[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v6 08/14] vtd: add lookup_page method to iommu_ops
> -----Original Message----- > From: Paul Durrant > Sent: 12 September 2018 09:52 > To: Paul Durrant <Paul.Durrant@xxxxxxxxxx>; 'Jan Beulich' > <JBeulich@xxxxxxxx> > Cc: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>; Kevin Tian > <kevin.tian@xxxxxxxxx>; George Dunlap <George.Dunlap@xxxxxxxxxx> > Subject: RE: [PATCH v6 08/14] vtd: add lookup_page method to iommu_ops > > > -----Original Message----- > > From: Xen-devel [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxxx] On > Behalf > > Of Paul Durrant > > Sent: 12 September 2018 09:45 > > To: 'Jan Beulich' <JBeulich@xxxxxxxx> > > Cc: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx>; Kevin Tian > > <kevin.tian@xxxxxxxxx>; George Dunlap <George.Dunlap@xxxxxxxxxx> > > Subject: Re: [Xen-devel] [PATCH v6 08/14] vtd: add lookup_page method > to > > iommu_ops > > > > > -----Original Message----- > > > From: Jan Beulich [mailto:JBeulich@xxxxxxxx] > > > Sent: 12 September 2018 09:44 > > > To: Paul Durrant <Paul.Durrant@xxxxxxxxxx> > > > Cc: George Dunlap <George.Dunlap@xxxxxxxxxx>; Kevin Tian > > > <kevin.tian@xxxxxxxxx>; xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxxx> > > > Subject: RE: [PATCH v6 08/14] vtd: add lookup_page method to > > iommu_ops > > > > > > >>> On 12.09.18 at 10:31, <Paul.Durrant@xxxxxxxxxx> wrote: > > > >> From: Jan Beulich [mailto:JBeulich@xxxxxxxx] > > > >> Sent: 07 September 2018 12:11 > > > >> > > > >> >>> On 23.08.18 at 11:47, <paul.durrant@xxxxxxxxxx> wrote: > > > >> > This patch adds a new method to the VT-d IOMMU implementation > to > > > find > > > >> the > > > >> > MFN currently mapped by the specified BFN along with a wrapper > > > function > > > >> in > > > >> > generic IOMMU code to call the implementation if it exists. > > > >> > > > >> For this to go in, I think the AMD side of it wants to also be > > implemented. > > > >> > > > >> > --- a/xen/drivers/passthrough/iommu.c > > > >> > +++ b/xen/drivers/passthrough/iommu.c > > > >> > @@ -305,6 +305,17 @@ int iommu_unmap_page(struct domain *d, > > > bfn_t > > > >> bfn) > > > >> > return rc; > > > >> > } > > > >> > > > > >> > +int iommu_lookup_page(struct domain *d, bfn_t bfn, mfn_t *mfn, > > > >> > + unsigned int *flags) > > > >> > +{ > > > >> > + const struct domain_iommu *hd = dom_iommu(d); > > > >> > + > > > >> > + if ( !iommu_enabled || !hd->platform_ops ) > > > >> > + return -EOPNOTSUPP; > > > >> > + > > > >> > + return hd->platform_ops->lookup_page(d, bfn, mfn, flags); > > > >> > +} > > > >> > > > >> Shouldn't this be restricted to PV guests? HVM ones aren't supposed > > > >> to know about MFNs. > > > > > > > > Agreed, but I think this is the wrong level to be applying such a check: > > > > iommu_map_page() is supplied an MFN regardless of whether the > > domain > > > is PV or > > > > HVM, so I think it is reasonable for a lookup function to work in terms > > > > of > > > > MFNs. > > > > > > I don't mind much where the check sits, but ASSERT(!is_hvm_domain()), > > > if placed here, should not trigger. > > > > > > > It will though. I'm going to need to use this function for HVM guests after > > having done a GFN lookup. > > Sorry... I'm getting confused myself now. It won't fire because in my case the > domain here will always by PV (because it is the not the domain owning the > GFN). I still think this is the wrong level for such a check though, but I'll > put in > the ASSERT. > Actually, no I still don't think the ASSERT is correct. Why should we rule out HVM guests being able to use PV-IOMMU? Paul > Paul > > > > > Paul > > > > > Jan > > > > > > > > > _______________________________________________ > > Xen-devel mailing list > > Xen-devel@xxxxxxxxxxxxxxxxxxxx > > https://lists.xenproject.org/mailman/listinfo/xen-devel _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxx https://lists.xenproject.org/mailman/listinfo/xen-devel
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