On Wed, Jul 10, 2019 at 12:14:44PM +0000, Liu, Yi L wrote: > > From: Peter Xu [mailto:zhexu@xxxxxxxxxx] > > Sent: Tuesday, July 9, 2019 10:16 AM > > To: Liu, Yi L <yi.l.liu@xxxxxxxxx> > > Subject: Re: [RFC v1 04/18] intel_iommu: add "sm_model" option > > > > On Fri, Jul 05, 2019 at 07:01:37PM +0800, Liu Yi L wrote: > > > Intel VT-d 3.0 introduces scalable mode, and it has a bunch of > > > capabilities related to scalable mode translation, thus there > > > are multiple combinations. While this vIOMMU implementation > > > wants simplify it for user by providing typical combinations. > > > User could config it by "sm_model" option. The usage is as > > > below: > > > > > > "-device intel-iommu,x-scalable-mode=on,sm_model=["legacy"|"scalable"]" > > > > Is it a requirement to split into two parameters, instead of just > > exposing everything about scalable mode when x-scalable-mode is set? > > yes, it is. Scalable mode has multiple capabilities. And we want to support > the most typical combinations to simplify software. e.g. current scalable mode > vIOMMU exposes only 2nd level translation to guest, and guest IOVA support > is via shadowing guest 2nd level page table. We have plan to move IOVA from > 2nd level page table to 1st level page table, thus guest IOVA can be supported > with nested translation. And this also addresses the co-existence issue of guest > SVA and guest IOVA. So in future we will have scalable mode vIOMMU expose > 1st level translation only. To differentiate this config with current vIOMMU, > we need an extra option to control it. But yes, it is still scalable mode vIOMMU. > just has different capability exposed to guest. I see. Thanks for explaining. > > BTW. do you know if I can add sub-options under "x-scalable-mode"? I think > that may demonstrate the dependency better. I'm not an expert of that, but I think at least we can make it a string parameter depends on what you prefer, then we can do "x-scalable-mode=legacy|modern". Or keep this would be fine too. > > > > > > > - "legacy": gives support for SL page table > > > - "scalable": gives support for FL page table, pasid, virtual command > > > - default to be "legacy" if "x-scalable-mode=on while no sm_model is > > > configured > > > > > > Cc: Kevin Tian <kevin.tian@xxxxxxxxx> > > > Cc: Jacob Pan <jacob.jun.pan@xxxxxxxxxxxxxxx> > > > Cc: Peter Xu <peterx@xxxxxxxxxx> > > > Cc: Yi Sun <yi.y.sun@xxxxxxxxxxxxxxx> > > > Signed-off-by: Liu Yi L <yi.l.liu@xxxxxxxxx> > > > Signed-off-by: Yi Sun <yi.y.sun@xxxxxxxxxxxxxxx> > > > --- > > > hw/i386/intel_iommu.c | 28 +++++++++++++++++++++++++++- > > > hw/i386/intel_iommu_internal.h | 2 ++ > > > include/hw/i386/intel_iommu.h | 1 + > > > 3 files changed, 30 insertions(+), 1 deletion(-) > > > > > > diff --git a/hw/i386/intel_iommu.c b/hw/i386/intel_iommu.c > > > index 44b1231..3160a05 100644 > > > --- a/hw/i386/intel_iommu.c > > > +++ b/hw/i386/intel_iommu.c > > > @@ -3014,6 +3014,7 @@ static Property vtd_properties[] = { > > > DEFINE_PROP_BOOL("caching-mode", IntelIOMMUState, caching_mode, > > FALSE), > > > DEFINE_PROP_BOOL("x-scalable-mode", IntelIOMMUState, scalable_mode, > > FALSE), > > > DEFINE_PROP_BOOL("dma-drain", IntelIOMMUState, dma_drain, true), > > > + DEFINE_PROP_STRING("sm_model", IntelIOMMUState, sm_model), > > > > Can do 's/-/_/' to follow the rest if we need it. > > Do you mean sub-options after "x-scalable-mode"? No, I only mean "sm-model". :) Regards, -- Peter Xu
