Re: [PATCH RFC 06/11] iommu/sva: Use attach/detach_pasid_dev in SVA interfaces

Lu Baolu
2022-03-22T04:29:52Z

On 2022/3/21 19:33, Jean-Philippe Brucker wrote:
> On Sun, Mar 20, 2022 at 02:40:25PM +0800, Lu Baolu wrote:
>> diff --git a/drivers/iommu/iommu-sva-lib.c b/drivers/iommu/iommu-sva-lib.c
>> index 106506143896..47cf98e661ff 100644
>> --- a/drivers/iommu/iommu-sva-lib.c
>> +++ b/drivers/iommu/iommu-sva-lib.c
>> @@ -3,6 +3,8 @@
>> * Helpers for IOMMU drivers implementing SVA
>> */
>> #include <linux/mutex.h>
>> +#include <linux/iommu.h>
>> +#include <linux/slab.h>
>> #include <linux/sched/mm.h>
>>
>> #include "iommu-sva-lib.h"
>> @@ -69,3 +71,101 @@ struct mm_struct *iommu_sva_find(ioasid_t pasid)
>> return ioasid_find(&iommu_sva_pasid, pasid, __mmget_not_zero);
>> }
>> EXPORT_SYMBOL_GPL(iommu_sva_find);
>> +
>> +static struct iommu_domain *iommu_sva_domain_alloc(struct device *dev)
>> +{
>> + struct bus_type *bus = dev->bus;
>> + struct iommu_domain *domain;
>> +
>> + if (!bus || !bus->iommu_ops)
>> + return NULL;
>> +
>> + domain = bus->iommu_ops->domain_alloc(IOMMU_DOMAIN_SVA);
>> + if (domain)
>> + domain->type = IOMMU_DOMAIN_SVA;
>> +
>> + return domain;
>> +}
>> +
>> +/**
>> + * iommu_sva_bind_device() - Bind a process address space to a device
>> + * @dev: the device
>> + * @mm: the mm to bind, caller must hold a reference to it
>> + * @drvdata: opaque data pointer to pass to bind callback
>> + *
>> + * Create a bond between device and address space, allowing the device to access
>> + * the mm using the returned PASID. If a bond already exists between @device and
>> + * @mm, it is returned and an additional reference is taken.
> This is not true anymore, we return a different structure for each call.
>
>> Caller must call
>> + * iommu_sva_unbind_device() to release each reference.
>> + *
>> + * iommu_dev_enable_feature(dev, IOMMU_DEV_FEAT_SVA) must be called first, to
>> + * initialize the required SVA features.
>> + *
>> + * On error, returns an ERR_PTR value.
>> + */
>> +struct iommu_sva *
>> +iommu_sva_bind_device(struct device *dev, struct mm_struct *mm, void *drvdata)
>> +{
>> + int ret = -EINVAL;
>> + struct iommu_sva *handle;
>> + struct iommu_domain *domain;
>> +
>> + handle = kzalloc(sizeof(*handle), GFP_KERNEL);
>> + if (!handle)
>> + return ERR_PTR(-ENOMEM);
>> +
>> + ret = iommu_sva_alloc_pasid(mm, 1, (1U << dev->iommu->pasid_bits) - 1);
>> + if (ret)
>> + goto out;
>> +
>> + domain = iommu_sva_domain_alloc(dev);
>> + if (!domain) {
>> + ret = -ENOMEM;
>> + goto out;
>> + }
>> + domain->sva_cookie = mm;
>> +
>> + ret = iommu_attach_device_pasid(domain, dev, mm->pasid);
>> + if (ret)
>> + goto out_free_domain;
>> +
>> + handle->dev = dev;
>> + handle->domain = domain;
>> + handle->pasid = mm->pasid;
>> +
>> + return handle;
>> +
>> +out_free_domain:
>> + iommu_domain_free(domain);
>> +out:
>> + kfree(handle);
>> +
>> + return ERR_PTR(ret);
>> +}
>> +EXPORT_SYMBOL_GPL(iommu_sva_bind_device);
>> +
>> +/**
>> + * iommu_sva_unbind_device() - Remove a bond created with iommu_sva_bind_device
>> + * @handle: the handle returned by iommu_sva_bind_device()
>> + *
>> + * Put reference to a bond between device and address space.
> Same here. But I'd prefer keeping the old behavior so device drivers don't
> have to keep track of {dev, mm} pairs themselves.

Okay. Thank you for pointing this out. Let me figure it out in the next
version.

Best regards,
baolu