On 2016/4/7 18:32, Julien Grall wrote: > Hi Shannon, > > On 07/04/16 02:37, Shannon Zhao wrote: >> >> >> On 2016/4/6 20:16, Julien Grall wrote: >>>> + gpfns[j] = XEN_PFN_DOWN(r->start) + j; >>>> + idxs[j] = XEN_PFN_DOWN(r->start) + j; >>>> + } >>>> + >>>> + xatp.domid = DOMID_SELF; >>>> + xatp.size = nr; >>>> + xatp.space = XENMAPSPACE_dev_mmio; >>>> + >>>> + set_xen_guest_handle(xatp.gpfns, gpfns); >>>> + set_xen_guest_handle(xatp.idxs, idxs); >>>> + set_xen_guest_handle(xatp.errs, errs); >>>> + >>>> + rc = HYPERVISOR_memory_op(XENMEM_add_to_physmap_range, &xatp); >>>> + kfree(gpfns); >>>> + kfree(idxs); >>>> + kfree(errs); >>>> + if (rc) >>>> + return rc; >>> >>> Shouldn't we redo the mapping if the hypercall fails? >> Hmm, why? If it fails again when we redo the mapping, what should we do >> then? Redo again? > > Because the device MMIO region is left half mapped in DOM0 address space. > > After having another look to your patch, if an error occurs, the > notifier will still return NOTIFY_OK. This will lead to random data > abort when the driver is accessing the MMIO regions as the device will > be considered fully functional. > > However, even if the notifier return NOTIFY_BAD, the function device_add > doesn't care about the return value of blocking_notifier_call_chain. I > think this need to be fixed. > >> I think if it fails at the first time it will always fail no matter how >> many times we do. > > I was speaking about the mappings that succeeded. They will unlikely > fail during removal. If they ever fail you can just ignore the error. Ok, I see. I thought you mean that it needs to map the regions again. But what you really mean is undoing the mappings. Thanks, -- Shannon -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
