[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v2] xen: arm: process XENMEM_add_to_physmap_range forwards not backwards.
>>> On 18.12.13 at 14:39, Ian Campbell <ian.campbell@xxxxxxxxxx> wrote: > Jan points out that processing the list backwards is rather counter intuitive > and that the effect of the hypercall can differ between forwards and > backwards > processing (e.g. in the presence of duplicate idx or gpfn, which would be > unusualy but as Jan says, users are a creative bunch) > > Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx> > Cc: Mukesh Rathor <mukesh.rathor@xxxxxxxxxx> > --- > v2: Remember to crank the errs array too. > > Resending despite abuse of overwriting the IN paramters, since coming to > rely on backwards processing is a harder hole to get out of than going > from modifying the strict to not. > > Release: subtle ABI change, should go in to 4.4 before people rely on it > (they > are not relying on it today TTBOMK and it seems unlikely but lets not risk > it) > --- > xen/arch/arm/mm.c | 13 ++++++------- > 1 file changed, 6 insertions(+), 7 deletions(-) > > diff --git a/xen/arch/arm/mm.c b/xen/arch/arm/mm.c > index e235364..f1b7099 100644 > --- a/xen/arch/arm/mm.c > +++ b/xen/arch/arm/mm.c > @@ -1062,21 +1062,18 @@ static int xenmem_add_to_physmap_range(struct domain > *d, > { > int rc; > > - /* Process entries in reverse order to allow continuations */ > while ( xatpr->size > 0 ) > { > xen_ulong_t idx; > xen_pfn_t gpfn; > > - if ( unlikely(copy_from_guest_offset(&idx, xatpr->idxs, > - xatpr->size-1, 1)) ) > + if ( unlikely(copy_from_guest_offset(&idx, xatpr->idxs, 0, 1)) ) > { > rc = -EFAULT; > goto out; > } > > - if ( unlikely(copy_from_guest_offset(&gpfn, xatpr->gpfns, > - xatpr->size-1, 1)) ) > + if ( unlikely(copy_from_guest_offset(&gpfn, xatpr->gpfns, 0, 1)) ) > { > rc = -EFAULT; > goto out; > @@ -1086,8 +1083,7 @@ static int xenmem_add_to_physmap_range(struct domain > *d, > xatpr->foreign_domid, > idx, gpfn); > > - if ( unlikely(copy_to_guest_offset(xatpr->errs, > - xatpr->size-1, &rc, 1)) ) > + if ( unlikely(copy_to_guest_offset(xatpr->errs, 0, &rc, 1)) ) > { > rc = -EFAULT; > goto out; > @@ -1096,6 +1092,9 @@ static int xenmem_add_to_physmap_range(struct domain > *d, > if ( rc < 0 ) > goto out; > > + guest_handle_add_offset(xatpr->idxs, 1); > + guest_handle_add_offset(xatpr->gpfns, 1); > + guest_handle_add_offset(xatpr->errs, 1); > xatpr->size--; > > /* Check for continuation if it's not the last interation */ > -- > 1.7.10.4 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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