Re: [Qemu-devel] [PATCH v5 08/17] vfio: Pass an Error object to vfio_connect_container

[Alexey Kardashevskiy]

On 07/10/16 18:36, 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
>>> @@ -34,6 +34,7 @@
>>>  #include "qemu/range.h"
>>>  #include "sysemu/kvm.h"
>>>  #include "trace.h"
>>> +#include "qapi/error.h"
>>>  
>>>  struct vfio_group_head vfio_group_list =
>>>      QLIST_HEAD_INITIALIZER(vfio_group_list);
>>> @@ -900,7 +901,8 @@ static void vfio_put_address_space(VFIOAddressSpace 
>>> *space)
>>>      }
>>>  }
>>>  
>>> -static int vfio_connect_container(VFIOGroup *group, AddressSpace *as)
>>> +static int vfio_connect_container(VFIOGroup *group, AddressSpace *as,
>>> +                                  Error **errp)
>>>  {
>>>      VFIOContainer *container;
>>>      int ret, fd;
>>> @@ -918,15 +920,15 @@ static int vfio_connect_container(VFIOGroup *group, 
>>> AddressSpace *as)
>>>  
>>>      fd = qemu_open("/dev/vfio/vfio", O_RDWR);
>>>      if (fd < 0) {
>>> -        error_report("vfio: failed to open /dev/vfio/vfio: %m");
>>> +        error_setg_errno(errp, errno, "failed to open /dev/vfio/vfio");
>>>          ret = -errno;
>>>          goto put_space_exit;
>>>      }
>>>  
>>>      ret = ioctl(fd, VFIO_GET_API_VERSION);
>>>      if (ret != VFIO_API_VERSION) {
>>> -        error_report("vfio: supported vfio version: %d, "
>>> -                     "reported version: %d", VFIO_API_VERSION, ret);
>>> +        error_setg(errp, "supported vfio version: %d, "
>>> +                   "reported version: %d", VFIO_API_VERSION, ret);
>>>          ret = -EINVAL;
>>>          goto close_fd_exit;
>>>      }
>>> @@ -941,7 +943,7 @@ static int vfio_connect_container(VFIOGroup *group, 
>>> AddressSpace *as)
>>>  
>>>          ret = ioctl(group->fd, VFIO_GROUP_SET_CONTAINER, &fd);
>>>          if (ret) {
>>> -            error_report("vfio: failed to set group container: %m");
>>> +            error_setg_errno(errp, errno, "failed to set group container");
>>>              ret = -errno;
>>>              goto free_container_exit;
>>>          }
>>> @@ -949,7 +951,7 @@ static int vfio_connect_container(VFIOGroup *group, 
>>> AddressSpace *as)
>>>          container->iommu_type = v2 ? VFIO_TYPE1v2_IOMMU : VFIO_TYPE1_IOMMU;
>>>          ret = ioctl(fd, VFIO_SET_IOMMU, container->iommu_type);
>>>          if (ret) {
>>> -            error_report("vfio: failed to set iommu for container: %m");
>>> +            error_setg_errno(errp, errno, "failed to set iommu for 
>>> container");
>>>              ret = -errno;
>>>              goto free_container_exit;
>>>          }
>>> @@ -976,7 +978,7 @@ static int vfio_connect_container(VFIOGroup *group, 
>>> AddressSpace *as)
>>>  
>>>          ret = ioctl(group->fd, VFIO_GROUP_SET_CONTAINER, &fd);
>>>          if (ret) {
>>> -            error_report("vfio: failed to set group container: %m");
>>> +            error_setg_errno(errp, errno, "failed to set group container");
>>>              ret = -errno;
>>>              goto free_container_exit;
>>>          }
>>> @@ -984,7 +986,7 @@ static int vfio_connect_container(VFIOGroup *group, 
>>> AddressSpace *as)
>>>              v2 ? VFIO_SPAPR_TCE_v2_IOMMU : VFIO_SPAPR_TCE_IOMMU;
>>>          ret = ioctl(fd, VFIO_SET_IOMMU, container->iommu_type);
>>>          if (ret) {
>>> -            error_report("vfio: failed to set iommu for container: %m");
>>> +            error_setg_errno(errp, errno, "failed to set iommu for 
>>> container");
>>>              ret = -errno;
>>>              goto free_container_exit;
>>>          }
>>> @@ -997,7 +999,7 @@ static int vfio_connect_container(VFIOGroup *group, 
>>> AddressSpace *as)
>>>          if (!v2) {
>>>              ret = ioctl(fd, VFIO_IOMMU_ENABLE);
>>>              if (ret) {
>>> -                error_report("vfio: failed to enable container: %m");
>>> +                error_setg_errno(errp, errno, "failed to enable 
>>> container");
>>>                  ret = -errno;
>>>                  goto free_container_exit;
>>>              }
>>> @@ -1008,7 +1010,9 @@ static int vfio_connect_container(VFIOGroup *group, 
>>> AddressSpace *as)
>>>                                       &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 ...

