Re: [PATCH v2 1/2] iommu/vt-d: Use ida to manage domain id

[Jason Gunthorpe <jgg@ziepe.ca>]

On Wed, Apr 30, 2025 at 10:11:34AM +0800, Lu Baolu wrote:
> Switch the intel iommu driver to use the ida mechanism for managing domain
> IDs, replacing the previous fixed-size bitmap.
> 
> The previous approach allocated a bitmap large enough to cover the maximum
> number of domain IDs supported by the hardware, regardless of the actual
> number of domains in use. This led to unnecessary memory consumption,
> especially on systems supporting a large number of iommu units but only
> utilizing a small number of domain IDs.
> 
> The ida allocator dynamically manages the allocation and freeing of integer
> IDs, only consuming memory for the IDs that are currently in use. This
> significantly optimizes memory usage compared to the fixed-size bitmap.
> 
> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
> Reviewed-by: Kevin Tian <kevin.tian@intel.com>
> ---
>  drivers/iommu/intel/dmar.c  |  3 ++
>  drivers/iommu/intel/iommu.c | 80 ++++++++-----------------------------
>  drivers/iommu/intel/iommu.h | 19 +++++++--
>  3 files changed, 34 insertions(+), 68 deletions(-)

Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>

Jason