device
*smmu, u32 sid)
return sid < limit;
}
+static int arm_smmu_insert_master(struct arm_smmu_device *smmu,
+ struct arm_smmu_master_data *master)
+{
+ int i;
+ int ret = 0;
+ struct arm_smmu_stream *new_stream, *cur_stream;
+ struct rb_node **new_node, *parent_node = NULL;
+ struct iommu_fwspec *fwspec = master->dev->iommu_fwspec;
+
+ master->streams = kcalloc(fwspec->num_ids,
+ sizeof(struct arm_smmu_stream), GFP_KERNEL);
+ if (!master->streams)
+ return -ENOMEM;
+
+ mutex_lock(>streams_mutex);
+ for (i = 0; i < fwspec->num_ids && !ret; i++) {
+ new_stream = >streams[i];
+ new_stream->id = fwspec->ids[i];
+ new_stream->master = master;
+
+ new_node = &(smmu->streams.rb_node);
+ while (*new_node) {
+ cur_stream = rb_entry(*new_node, struct arm_smmu_stream,
+ node);
+ parent_node = *new_node;
+ if (cur_stream->id > new_stream->id) {
+ new_node = &((*new_node)->rb_left);
+ } else if (cur_stream->id < new_stream->id) {
+ new_node = &((*new_node)->rb_right);
+ } else {
+ dev_warn(master->dev,
+"stream %u already in tree\n",
+cur_stream->id);
+ ret = -EINVAL;
+ break;
+ }
+ }
+
+ if (!ret) {
+ rb_link_node(_stream->node, parent_node, new_node);
+ rb_insert_color(_stream->node, >streams);
+ }
+ }
+ mutex_unlock(>streams_mutex);
+
+ return ret;
+}
+
+static void arm_smmu_remove_master(struct arm_smmu_device *smmu,
+ struct arm_smmu_master_data *master)
+{
+ int i;
+ struct iommu_fwspec *fwspec = master->dev->iommu_fwspec;
+
+ if (!master->streams)
+ return;
+
+ mutex_lock(>streams_mutex);
+ for (i = 0; i < fwspec->num_ids; i++)
+ rb_erase(>streams[i].node, >streams);
+ mutex_unlock(>streams_mutex);
+
+ kfree(master->streams);
+}
+
static struct iommu_ops arm_smmu_ops;
static int arm_smmu_add_device(struct device *dev)
@@ -1929,13 +2031,35 @@ static int arm_smmu_add_device(struct device *dev)
}
