[PATCH kernel] vfio/spapr_tce: Fix incorrect tce_iommu_group memory free

[Paul Mackerras]

On Mon, Aug 19, 2019 at 11:51:17AM +1000, Alexey Kardashevskiy wrote:
> The @tcegrp variable is used in 1) a loop over attached groups
> 2) it stores a pointer to a newly allocated tce_iommu_group if 1) found
> nothing. However the error handler does not distinguish how we got there
> and incorrectly releases memory for a found+incompatible group.
> 
> This fixes it by adding another error handling case.
> 
> Fixes: 0bd971676e68 ("powerpc/powernv/npu: Add compound IOMMU groups")
> Signed-off-by: Alexey Kardashevskiy <aik at ozlabs.ru>

Good catch.  This is potentially nasty since it is a double free.
Alex, are you going to take this, or would you prefer it goes via
Michael Ellerman's tree?

Reviewed-by: Paul Mackerras <paulus at ozlabs.org>