> -----Original Message----- > From: Jan Beulich [mailto:jbeul...@suse.com] > Sent: 04 September 2018 13:55 > To: Paul Durrant <paul.durr...@citrix.com> > Cc: Andrew Cooper <andrew.coop...@citrix.com>; George Dunlap > <george.dun...@citrix.com>; Ian Jackson <ian.jack...@citrix.com>; Wei Liu > <wei.l...@citrix.com>; Stefano Stabellini <sstabell...@kernel.org>; xen- > devel <xen-devel@lists.xenproject.org>; Konrad Rzeszutek Wilk > <konrad.w...@oracle.com>; Tim (Xen.org) <t...@xen.org> > Subject: RE: [PATCH v6 05/14] public / x86: introduce > __HYPERCALL_iommu_op > > >>> On 04.09.18 at 14:23, <paul.durr...@citrix.com> wrote: > >> From: Jan Beulich [mailto:jbeul...@suse.com] > >> Sent: 04 September 2018 12:50 > >> > >> >>> On 23.08.18 at 11:47, <paul.durr...@citrix.com> wrote: > >> > +int compat_one_iommu_op(compat_iommu_op_buf_t *buf) > >> > +{ > >> > + compat_iommu_op_t cmp; > >> > + xen_iommu_op_t nat; > >> > + int rc; > >> > + > >> > + if ( buf->size < sizeof(cmp) ) > >> > + return -EFAULT; > >> > + > >> > + if ( copy_from_compat((void *)&cmp, buf->h, sizeof(cmp)) ) > >> > + return -EFAULT; > >> > + > >> > + if ( cmp.pad ) > >> > + return -EINVAL; > >> > + > >> > + rc = xsm_iommu_op(XSM_PRIV, current->domain, cmp.op); > >> > + if ( rc ) > >> > + return rc; > >> > + > >> > + XLAT_iommu_op(&nat, &cmp); > >> > + > >> > + iommu_op(&nat); > >> > + > >> > + XLAT_iommu_op(&cmp, &nat); > >> > + > >> > + if ( __copy_field_to_compat(compat_handle_cast(buf->h, > >> > + compat_iommu_op_t), > >> > + &cmp, status) ) > >> > >> Since you're only after the status field, perhaps better to avoid the > >> full-blown reverse XLAT_iommu_op() and copy just that one field? > >> > > > > I kind of like the fact that the two calls mirror each other so I'd prefer > > to keep it. > > Would you mind looking at the generated code (once you have a few > sub-ops in place)? If the compiler manages to remove most of the > cruft, I'd be fine keeping it as is. If, however, a whole lot of extra > code gets generated, I'd really like to ask to use the shorter form. >
I checked... it's not wonderfully compact (because of the nested switches I guess), so I'll cherry-pick the status and add a comment. Paul > Jan > _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
