Re: [RFC PATCH 2/5] iommu/vt-d: Add generic IO page table support
On Thu, Nov 09, 2023 at 12:10:59AM +, Zhang, Tina wrote: > > 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. Well, it structures the code in a similar way to all the other drivers, though I admit to having not looked closely at the io page table stuff. > 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. I would like to de-virtualize those callbacks, is is completely pointless when we have per-format iommu_domain ops now. Jason
RE: [RFC PATCH 2/5] iommu/vt-d: Add generic IO page table support
Hi Jason, > -Original Message- > From: Jason Gunthorpe > Sent: Tuesday, November 7, 2023 3:32 AM > To: Zhang, Tina > Cc: Jean-Philippe Brucker ; Tian, Kevin > ; Lu Baolu ; j...@8bytes.org; > w...@kernel.org; Liu, Yi L ; virtualization@lists.linux- > foundation.org; io...@lists.linux.dev; linux-ker...@vger.kernel.org > 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 > > --- > > 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
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 > --- > 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? Jason ___ Virtualization mailing list Virtualization@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/virtualization
