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Message-ID: <91a42f46-060a-4430-a10a-7bfded67c4a9@linux.intel.com>
Date: Wed, 5 Jun 2024 10:00:09 +0800
From: Baolu Lu <baolu.lu@...ux.intel.com>
To: Yi Liu <yi.l.liu@...el.com>, Joerg Roedel <joro@...tes.org>,
Will Deacon <will@...nel.org>, Robin Murphy <robin.murphy@....com>,
Jason Gunthorpe <jgg@...pe.ca>, Kevin Tian <kevin.tian@...el.com>
Cc: baolu.lu@...ux.intel.com, David Airlie <airlied@...il.com>,
Daniel Vetter <daniel@...ll.ch>, Kalle Valo <kvalo@...nel.org>,
Bjorn Andersson <andersson@...nel.org>,
Mathieu Poirier <mathieu.poirier@...aro.org>,
Alex Williamson <alex.williamson@...hat.com>, mst@...hat.com,
Jason Wang <jasowang@...hat.com>, Thierry Reding <thierry.reding@...il.com>,
Jonathan Hunter <jonathanh@...dia.com>,
Mikko Perttunen <mperttunen@...dia.com>, iommu@...ts.linux.dev,
dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 01/22] iommu: Add iommu_user_domain_alloc() interface
On 6/4/24 4:03 PM, Yi Liu wrote:
> On 2024/6/4 09:51, Lu Baolu wrote:
>> Commit <909f4abd1097> ("iommu: Add new iommu op to create domains owned
>> by userspace") added a dedicated iommu op to allocate a user domain.
>> While IOMMUFD has already made use of this callback, other frameworks
>> like vfio/type1 and vDPA still use the paging domain allocation
>> interface.
>>
>> Add a new interface named iommu_user_domain_alloc(), which indicates the
>> allocation of a domain for device DMA managed by user space driver. All
>> device passthrough frameworks could use this interface for their domain
>> allocation.
>>
>> Although it is expected that all iommu drivers could implement their own
>> domain_alloc_user ops, most drivers haven't implemented it yet. Rollback
>> to the paging domain allocation interface if the iommu driver hasn't
>> implemented this op yet.
>>
>> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
>> ---
>> include/linux/iommu.h | 6 ++++++
>> drivers/iommu/iommu.c | 42 ++++++++++++++++++++++++++++++++++++++++++
>> 2 files changed, 48 insertions(+)
>>
>> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
>> index 7bc8dff7cf6d..6648b2415474 100644
>> --- a/include/linux/iommu.h
>> +++ b/include/linux/iommu.h
>> @@ -780,6 +780,7 @@ extern bool iommu_present(const struct bus_type
>> *bus);
>> extern bool device_iommu_capable(struct device *dev, enum iommu_cap
>> cap);
>> extern bool iommu_group_has_isolated_msi(struct iommu_group *group);
>> extern struct iommu_domain *iommu_domain_alloc(const struct bus_type
>> *bus);
>> +struct iommu_domain *iommu_user_domain_alloc(struct device *dev, u32
>> flags);
>> extern void iommu_domain_free(struct iommu_domain *domain);
>> extern int iommu_attach_device(struct iommu_domain *domain,
>> struct device *dev);
>> @@ -1086,6 +1087,11 @@ static inline struct iommu_domain
>> *iommu_domain_alloc(const struct bus_type *bus
>> return NULL;
>> }
>> +static inline struct iommu_domain *iommu_user_domain_alloc(struct
>> device *dev, u32 flags)
>> +{
>> + return ERR_PTR(-ENODEV);
>> +}
>> +
>> static inline void iommu_domain_free(struct iommu_domain *domain)
>> {
>> }
>> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
>> index 9df7cc75c1bc..f1416892ef8e 100644
>> --- a/drivers/iommu/iommu.c
>> +++ b/drivers/iommu/iommu.c
>> @@ -2032,6 +2032,48 @@ struct iommu_domain *iommu_domain_alloc(const
>> struct bus_type *bus)
>> }
>> EXPORT_SYMBOL_GPL(iommu_domain_alloc);
>> +/**
>> + * iommu_user_domain_alloc() - Allocate a user domain
>> + * @dev: device for which the domain is allocated
>> + * @flags: iommufd_hwpt_alloc_flags defined in uapi/linux/iommufd.h
>> + *
>> + * Allocate a user domain which will be managed by a userspace
>> driver. Return
>> + * allocated domain if successful, or a ERR pointer for failure.
>
> do you want to mention that this is for paging domain allocation?
You are worrying about its confusion with nesting domain allocation,
right? My understanding is that if we want a common interface for
nesting domain allocation, we should make it in another interface. Here,
the user domain is a paging domain for GVA->HPA mapping, which is common
across iommufd, vfio, and vdpa.
>
>> + */
>> +struct iommu_domain *iommu_user_domain_alloc(struct device *dev, u32
>> flags)
>> +{
>> + struct iommu_domain *domain;
>> + const struct iommu_ops *ops;
>> +
>> + if (!dev_has_iommu(dev))
>> + return ERR_PTR(-ENODEV);
>> +
>> + ops = dev_iommu_ops(dev);
>> + if (ops->domain_alloc_user) {
>> + domain = ops->domain_alloc_user(dev, flags, NULL, NULL);
>> + if (IS_ERR(domain))
>> + return domain;
>> +
>> + domain->type = IOMMU_DOMAIN_UNMANAGED;
>> + domain->owner = ops;
>> + domain->pgsize_bitmap = ops->pgsize_bitmap;
>
> this seems to break the iommufd selftest as the mock driver sets extra
> bits in the domain->pgsize_bitmap in allocation. Override it may fail
> something in the testing. you may need to check if domain->pgsize_bitmap
> is set or use &=.
>
> static struct iommu_domain *mock_domain_alloc_paging(struct device *dev)
> {
> struct mock_dev *mdev = container_of(dev, struct mock_dev, dev);
> struct mock_iommu_domain *mock;
>
> mock = kzalloc(sizeof(*mock), GFP_KERNEL);
> if (!mock)
> return NULL;
> mock->domain.geometry.aperture_start = MOCK_APERTURE_START;
> mock->domain.geometry.aperture_end = MOCK_APERTURE_LAST;
> mock->domain.pgsize_bitmap = MOCK_IO_PAGE_SIZE;
> if (dev && mdev->flags & MOCK_FLAGS_DEVICE_HUGE_IOVA)
> mock->domain.pgsize_bitmap |= MOCK_HUGE_PAGE_SIZE;
> mock->domain.ops = mock_ops.default_domain_ops;
> mock->domain.type = IOMMU_DOMAIN_UNMANAGED;
> xa_init(&mock->pfns);
> return &mock->domain;
> }
You are right. I should follow the code in __iommu_domain_alloc()
/*
* If not already set, assume all sizes by default; the driver
* may override this later
*/
if (!domain->pgsize_bitmap)
domain->pgsize_bitmap = ops->pgsize_bitmap;
Does it work?
Best regards,
baolu
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