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Subject: Re: [PATCH v13 03/15] iommu/arm-smmu-v3: Maintain a SID->device
 structure
To:     Keqian Zhu <zhukeqian1@huawei.com>, eric.auger.pro@gmail.com,
        iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org, kvmarm@lists.cs.columbia.edu, will@kernel.org,
        joro@8bytes.org, maz@kernel.org, robin.murphy@arm.com,
        alex.williamson@redhat.com
Cc:     jean-philippe@linaro.org, jacob.jun.pan@linux.intel.com,
        nicoleotsuka@gmail.com, vivek.gautam@arm.com, yi.l.liu@intel.com,
        zhangfei.gao@linaro.org
References: <20201118112151.25412-1-eric.auger@redhat.com>
 <20201118112151.25412-4-eric.auger@redhat.com>
 <a5cc1635-b69b-50a6-404a-5bf667296669@huawei.com>
From:   Auger Eric <eric.auger@redhat.com>
Message-ID: <c457b450-8755-308e-7c7a-abe23b33d0d6@redhat.com>
Date:   Mon, 1 Feb 2021 18:19:52 +0100
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Hi Keqian,

On 2/1/21 1:26 PM, Keqian Zhu wrote:
> Hi Eric,
> 
> On 2020/11/18 19:21, Eric Auger wrote:
>> From: Jean-Philippe Brucker <jean-philippe@linaro.org>
>>
>> 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 <jean-philippe@linaro.org>
> [...]
> 
>>  }
>>  
>> +static int arm_smmu_insert_master(struct arm_smmu_device *smmu,
>> +				  struct arm_smmu_master *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 = dev_iommu_fwspec_get(master->dev);
>> +
>> +	master->streams = kcalloc(fwspec->num_ids,
>> +				  sizeof(struct arm_smmu_stream), GFP_KERNEL);
>> +	if (!master->streams)
>> +		return -ENOMEM;
>> +	master->num_streams = fwspec->num_ids;
> This is not roll-backed when fail.
> 
>> +
>> +	mutex_lock(&smmu->streams_mutex);
>> +	for (i = 0; i < fwspec->num_ids && !ret; i++) {
> Check ret at here, makes it hard to decide the start index of rollback.
> 
> If we fail at here, then start index is (i-2).
> If we fail in the loop, then start index is (i-1).
> 
>> +		u32 sid = fwspec->ids[i];
>> +
>> +		new_stream = &master->streams[i];
>> +		new_stream->id = sid;
>> +		new_stream->master = master;
>> +
>> +		/*
>> +		 * Check the SIDs are in range of the SMMU and our stream table
>> +		 */
>> +		if (!arm_smmu_sid_in_range(smmu, sid)) {
>> +			ret = -ERANGE;
>> +			break;
>> +		}
>> +
>> +		/* Ensure l2 strtab is initialised */
>> +		if (smmu->features & ARM_SMMU_FEAT_2_LVL_STRTAB) {
>> +			ret = arm_smmu_init_l2_strtab(smmu, sid);
>> +			if (ret)
>> +				break;
>> +		}
>> +
>> +		/* Insert into SID tree */
>> +		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);
>> +		}
>> +	}
>> +
>> +	if (ret) {
>> +		for (; i > 0; i--)
> should be (i >= 0)?
> And the start index seems not correct.
> 
>> +			rb_erase(&master->streams[i].node, &smmu->streams);
>> +		kfree(master->streams);
>> +	}
>> +	mutex_unlock(&smmu->streams_mutex);
>> +
>> +	return ret;
>> +}
>> +
>> +static void arm_smmu_remove_master(struct arm_smmu_master *master)
>> +{
>> +	int i;
>> +	struct arm_smmu_device *smmu = master->smmu;
>> +	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(master->dev);
>> +
>> +	if (!smmu || !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 struct iommu_device *arm_smmu_probe_device(struct device *dev)
>>  {
>> -	int i, ret;
>> +	int ret;
>>  	struct arm_smmu_device *smmu;
>>  	struct arm_smmu_master *master;
>>  	struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
>> @@ -2331,27 +2447,12 @@ static struct iommu_device *arm_smmu_probe_device(struct device *dev)
>>  
>>  	master->dev = dev;
>>  	master->smmu = smmu;
>> -	master->sids = fwspec->ids;
>> -	master->num_sids = fwspec->num_ids;
>>  	INIT_LIST_HEAD(&master->bonds);
>>  	dev_iommu_priv_set(dev, master);
>>  
>> -	/* Check the SIDs are in range of the SMMU and our stream table */
>> -	for (i = 0; i < master->num_sids; i++) {
>> -		u32 sid = master->sids[i];
>> -
>> -		if (!arm_smmu_sid_in_range(smmu, sid)) {
>> -			ret = -ERANGE;
>> -			goto err_free_master;
>> -		}
>> -
>> -		/* Ensure l2 strtab is initialised */
>> -		if (smmu->features & ARM_SMMU_FEAT_2_LVL_STRTAB) {
>> -			ret = arm_smmu_init_l2_strtab(smmu, sid);
>> -			if (ret)
>> -				goto err_free_master;
>> -		}
>> -	}
>> +	ret = arm_smmu_insert_master(smmu, master);
>> +	if (ret)
>> +		goto err_free_master;
>>  
>>  	master->ssid_bits = min(smmu->ssid_bits, fwspec->num_pasid_bits);
>>  
>> @@ -2389,6 +2490,7 @@ static void arm_smmu_release_device(struct device *dev)
>>  	WARN_ON(arm_smmu_master_sva_enabled(master));
>>  	arm_smmu_detach_dev(master);
>>  	arm_smmu_disable_pasid(master);
>> +	arm_smmu_remove_master(master);
>>  	kfree(master);
> 
> Thanks,
> Keqian
> 
Thank you for the review. Jean will address this issues in his own
series and on my end I will rebase on this latter.

Best Regards

Eric