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

[Auger Eric]

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 ...

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

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;
>>      }
>