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Date: Thu, 28 Sep 2023 17:02:38 +0800
From: "Liu, Jingqi" <jingqi.liu@...el.com>
To: Baolu Lu <baolu.lu@...ux.intel.com>, <iommu@...ts.linux.dev>,
Tian Kevin <kevin.tian@...el.com>,
Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
Robin Murphy <robin.murphy@....com>
CC: <linux-kernel@...r.kernel.org>
Subject: Re: [PATH v3 2/3] iommu/vt-d: debugfs: Create/remove debugfs file per
{device, pasid}
On 9/28/2023 9:58 AM, Baolu Lu wrote:
> On 9/27/23 11:15 PM, Jingqi Liu wrote:
......
>> +
>> +/* Create a debugfs directory for each device. */
>> +void intel_iommu_debugfs_create_dev(struct device *dev)
>> +{
>> + struct dentry *dev_dir;
>> +
>> + dev_dir = debugfs_lookup(dev_name(dev), intel_iommu_debug);
>> + if (!dev_dir) {
>> + dev_dir = debugfs_create_dir(dev_name(dev), intel_iommu_debug);
>> + if (IS_ERR(dev_dir))
>> + pr_info("%s: Failed to create debugfs directory.\n",
>> + dev_name(dev));
>> + } else
>> + dput(dev_dir);
>> +}
>
> Above could simply be like this:
>
> void intel_iommu_debugfs_create_dev(struct device *dev)
> {
> struct device_domain_info *info = dev_iommu_priv_get(dev);
>
> info->debugfs_entry = debugfs_create_dir(dev_name(dev),
> intel_iommu_debug);
> }
>
> Isn't it?
Thanks. Good point.
If add an "info->debugfs_dentry" to the device "info" to save the dentry
of device
debugfs directory, there's no need to lookup the dentry by debugfs_lookup().
Just simply get it from the device "info".
>
>> +
>> +void intel_iommu_debugfs_remove_dev(struct device *dev)
>> +{
>> + struct dentry *dev_dir, *sub_dir, *dentry;
>> + struct list_head *plist;
>> +
>> + dev_dir = debugfs_lookup(dev_name(dev), intel_iommu_debug);
>> + if (!dev_dir)
>> + return;
>> +
>> + list_for_each(plist, &(dev_dir->d_subdirs)) {
>> + sub_dir = list_entry(plist, struct dentry, d_child);
>> + if(sub_dir) {
>> + dentry = debugfs_lookup("domain_translation_struct",
>> + sub_dir);
>> + if (!dentry)
>> + continue;
>> +
>> + if (dentry->d_inode->i_private)
>> + kfree(dentry->d_inode->i_private);
>> +
>> + dput(dentry);
>> + }
>> + }
>> +
>> + debugfs_remove_recursive(dev_dir);
>> + dput(dev_dir);
>> +}
>
> And this could simply be like this:
>
> void intel_iommu_debugfs_remove_dev(struct device *dev)
> {
> struct device_domain_info *info = dev_iommu_priv_get(dev);
>
> debugfs_remove(info->debugfs_entry);
> }
>
Yes.
Just get the debugfs dentry of device simply for removing.
This helper should be called before the "info" is freed
in intel_iommu_release_device(). Like this:
+ intel_iommu_debugfs_remove_dev(dev);
kfree(info);
>> +
>> +/*
>> + * Create a debugfs directory per pair of {device, pasid},
>> + * then create the corresponding debugfs file in this directory
>> + * for user to dump its page table. e.g.
>> + *
>> /sys/kernel/debug/iommu/intel/0000:00:01.0/0/domain_translation_struct
>> + */
>> +void intel_iommu_debugfs_create_dev_pasid(struct iommu_domain *domain,
>> + struct device *dev, u32 pasid)
>> +{
>> + struct dentry *dev_dir, *pasid_dir;
>> + struct show_domain_info *sinfo;
>> + char dir_name[10];
>> +
>> + /*
>> + * The debugfs only dumps the page tables whose mappings are
>> created
>> + * and destroyed by the iommu_map/unmap() interfaces. Check the
>> + * mapping type of the domain before creating debugfs directory.
