Hi Jason,
On 11/16/21 9:46 PM, Jason Gunthorpe wrote:
On Tue, Nov 16, 2021 at 09:57:30AM +0800, Lu Baolu wrote:
Hi Christoph,
On 11/15/21 9:14 PM, Christoph Hellwig wrote:
On Mon, Nov 15, 2021 at 10:05:42AM +0800, Lu Baolu wrote:
+enum iommu_dma_owner {
+ DMA_OWNER_NONE,
+ DMA_OWNER_KERNEL,
+ DMA_OWNER_USER,
+};
+
+ enum iommu_dma_owner dma_owner;
+ refcount_t owner_cnt;
+ struct file *owner_user_file;
I'd just overload the ownership into owner_user_file,
NULL -> no owner
(struct file *)1UL) -> kernel
real pointer -> user
Which could simplify a lot of the code dealing with the owner.
Yeah! Sounds reasonable. I will make this in the next version.
It would be good to figure out how to make iommu_attach_device()
enforce no other driver binding as a kernel user without a file *, as
Robin pointed to, before optimizing this.
This fixes an existing bug where iommu_attach_device() only checks the
group size and is vunerable to a hot plug increasing the group size
after it returns. That check should be replaced by this series's logic
instead.
As my my understanding, the essence of this problem is that only the
user owner of the iommu_group could attach an UNMANAGED domain to it.
If I understand it right, how about introducing a new interface to
allocate a user managed domain and storing the user file pointer in it.
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -94,6 +94,7 @@ struct iommu_domain {
void *handler_token;
struct iommu_domain_geometry geometry;
struct iommu_dma_cookie *iova_cookie;
+ struct file *owner_user_file;
};
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1902,6 +1902,18 @@ struct iommu_domain *iommu_domain_alloc(struct
bus_type *bus)
}
EXPORT_SYMBOL_GPL(iommu_domain_alloc);
+struct iommu_domain *iommu_domain_alloc_user(struct bus_type *bus,
+ struct file *filep)
+{
+ struct iommu_domain *domain;
+
+ domain = __iommu_domain_alloc(bus, IOMMU_DOMAIN_UNMANAGED);
+ if (domain)
+ domain->owner_user_file = filep;
+
+ return domain;
+}
When attaching a domain to an user-owned iommu_group, both group and
domain should have matched user fd.
Does above help here?
Best regards,
baolu
