Re: [PATCH v7 11/23] iommu/arm-smmu-v3: Maintain a SID->device structure

Robin Murphy
2019-05-08T14:05:54Z

On 08/04/2019 13:18, Eric Auger wrote:
> From: Jean-Philippe Brucker <jean-philippe.brucker@arm.com>
>
> 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 <jean-philippe.brucker@arm.com>
> ---
> 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 mutex streams_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_head list; /* 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(&smmu->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(&smmu->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(&smmu->streams_mutex);
> + for (i = 0; i < fwspec->num_ids && !ret; i++) {
> + new_stream = &master->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(&new_stream->node, parent_node, new_node);
> + rb_insert_color(&new_stream->node, &smmu->streams);
> + }
> + }
> + mutex_unlock(&smmu->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(&smmu->streams_mutex);
> + for (i = 0; i < fwspec->num_ids; i++)
> + rb_erase(&master->streams[i].node, &smmu->streams);
> + mutex_unlock(&smmu->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)
> }
> }
>
> + ret = iommu_device_link(&smmu->iommu, dev);
> + if (ret)
> + goto err_free_master;
> +
> + ret = arm_smmu_insert_master(smmu, master);
> + if (ret)
> + goto err_unlink;
> +
> group = iommu_group_get_for_dev(dev);
> - if (!IS_ERR(group)) {
> - iommu_group_put(group);
> - iommu_device_link(&smmu->iommu, dev);
> + if (IS_ERR(group)) {
> + ret = PTR_ERR(group);
> + goto err_remove_master;
> }
>
> - return PTR_ERR_OR_ZERO(group);
> + iommu_group_put(group);
> +
> + return 0;
> +
> +err_remove_master:
> + arm_smmu_remove_master(smmu, master);
> +
> +err_unlink:
> + iommu_device_unlink(&smmu->iommu, dev);
> +
> +err_free_master:
> + kfree(master);
> + fwspec->iommu_priv = NULL;
> +
> + return ret;
> }
>
> static void arm_smmu_remove_device(struct device *dev)
> @@ -1952,6 +2076,7 @@ static void arm_smmu_remove_device(struct device *dev)
> if (master && master->ste.assigned)
> arm_smmu_detach_dev(dev);
> iommu_group_remove_device(dev);
> + arm_smmu_remove_master(smmu, master);
> iommu_device_unlink(&smmu->iommu, dev);
> kfree(master);
> iommu_fwspec_free(dev);
> @@ -2265,6 +2390,9 @@ static int arm_smmu_init_structures(struct arm_smmu_device *smmu)
> {
> int ret;
>
> + mutex_init(&smmu->streams_mutex);
> + smmu->streams = RB_ROOT;
> +
> ret = arm_smmu_init_queues(smmu);
> if (ret)
> return ret;
>