[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v4 3/3] xen/arm: introduce XENFEAT_grant_map_identity
On Mon, 28 Jul 2014, Julien Grall wrote: > Hi Stefano, > > On 07/28/2014 11:16 AM, Stefano Stabellini wrote: > > The flag specifies that the hypervisor maps a grant page to guest > > physical address == machine address of the page in addition to the > > normal grant mapping address. > > > > Frontends are allowed to map the same page multiple times using multiple > > grant references. On the backend side it can be difficult to find out > > the physical address corresponding to a particular machine address, > > especially at the completation of a dma operation. To simplify address > > completion > > [..] > > > if ( err ) > > { > > @@ -941,9 +951,18 @@ __gnttab_unmap_common( > > int err = 0; > > mapcount(lgt, rd, op->frame, &wrc, &rdc); > > if ( (wrc + rdc) == 0 ) > > - err = iommu_unmap_page(ld, op->frame); > > - else if ( wrc == 0 ) > > - err = iommu_map_page(ld, op->frame, op->frame, > > IOMMUF_readable); > > + { > > + if ( is_domain_direct_mapped(ld) ) > > + err = arch_grant_unmap_page_identity(ld, op->frame); > > + else > > + err = iommu_unmap_page(ld, op->frame); > > + } else if ( wrc == 0 ) > > + { > > + if ( is_domain_direct_mapped(ld) ) > > + err = arch_grant_map_page_identity(ld, op->frame, 0); > > + else > > + err = iommu_map_page(ld, op->frame, op->frame, > > IOMMUF_readable); > > With this solution, iommu_map_page will never be called on ARM. It's > because gnttab_need_iommu_mapping is checking the domain is using direct > mapping. > > So, I think you can drop the iommu_map_page callback of the SMMU in > patch #2. OK. Should I keep your acked-by on that patch? _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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