Use on what Error* exactly? It is a listener, no return codes from there...


> David, Alexey, could you confirm we should set the returned value to the
> container->error below?

The hw/vfio/common.c's ret is -errno but the hw/vfio/spapr.c's ret is
ioctl()'s ret which is not a huge difference (as that specific ioctl() does
not return successful non-zero codes) but yes, I should have used -errno in
hw/vfio/spapr.c, not just ret.




> 
> Thanks
> 
> Eric
> 
> 
>>
>>>                  memory_listener_unregister(&container->prereg_listener);
>>> -                error_report("vfio: RAM memory listener initialization 
>>> failed for container");
>>> +                ret = container->error;
>>> +                error_setg(errp,
>>> +                    "RAM memory listener initialization failed for 
>>> container");
>>>                  goto free_container_exit;
>>>              }
>>>          }
>>> @@ -1016,7 +1020,8 @@ static int vfio_connect_container(VFIOGroup *group, 
>>> AddressSpace *as)
>>>          info.argsz = sizeof(info);
>>>          ret = ioctl(fd, VFIO_IOMMU_SPAPR_TCE_GET_INFO, &info);
>>>          if (ret) {
>>> -            error_report("vfio: VFIO_IOMMU_SPAPR_TCE_GET_INFO failed: %m");
>>> +            error_setg_errno(errp, errno,
>>> +                             "VFIO_IOMMU_SPAPR_TCE_GET_INFO failed");
>>>              ret = -errno;
>>>              if (v2) {
>>>                  memory_listener_unregister(&container->prereg_listener);
>>> @@ -1033,6 +1038,8 @@ static int vfio_connect_container(VFIOGroup *group, 
>>> AddressSpace *as)
>>>               */
>>>              ret = vfio_spapr_remove_window(container, 
>>> info.dma32_window_start);
>>>              if (ret) {
>>> +                error_setg_errno(errp, -ret,
>>> +                                 "failed to remove existing window");
>>>                  goto free_container_exit;
>>>              }
>>>          } else {
>>> @@ -1043,7 +1050,7 @@ static int vfio_connect_container(VFIOGroup *group, 
>>> AddressSpace *as)
>>>                                0x1000);
>>>          }
>>>      } else {
>>> -        error_report("vfio: No available IOMMU models");
>>> +        error_setg(errp, "No available IOMMU models");
>>>          ret = -EINVAL;
>>>          goto free_container_exit;
>>>      }
>>> @@ -1054,7 +1061,8 @@ static int vfio_connect_container(VFIOGroup *group, 
>>> AddressSpace *as)
>>>  
>>>      if (container->error) {
>>>          ret = container->error;
>>> -        error_report("vfio: memory listener initialization failed for 
>>> container");
>>> +        error_setg_errno(errp, -ret,
>>> +                         "memory listener initialization failed for 
>>> container");
>>>          goto listener_release_exit;
>>>      }
>>>  
>>> @@ -1120,6 +1128,7 @@ VFIOGroup *vfio_get_group(int groupid, AddressSpace 
>>> *as)
>>>      VFIOGroup *group;
>>>      char path[32];
>>>      struct vfio_group_status status = { .argsz = sizeof(status) };
>>> +    Error *err = NULL;
>>>  
>>>      QLIST_FOREACH(group, &vfio_group_list, next) {
>>>          if (group->groupid == groupid) {
>>> @@ -1158,8 +1167,9 @@ VFIOGroup *vfio_get_group(int groupid, AddressSpace 
>>> *as)
>>>      group->groupid = groupid;
>>>      QLIST_INIT(&group->device_list);
>>>  
>>> -    if (vfio_connect_container(group, as)) {
>>> -        error_report("vfio: failed to setup container for group %d", 
>>> groupid);
>>> +    if (vfio_connect_container(group, as, &err)) {
>>> +        error_reportf_err(err, "vfio: failed to setup container for group 
>>> %d",
>>> +                          groupid);
>>>          goto close_fd_exit;
>>>      }
>>


-- 
Alexey