RE: [PATCH v5 4/8] iommu: make map and unmap take a page count, similar to flush

[Paul Durrant <xadimgnik@gmail.com>]

> -----Original Message-----
> From: Jan Beulich <jbeulich@suse.com>
> Sent: 10 September 2020 13:48
> To: Paul Durrant <paul@xen.org>
> Cc: xen-devel@lists.xenproject.org; Paul Durrant <pdurrant@amazon.com>; Andrew Cooper
> <andrew.cooper3@citrix.com>; Wei Liu <wl@xen.org>; Roger Pau Monné <roger.pau@citrix.com>; George
> Dunlap <george.dunlap@citrix.com>; Ian Jackson <ian.jackson@eu.citrix.com>; Julien Grall
> <julien@xen.org>; Stefano Stabellini <sstabellini@kernel.org>; Jun Nakajima <jun.nakajima@intel.com>;
> Kevin Tian <kevin.tian@intel.com>
> Subject: Re: [PATCH v5 4/8] iommu: make map and unmap take a page count, similar to flush
> 
> On 07.09.2020 09:40, Paul Durrant wrote:
> > --- a/xen/arch/x86/mm.c
> > +++ b/xen/arch/x86/mm.c
> > @@ -2966,9 +2966,11 @@ static int _get_page_type(struct page_info *page, unsigned long type,
> >              mfn_t mfn = page_to_mfn(page);
> >
> >              if ( (x & PGT_type_mask) == PGT_writable_page )
> > -                rc = iommu_legacy_unmap(d, _dfn(mfn_x(mfn)), PAGE_ORDER_4K);
> > +                rc = iommu_legacy_unmap(d, _dfn(mfn_x(mfn)),
> > +                                        1ul << PAGE_ORDER_4K);
> >              else
> > -                rc = iommu_legacy_map(d, _dfn(mfn_x(mfn)), mfn, PAGE_ORDER_4K,
> > +                rc = iommu_legacy_map(d, _dfn(mfn_x(mfn)), mfn,
> > +                                      1ul << PAGE_ORDER_4K,
> >                                        IOMMUF_readable | IOMMUF_writable);
> >
> >              if ( unlikely(rc) )
> 
> A few hundred lines up from here there is
> 
>             int rc2 = iommu_legacy_unmap(d, _dfn(mfn), PAGE_ORDER_4K);
> 
> in cleanup_page_mappings().

Oh yes. Fixed.

> 
> > --- a/xen/common/grant_table.c
> > +++ b/xen/common/grant_table.c
> > @@ -1225,7 +1225,7 @@ map_grant_ref(
> >              kind = IOMMUF_readable;
> >          else
> >              kind = 0;
> > -        if ( kind && iommu_legacy_map(ld, _dfn(mfn_x(mfn)), mfn, 0, kind) )
> > +        if ( kind && iommu_legacy_map(ld, _dfn(mfn_x(mfn)), mfn, 1ul, kind) )
> >          {
> >              double_gt_unlock(lgt, rgt);
> >              rc = GNTST_general_error;
> > @@ -1479,9 +1479,9 @@ unmap_common(
> >
> >          kind = mapkind(lgt, rd, op->mfn);
> >          if ( !kind )
> > -            err = iommu_legacy_unmap(ld, _dfn(mfn_x(op->mfn)), 0);
> > +            err = iommu_legacy_unmap(ld, _dfn(mfn_x(op->mfn)), 1ul);
> >          else if ( !(kind & MAPKIND_WRITE) )
> > -            err = iommu_legacy_map(ld, _dfn(mfn_x(op->mfn)), op->mfn, 0,
> > +            err = iommu_legacy_map(ld, _dfn(mfn_x(op->mfn)), op->mfn, 1ul,
> 
> For all three of these, I guess either 1ul << PAGE_ORDER_4K or simply 1?
> (Given that the code didn't use PAGE_ORDER_4K so far, I'd slightly
> prefer the latter. I'd be fine making the change while committing, but
> it looks like v6 is going to be needed anyway.)

Ok. Changed.

> 
> > --- a/xen/drivers/passthrough/amd/iommu_map.c
> > +++ b/xen/drivers/passthrough/amd/iommu_map.c
> > @@ -362,7 +362,7 @@ static unsigned long flush_count(unsigned long dfn, unsigned int page_count,
> >  }
> >
> >  int amd_iommu_flush_iotlb_pages(struct domain *d, dfn_t dfn,
> > -                                unsigned int page_count,
> > +                                unsigned long page_count,
> 
> This ought to be accompanied by a similar change to its flush_count()
> helper.
> 
> > @@ -632,7 +632,7 @@ static int __must_check iommu_flush_iotlb(struct domain *d, dfn_t dfn,
>
> >  static int __must_check iommu_flush_iotlb_pages(struct domain *d,
> >                                                  dfn_t dfn,
> > -                                                unsigned int page_count,
> > +                                                unsigned long page_count,
> >                                                  unsigned int flush_flags)
> >  {
> >      ASSERT(page_count && !dfn_eq(dfn, INVALID_DFN));
> 
> This similarly ought to be accompanied by a change to its
> iommu_flush_iotlb() helper.
> 

It is... in the previous hunk.

  Paul

> Jan