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Message-ID: <5f845a90-97ba-e994-c8b9-91fc6f3ea1c1@linux.intel.com>
Date: Sun, 24 Jul 2022 15:23:19 +0800
From: Baolu Lu <baolu.lu@...ux.intel.com>
To: Jason Gunthorpe <jgg@...dia.com>
Cc: baolu.lu@...ux.intel.com, Joerg Roedel <joro@...tes.org>,
Christoph Hellwig <hch@...radead.org>,
Kevin Tian <kevin.tian@...el.com>,
Ashok Raj <ashok.raj@...el.com>, Will Deacon <will@...nel.org>,
Robin Murphy <robin.murphy@....com>,
Jean-Philippe Brucker <jean-philippe@...aro.com>,
Dave Jiang <dave.jiang@...el.com>,
Vinod Koul <vkoul@...nel.org>,
Eric Auger <eric.auger@...hat.com>,
Liu Yi L <yi.l.liu@...el.com>,
Jacob jun Pan <jacob.jun.pan@...el.com>,
Zhangfei Gao <zhangfei.gao@...aro.org>,
Zhu Tony <tony.zhu@...el.com>, iommu@...ts.linux.dev,
linux-kernel@...r.kernel.org,
Jean-Philippe Brucker <jean-philippe@...aro.org>
Subject: Re: [PATCH v10 04/12] iommu: Add attach/detach_dev_pasid iommu
interface
On 2022/7/23 22:11, Jason Gunthorpe wrote:
>> +
>> + /*
>> + * Otherwise, the device came from DT/ACPI, assume it is static and
>> + * then singleton can know from the device count in the group.
>> + */
>> + return true;
>> +}
> I would be happer if probe was changed to refuse to add a device to a
> group if the group's pasid xarray is not empty, as a protective
> measure.
Agreed. I will add below code.
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 047898666b9f..e43cb6776087 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -895,6 +895,14 @@ int iommu_group_add_device(struct iommu_group
*group, struct device *dev)
int ret, i = 0;
struct group_device *device;
+ /*
+ * The iommu_attach_device_pasid() requires a singleton group.
+ * Refuse to add a device into it if this assumption has been
+ * made.
+ */
+ if (!xa_empty(group->pasid_array))
+ return -EBUSY;
+
device = kzalloc(sizeof(*device), GFP_KERNEL);
if (!device)
return -ENOMEM;
>
>> +int iommu_attach_device_pasid(struct iommu_domain *domain, struct device *dev,
>> + ioasid_t pasid)
>> +{
>> + struct iommu_group *group;
>> + void *curr;
>> + int ret;
>> +
>> + if (!domain->ops->set_dev_pasid)
>> + return -EOPNOTSUPP;
>> +
>> + group = iommu_group_get(dev);
>> + if (!group || !iommu_group_immutable_singleton(group, dev)) {
>> + iommu_group_put(group);
>> + return -EINVAL;
> goto error below
>
>> + }
>> +
>> + mutex_lock(&group->mutex);
> Just hold the group->mutex a few lines above and don't put locking in
> iommu_group_immutable_singleton(), it is clearer
Above two comments agreed. iommu_attach_device_pasid() looks like below
after update.
int iommu_attach_device_pasid(struct iommu_domain *domain, struct device
*dev,
ioasid_t pasid)
{
struct iommu_group *group;
int ret = -EINVAL;
void *curr;
if (!domain->ops->set_dev_pasid)
return -EOPNOTSUPP;
group = iommu_group_get(dev);
if (!group)
return -ENODEV;
mutex_lock(&group->mutex);
if (!iommu_group_immutable_singleton(group, dev))
goto out_unlock;
curr = xa_cmpxchg(&group->pasid_array, pasid, NULL, domain,
GFP_KERNEL);
if (curr) {
ret = xa_err(curr) ? : -EBUSY;
goto out_unlock;
}
ret = domain->ops->set_dev_pasid(domain, dev, pasid);
if (ret)
xa_erase(&group->pasid_array, pasid);
out_unlock:
mutex_unlock(&group->mutex);
iommu_group_put(group);
return ret;
}
Best regards,
baolu
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