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Re: [Qemu-devel] [PATCH v5 08/17] vfio: Pass an Error object to vfio_con
From: |
Auger Eric |
Subject: |
Re: [Qemu-devel] [PATCH v5 08/17] vfio: Pass an Error object to vfio_connect_container |
Date: |
Mon, 10 Oct 2016 15:21:24 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.1.1 |
Hi Markus,
On 10/10/2016 14:36, Markus Armbruster wrote:
> Auger Eric <address@hidden> 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 <address@hidden> 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 <address@hidden>
>>>>>> Reviewed-by: Markus Armbruster <address@hidden>
>>>>>>
>>>>>> ---
>>>>>>
>>>>>> 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?
Thanks
Eric
>
- [Qemu-devel] [PATCH v5 03/17] vfio/pci: Pass an error object to vfio_populate_device, (continued)
- [Qemu-devel] [PATCH v5 03/17] vfio/pci: Pass an error object to vfio_populate_device, Eric Auger, 2016/10/06
- [Qemu-devel] [PATCH v5 05/17] vfio/pci: Pass an error object to vfio_intx_enable, Eric Auger, 2016/10/06
- [Qemu-devel] [PATCH v5 07/17] vfio/pci: Pass an error object to vfio_pci_igd_opregion_init, Eric Auger, 2016/10/06
- [Qemu-devel] [PATCH v5 08/17] vfio: Pass an Error object to vfio_connect_container, Eric Auger, 2016/10/06
- Re: [Qemu-devel] [PATCH v5 08/17] vfio: Pass an Error object to vfio_connect_container, Markus Armbruster, 2016/10/07
- Re: [Qemu-devel] [PATCH v5 08/17] vfio: Pass an Error object to vfio_connect_container, Auger Eric, 2016/10/07
- Re: [Qemu-devel] [PATCH v5 08/17] vfio: Pass an Error object to vfio_connect_container, Alexey Kardashevskiy, 2016/10/09
- Re: [Qemu-devel] [PATCH v5 08/17] vfio: Pass an Error object to vfio_connect_container, David Gibson, 2016/10/10
- Re: [Qemu-devel] [PATCH v5 08/17] vfio: Pass an Error object to vfio_connect_container, Auger Eric, 2016/10/10
- Re: [Qemu-devel] [PATCH v5 08/17] vfio: Pass an Error object to vfio_connect_container, Markus Armbruster, 2016/10/10
- Re: [Qemu-devel] [PATCH v5 08/17] vfio: Pass an Error object to vfio_connect_container,
Auger Eric <=
- Re: [Qemu-devel] [PATCH v5 08/17] vfio: Pass an Error object to vfio_connect_container, David Gibson, 2016/10/10
- Re: [Qemu-devel] [PATCH v5 08/17] vfio: Pass an Error object to vfio_connect_container, Markus Armbruster, 2016/10/10
- Re: [Qemu-devel] [PATCH v5 08/17] vfio: Pass an Error object to vfio_connect_container, David Gibson, 2016/10/10
[Qemu-devel] [PATCH v5 06/17] vfio/pci: Pass an error object to vfio_add_capabilities, Eric Auger, 2016/10/06
[Qemu-devel] [PATCH v5 10/17] vfio: Pass an error object to vfio_get_device, Eric Auger, 2016/10/06
[Qemu-devel] [PATCH v5 09/17] vfio: Pass an error object to vfio_get_group, Eric Auger, 2016/10/06
[Qemu-devel] [PATCH v5 12/17] vfio/platform: fix a wrong returned value in vfio_populate_device, Eric Auger, 2016/10/06
[Qemu-devel] [PATCH v5 11/17] vfio/platform: Pass an error object to vfio_populate_device, Eric Auger, 2016/10/06
[Qemu-devel] [PATCH v5 14/17] vfio/pci: Conversion to realize, Eric Auger, 2016/10/06
[Qemu-devel] [PATCH v5 13/17] vfio/platform: Pass an error object to vfio_base_device_init, Eric Auger, 2016/10/06