Changing /etc/libvirt/qemu.conf make working things.
Uncomment user/group to work as root.

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   # The user for QEMU processes run by the system instance. It can be
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   # specified as a user name or as a user id. The qemu driver will try to
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   # parse this value first as a name and then, if the name doesn't exist,
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   # as a user id.
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   #
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   # Since a sequence of digits is a valid user name, a leading plus sign
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   # can be used to ensure that a user id will not be interpreted as a user
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   # name.
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   #
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    # Some examples of valid values are:
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    #
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    # user = "qemu" # A user named "qemu"
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    # user = "+0" # Super user (uid=0)
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    # user = "100" # A user named "100" or a user with uid=100
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    #
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    user = "root"
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    # The group for QEMU processes run by the system instance. It can be
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    # specified in a similar way to user.
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    group = "root"
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    # Whether libvirt should dynamically change file ownership
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    # to match the configured user/group above. Defaults to 1.
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    # Set to 0 to disable file ownership changes.
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    #dynamic_ownership = 1