> -----Original Message----- > From: Jan Beulich [mailto:jbeul...@suse.com] > Sent: 09 August 2018 10:09 > 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 v22 1/2] common: add a new mappable resource type: > XENMEM_resource_grant_table > > >>> On 09.08.18 at 11:07, wrote: > >>>> On 09.08.18 at 10:55, <paul.durr...@citrix.com> wrote: > > >> From: Jan Beulich [mailto:jbeul...@suse.com] > > >> Sent: 09 August 2018 09:47 > > >> > > >> >>> On 08.08.18 at 16:16, <paul.durr...@citrix.com> wrote: > > >> > @@ -1046,6 +1090,16 @@ static int acquire_resource( > > >> > xen_pfn_t gfn_list[ARRAY_SIZE(mfn_list)]; > > >> > unsigned int i; > > >> > > > >> > + /* > > >> > + * FIXME: Until foreign pages inserted into the P2M are > > >> > properly > > >> > + * reference counted, it is unsafe to allow mapping of > > >> > + * non-caller-owned resource pages unless the caller is > > >> > + * the hardware domain. > > >> > + */ > > >> > + if ( !(xmar.flags & XENMEM_rsrc_acq_caller_owned) && > > >> > + !is_hardware_domain(currd) ) > > >> > + return -EOPNOTSUPP; > > >> > + > > >> > > >> Now that I look at this again - wouldn't this check better live ahead > > >> of the main switch()? I find it odd, for example, that in this case the > > >> grant table would still have got grown. > > > > > > This can't live ahead of the main switch because > > > XENMEM_rsrc_acq_caller_owned is passed-out flag, not a passed-in one. > > > > Oh, right. Except that only arch_acquire_resource() could currently > > set the flag, and hence from this patch's perspective it's not visible > > that this is an "out" flag. I guess you mean to set the flag in > > acquire_grant_table() or next to the call to it. > > Rubbish - the flag is supposed to be clear here. I'm sorry for the noise. >
I was just poised to say that :-) Paul > Jan > _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
