Hi Jason, > -----Original Message----- > From: Jason Gunthorpe <jgg@xxxxxxxx> > Sent: Tuesday, November 7, 2023 3:32 AM > To: Zhang, Tina <tina.zhang@xxxxxxxxx> > Cc: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx>; Tian, Kevin > <kevin.tian@xxxxxxxxx>; Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>; joro@xxxxxxxxxx; > will@xxxxxxxxxx; Liu, Yi L <yi.l.liu@xxxxxxxxx>; virtualization@lists.linux- > foundation.org; iommu@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx > Subject: Re: [RFC PATCH 2/5] iommu/vt-d: Add generic IO page table support > > On Mon, Nov 06, 2023 at 02:12:23AM -0500, Tina Zhang wrote: > > Add basic hook up code to implement generic IO page table framework. > > > > Signed-off-by: Tina Zhang <tina.zhang@xxxxxxxxx> > > --- > > drivers/iommu/intel/Kconfig | 1 + > > drivers/iommu/intel/iommu.c | 94 > > +++++++++++++++++++++++++++++++++++++ > > drivers/iommu/intel/iommu.h | 7 +++ > > drivers/iommu/io-pgtable.c | 3 ++ > > include/linux/io-pgtable.h | 2 + > > 5 files changed, 107 insertions(+) > > If this is going to happen can we also convert vt-d to actually use the io page > table stuff directly and shuffle the code around so it is structured like the rest of > the io page table implementations? Converting VT-d driver to use io page table involves much code change. I made a local version of it, and it didn't prove much benefit. VT-d only supports one 1st-stage IO pgtable format and one 2nd-stage IO pgtable format. So, the current IO pgtable handling operations seems more efficient comparing to adding another layer callbacks in them. We have a plan to add a new io_pgtable.c file under VT-d driver directory and use that file to collect IO pgtable related functions. But we want to hold on converting VT-d to use the IO page table directly unless we can see some benefits. Regards, -Tina > > Jason
