On Mon, Oct 10, 2016 at 03:21:24PM +0200, Auger Eric wrote: > Hi Markus, > On 10/10/2016 14:36, Markus Armbruster wrote: > > Auger Eric <eric.au...@redhat.com> writes: > > > >> Hi, > >> > >> On 10/10/2016 07:34, David Gibson wrote: > >>> On Fri, Oct 07, 2016 at 09:36:09AM +0200, Auger Eric wrote: > >>>> Hi, > >>>> > >>>> On 07/10/2016 09:01, Markus Armbruster wrote: > >>>>> Eric Auger <eric.au...@redhat.com> writes: > >>>>> > >>>>>> The error is currently simply reported in vfio_get_group. Don't > >>>>>> bother too much with the prefix which will be handled at upper level, > >>>>>> later on. > >>>>>> > >>>>>> Also return an error value in case container->error is not 0 and > >>>>>> the container is teared down. > >>>>> > >>>>> "torn down", I think. > >>>> > >>>> Sure. I had a wrong feeling when writing this ... > >>>>> > >>>>> Is this a bug fix? See also below. > >>>>> > >>>>>> On vfio_spapr_remove_window failure, we also report an error whereas > >>>>>> it was silent before. > >>>>>> > >>>>>> Signed-off-by: Eric Auger <eric.au...@redhat.com> > >>>>>> Reviewed-by: Markus Armbruster <arm...@redhat.com> > >>>>>> > >>>>>> --- > >>>>>> > >>>>>> v4 -> v5: > >>>>>> - set ret to container->error > >>>>>> - mention error report on vfio_spapr_remove_window failure in the > >>>>>> commit > >>>>>> message > >>>>>> --- > >>>>>> hw/vfio/common.c | 40 +++++++++++++++++++++++++--------------- > >>>>>> 1 file changed, 25 insertions(+), 15 deletions(-) > >>>>>> > >>>>>> diff --git a/hw/vfio/common.c b/hw/vfio/common.c > >>>>>> index 29188a1..85a7759 100644 > >>>>>> --- a/hw/vfio/common.c > >>>>>> +++ b/hw/vfio/common.c > > [...] > >>>>>> @@ -1008,7 +1010,9 @@ static int vfio_connect_container(VFIOGroup > >>>>>> *group, AddressSpace *as) > > container = g_malloc0(sizeof(*container)); > > container->space = space; > > container->fd = fd; > > if (ioctl(fd, VFIO_CHECK_EXTENSION, VFIO_TYPE1_IOMMU) || > > ioctl(fd, VFIO_CHECK_EXTENSION, VFIO_TYPE1v2_IOMMU)) { > > [...] > > } else if (ioctl(fd, VFIO_CHECK_EXTENSION, VFIO_SPAPR_TCE_IOMMU) > > || > > ioctl(fd, VFIO_CHECK_EXTENSION, > > VFIO_SPAPR_TCE_v2_IOMMU)) { > > struct vfio_iommu_spapr_tce_info info; > > bool v2 = !!ioctl(fd, VFIO_CHECK_EXTENSION, > > VFIO_SPAPR_TCE_v2_IOMMU); > > > > ret = ioctl(group->fd, VFIO_GROUP_SET_CONTAINER, &fd); > > if (ret) { > > error_setg_errno(errp, errno, "failed to set group > > container"); > > ret = -errno; > > goto free_container_exit; > > } > > container->iommu_type = > > v2 ? VFIO_SPAPR_TCE_v2_IOMMU : VFIO_SPAPR_TCE_IOMMU; > > ret = ioctl(fd, VFIO_SET_IOMMU, container->iommu_type); > > if (ret) { > > error_setg_errno(errp, errno, "failed to set iommu for > > container"); > > ret = -errno; > > goto free_container_exit; > > } > > > > /* > > * The host kernel code implementing VFIO_IOMMU_DISABLE is > > called > > * when container fd is closed so we do not call it > > explicitly > > * in this file. > > */ > > if (!v2) { > > ret = ioctl(fd, VFIO_IOMMU_ENABLE); > > if (ret) { > > error_setg_errno(errp, errno, "failed to enable > > container"); > > ret = -errno; > > goto free_container_exit; > > } > > } else { > > container->prereg_listener = vfio_prereg_listener; > > > > memory_listener_register(&container->prereg_listener, > >>>>>> &address_space_memory); > >>>>>> if (container->error) { > >>>>> > >>>>> I tried to see where non-zero container->error comes from, but failed. > >>>>> Can you help? > >>>> > >>>> Added Alexey in CC > >>>> > >>>> It is set in vfio_prereg_listener_region_add (spapr.c) > >>>> There is a comment there saying: > >>>> /* > >>>> * On the initfn path, store the first error in the container so we > >>>> * can gracefully fail. Runtime, there's not much we can do other > >>>> * than throw a hardware error. > >>>> */ > >>>> 1) by the way I should also s/initfn/realize now. > >>>> 2) by gracefully fail I understand the error should be properly > >>>> cascaded. Also when looking at the other vfio_memory_listener > >>>> registration below, ret is set to container->error. > >>>> 3) I could use error_setg_errno ... > >>>> > >>>> David, Alexey, could you confirm we should set the returned value to the > >>>> container->error below? > >>> > >>> I think the right approach is to change container->error from an int > >>> to an Error *. As now, we stash the first error from the listener in > >>> there. > >>> > >>> realize() would check for a non-NULL error in the container after > >>> registering the listener, and if present, propagate it up to the > >>> caller. > >>> > >>>> > >>>> Thanks > >>>> > >>>> Eric > >>>> > >>>> > >>>>> > >>>>>> > >>>>>> memory_listener_unregister(&container->prereg_listener); > >>>>>> - error_report("vfio: RAM memory listener > >>>>>> initialization failed for container"); > >>>>>> + ret = container->error; > >> Thank you for your answers. OK to change container->error from an int > >> to an Error *. > >> > >> So I understand the fix just above is correct, ie. consider a non-NULL > >> container->error as an error that should be cascaded to the caller. > >> Currently I understand it is not since ret was left to 0. > > > > If whatever sets container->error now can provide more useful error > > information by setting an Error, then replacing VFIOContainer member int > > error by Error *err makes sense. Else, I recommend to keep it simple > > and stick to errno codes. > > > > My original question was about something else: I can't see what could > > have set container->error here. Have a look at the additional context I > > quoted above. Initially, container->error is zero. The ioctl()'s can't > > change it. That leaves memory_listener_register(). How can > > container->error be set? > My understanding is on > memory_listener_register(&container->prereg_listener, > &address_space_memory); > > you get the vfio_prereg_listener_region_add called which is likely to > set container->error with the returned value of > VFIO_IOMMU_SPAPR_REGISTER_MEMORY ioctl. > > Do I miss something?
That's correct. memory_listener_register() will call the registered listener on all existing memory regions. The listener we've registered can set container->error in some circumstances, so that's how it can be set here. -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson
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