>> + */
>> + if (!domain || !(domain->type & __IOMMU_DOMAIN_PAGING))
>> + return;
>> +
>> + dev_dir = debugfs_lookup(dev_name(dev), intel_iommu_debug);
>> + if (!dev_dir)
>> + return;
>> +
>> + sprintf(dir_name, "%x", pasid);
>> + pasid_dir = debugfs_create_dir(dir_name, dev_dir);
>> + if (IS_ERR(pasid_dir))
>> + goto dput_out;
>> +
>> + sinfo = kzalloc(sizeof(*sinfo), GFP_KERNEL);
>> + if (!sinfo)
>> + goto dput_out;
>> +
>> + sinfo->dev = dev;
>> + sinfo->pasid = pasid;
>> + debugfs_create_file("domain_translation_struct", 0444,
>> + pasid_dir, sinfo,
>> + &domain_translation_struct_fops);
>> +dput_out:
>> + dput(dev_dir);
>> +}
>
> And here,
>
> void intel_iommu_debugfs_create_dev_pasid(struct iommu_domain *domain,
> struct device *dev, u32 pasid)
> {
> sprintf(dir_name, "%x", pasid);
> dev_pasid->debugfs_entry = debugfs_create_dir(dir_name,
> info->debugfs_entry);
>
> debugfs_create_file("domain_translation_struct", 0444,
> dev_pasid->debugfs_entry, dev_pasid,
> &domain_translation_struct_fops);
> }
>
Thanks.
You mean to add 'debugfs_entry' in below structure.
struct dev_pasid_info *dev_pasid;
This structure is also allocated per pair of {dev, pasid}.
The debugfs dentry of {dev, pasid} can be simply obtained from
'dev_pasid_info'.
So the 'dev_pasid_info' can be passed as a parameter of this helper, right ?
Like this:
void intel_iommu_debugfs_create_dev_pasid(struct iommu_domain *domain,
struct dev_pasid_info *dev_pasid) ;
>> +
>> +/*
>> + * Remove the debugfs directory and file corresponding to each pair of
>> + * {device, pasid}.
>> + */
>> +void intel_iommu_debugfs_remove_dev_pasid(struct device *dev, u32
>> pasid)
>> +{
>> + struct dentry *dev_dir, *pasid_dir, *dentry;
>> + char dir_name[10];
>> +
>> + dev_dir = debugfs_lookup(dev_name(dev), intel_iommu_debug);
>> + if (!dev_dir)
>> + return;
>> +
>> + sprintf(dir_name, "%x", pasid);
>> + pasid_dir = debugfs_lookup(dir_name, dev_dir);
>> + if (!pasid_dir)
>> + goto dput_dev;
>> +
>> + dentry = debugfs_lookup("domain_translation_struct", pasid_dir);
>> + if (!dentry)
>> + goto dput_pasid;
>> +
>> + if (dentry->d_inode->i_private)
>> + kfree(dentry->d_inode->i_private);
>> +
>> + debugfs_remove_recursive(pasid_dir);
>> +
>> + dput(dentry);
>> +dput_pasid:
>> + dput(pasid_dir);
>> +dput_dev:
>> + dput(dev_dir);
>> +}
>
> The same thing here:
>
> debugfs_remove(dev_pasid->debugfs_entry);
>
Yes.
Just get the debugfs dentry from "dev_pasid" instead of 'debugfs_lookup()'.
And this helper should be called before the "struct dev_pasid_info" is freed
in intel_iommu_remove_dev_pasid().
Like this:
+ intel_iommu_debugfs_remove_dev_pasid(dev, pasid);
kfree(dev_pasid);
>> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
>> index dd8ff358867d..af9c989035a2 100644
>> --- a/drivers/iommu/intel/iommu.c
>> +++ b/drivers/iommu/intel/iommu.c
>> @@ -2488,6 +2488,13 @@ static int dmar_domain_attach_device(struct
>> dmar_domain *domain,
>> iommu_enable_pci_caps(info);
>> + /*
>> + * Create a debugfs directory specified by RID_PASID
>> + * in the debugfs device directory.
>> + */
>> + intel_iommu_debugfs_create_dev_pasid(&info->domain->domain,
>> + dev, IOMMU_NO_PASID);
>
> The function name is self-explained. So no need to add comments. Ditto
> to all other places.
>
Indeed.
I'll delete all related comments.
Thanks,
Jingqi
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