> From: Nicolin Chen <nicolinc@xxxxxxxxxx> > Sent: Wednesday, May 7, 2025 3:18 AM > > On Tue, May 06, 2025 at 09:36:38AM +0000, Tian, Kevin wrote: > > > From: Nicolin Chen <nicolinc@xxxxxxxxxx> > > > Sent: Saturday, April 26, 2025 1:58 PM > > > > > > The new vCMDQ object will be added for HW to access the guest memory > for > > > a > > > HW-accelerated virtualization feature. It needs to ensure the guest > memory > > > pages are pinned when HW accesses them and they are contiguous in > > > physical > > > address space. > > > > > > This is very like the existing iommufd_access_pin_pages() that outputs > the > > > pinned page list for the caller to test its contiguity. > > > > > > Move those code from iommufd_access_pin/unpin_pages() and related > > > function > > > for a pair of iopt helpers that can be shared with the vCMDQ allocator. As > > > the vCMDQ allocator will be a user-space triggered ioctl function, > WARN_ON > > > would not be a good fit in the new iopt_unpin_pages(), thus change them > to > > > use WARN_ON_ONCE instead. > > > > > > Rename check_area_prot() to align with the existing iopt_area helpers, > and > > > inline it to the header since iommufd_access_rw() still uses it. > > > > > > Signed-off-by: Nicolin Chen <nicolinc@xxxxxxxxxx> > > > > any reason why this cannot be done by the core? all types of vcmd > > queues need to pin the guest buffer pages, no matter the IOMMU > > accesses GPA or HPA. > > > > Jason made a similar comment earlier [1]. > > > > check of continuity is still done by the driver, if HPA is being accessed. > > > > [1] https://lore.kernel.org/all/20250424134049.GP1648741@xxxxxxxxxx/ > > But I am doing in the core. I have iopt_pin_pages() called in the > core ioctl handler iommufd_vqueue_alloc_ioctl(): > > https://lore.kernel.org/linux- > iommu/1ef2e242ee1d844f823581a5365823d78c67ec6a.1746139811.git.nicoli > nc@xxxxxxxxxx/ > IMHO we just want to keep the pin logic in the core while leaving the check of PFN continuity to the driver (or have a way for the driver to communicate such need to the core). It's possible for have an implementation with IOMMU accessing GPA of the queue which further goes through the stage-2 translation. In such case it's fine to have disjointed PFNs.
