On May 24, 2016 3:09 PM, Tian, Kevin <kevin.t...@intel.com> wrote: > > From: Jan Beulich [mailto:jbeul...@suse.com] > > Sent: Tuesday, May 24, 2016 3:02 PM > > > > >>> On 24.05.16 at 03:16, <quan...@intel.com> wrote: > > > On May 24, 2016 12:06 AM, Jan Beulich <jbeul...@suse.com> wrote: > > >> >>> On 18.05.16 at 10:08, <quan...@intel.com> wrote: > > >> > --- a/xen/common/memory.c > > >> > +++ b/xen/common/memory.c > > >> > @@ -633,9 +633,9 @@ static long > > >> > memory_exchange(XEN_GUEST_HANDLE_PARAM(xen_memory_exchange_t) > > >> arg) > > >> > return rc; > > >> > } > > >> > > > >> > -static int xenmem_add_to_physmap(struct domain *d, > > >> > - struct xen_add_to_physmap *xatp, > > >> > - unsigned int start) > > >> > +static int __must_check xenmem_add_to_physmap(struct domain *d, > > >> > + struct > > >> > +xen_add_to_physmap > > > *xatp, > > >> > + unsigned int > > >> > + start) > > >> > { > > >> > > >> As before - either you do this adding of annotations completely, or > > >> you stop > > > at > > >> the IOMMU / MM boundary. > > > > > > I prefer to stop at the IOMMU / MM boundary. The IOMMU boundary is > > > obvious, but what's the definition of MM boundary? I thought this is at > MM boundary. > > > > Not sure what you mean to understand. The IOMMU / MM boundary is the > > boundary between those two components, there's no talk of two > > boundaries here, and hence the question is unclear to me. > > > > Jan > > Hi, Quan, > > A file-based map about IOMMU/MM boundary is under arch/x86/mm. You > need focus on low-level interaction between IOMMU and MM components, > i.e. when some state change in MM code (mostly p2m change) needs to > conduct IOMMU operations. > > Above xenmem is much higher level, which will be routed to various MM > operations internally so you don't need bother here.
Jan / Kevin, I thought the IOMMU / MM boundary is the MM functions (high level callers) which call iommu_* interfaces (such as, iommu_map_page / iommu_unmap_page / iommu_iotlb_flush ...). For this case, the xenmem_add_to_physmap() indeed calls iommu_iotlb_flush(), but xenmem_add_to_physmap() may be hypervisor interface, instead of MM interface. If I drop this __must_check and fix patch 3 / patch 5, then I think __must_check would not be a block issue. Quan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org http://lists.xen.org/xen-devel
