> From: Peter Xu [mailto:zhexu@xxxxxxxxxx] > Sent: Thursday, July 11, 2019 9:04 AM > To: Liu, Yi L <yi.l.liu@xxxxxxxxx> > Subject: Re: [RFC v1 04/18] intel_iommu: add "sm_model" option > > 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. you are welcome. :-) > > > > > 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. hmmm, it's a good idea. If we agree to change x-scalable-mode to be a string parameter. I think I can change it. > > > > > > > > > > - "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". :) got it. if we modify x-scalable-mode to be string, then sm-model would be removed. Regards, Yi Liu > Regards, > > -- > Peter Xu
