On Sat, May 17, 2025 at 08:21:27PM -0700, Nicolin Chen wrote: > The new HW QUEUE object will be added for HW to access the guest queue for > HW-accelerated virtualization feature. Some of HW QUEUEs are designed in a > way of accessing the guest queue via a host physical address without doing > a translation using the nesting parent IO page table, while others can use > the guest physical address. For the former case, kernel working with a VMM > needs to pin the physical pages backing the guest memory to lock them when > HW QUEUE is accessing, and to ensure those physical pages to be contiguous > in the 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 HW QUEUE allocator. > > 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. > > Reviewed-by: Pranjal Shrivastava <pr...@google.com> > Reviewed-by: Kevin Tian <kevin.t...@intel.com> > Reviewed-by: Jason Gunthorpe <j...@nvidia.com> > Signed-off-by: Nicolin Chen <nicol...@nvidia.com> > --- > drivers/iommu/iommufd/io_pagetable.h | 8 ++ > drivers/iommu/iommufd/iommufd_private.h | 6 ++ > drivers/iommu/iommufd/device.c | 119 ++---------------------- > drivers/iommu/iommufd/io_pagetable.c | 97 +++++++++++++++++++ > 4 files changed, 119 insertions(+), 111 deletions(-)
And if you do what was suggested do we need this patch at all? Just use the normal access sequence: iommufd_access_create(ops=NULL) iommufd_access_attach(viommu->hwpt->ioas) iommufd_access_pin_pages() And store a viommu->access pointer to undo it all. This avoids making it all special with different internal behavior from a mdev. The only difference is we allowe ops=null for viommu but not for mdev. I don't think it is worth doing all these changes just to eliminate the access memory allocation.. viommu allocation is not fast path. Jason
