Re: [PATCH v4 2/9] iommu: Replace sva_iommu with iommu_attach_handle
From: Baolu Lu
Date: Wed Apr 10 2024 - 02:13:48 EST
On 4/10/24 7:48 AM, Jason Gunthorpe wrote:
On Tue, Apr 09, 2024 at 10:11:28AM +0800, Baolu Lu wrote:
On 4/8/24 10:19 PM, Jason Gunthorpe wrote:
On Sat, Apr 06, 2024 at 02:09:34PM +0800, Baolu Lu wrote:
On 4/3/24 7:59 PM, Jason Gunthorpe wrote:
On Wed, Apr 03, 2024 at 09:15:12AM +0800, Lu Baolu wrote:
+ /* A bond already exists, just take a reference`. */
+ handle = iommu_attach_handle_get(group, iommu_mm->pasid);
+ if (handle) {
+ mutex_unlock(&iommu_sva_lock);
+ return handle;
}
At least in this context this is not enough we need to ensure that the
domain on the PASID is actually an SVA domain and it was installed by
this mechanism, not an iommufd domain for instance.
ie you probably need a type field in the iommu_attach_handle to tell
what the priv is.
Otherwise this seems like a great idea!
Yes, you are right. For the SVA case, I will add the following changes.
The IOMMUFD path will also need such enhancement. I will update it in
the next version.
The only use for this is the PRI callbacks right? Maybe instead of
adding a handle type let's just check domain->iopf_handler ?
Ie SVA will pass &ommu_sva_iopf_handler as its "type"
Sorry that I don't fully understand the proposal here.
I was talking specifically about the type field you suggested adding
to the handle struct.
Instead of adding a type field check the domain->iopf_handler to
determine the domain and thus handle type.
The problem is that the context code (SVA, IOMMUFD, etc.) needs to make
sure that the attach handle is really what it has installed during
domain attachment. The context code needs some mechanism to include some
kind of "owner cookie" in the attach handle, so that it could check
against it later for valid use.
Right, you have a derived struct for each user and you need a way to
check if casting from the general handle struct to the derived struct
is OK.
I'm suggesting using domain->iopf_handle as the type key.
Oh, I see. It works. Thanks!
Best regards,
baolu