Re: [PATCH v2 01/22] iommu: Add iommu_user_domain_alloc() interface
From: Yi Liu
Date: Wed Jun 05 2024 - 02:20:26 EST
On 2024/6/5 10:00, Baolu Lu wrote:
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@xxxxxxxxxxxxxxx>
---
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?
yes. As I replied in last version, user_domain is a bit confusing since
nested domain is also a user_domain. That's why we introduced the
alloc_domain_user op.
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.
do you mean user_domain only includes paging domain?
+ */
+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?
I think so. This should work.
--
Regards,
Yi Liu