Re: [PATCH v7 05/22] swiotlb: Preserve allocation virtual address for dynamic pools

On Wed, Jul 01, 2026 at 11:19:09AM +0530, Aneesh Kumar K.V (Arm) wrote:
> swiotlb_alloc_tlb() can allocate from the DMA atomic pool when a decrypted
> pool is needed from atomic context. With CONFIG_DMA_DIRECT_REMAP, the
> atomic pool is backed by remapped virtual addresses, which are not the same
> as the direct-map addresses returned by phys_to_virt().
> 
> swiotlb_init_io_tlb_pool() currently reconstructs the pool virtual address
> from the physical start address. For atomic-pool backed allocations this
> stores the wrong address in pool->vaddr. Later, swiotlb_free_tlb() passes
> that address to dma_free_from_pool(), which will fail to recognize the
> chunk
> 
> Pass the virtual address returned by the allocation path into
> swiotlb_init_io_tlb_pool(), and store that address in pool->vaddr. This
> keeps the pool free path using the same virtual address as the allocator.
> 
> Fixes: 79636caad361 ("swiotlb: if swiotlb is full, fall back to a transient memory pool")
> Tested-by: Michael Kelley <[email protected]>
> Tested-by: Mostafa Saleh <[email protected]>
> Reviewed-by: Petr Tesarik <[email protected]>
> Signed-off-by: Aneesh Kumar K.V (Arm) <[email protected]>
> ---
>  kernel/dma/swiotlb.c | 31 +++++++++++++++++++------------
>  1 file changed, 19 insertions(+), 12 deletions(-)

Reviewed-by: Jason Gunthorpe <[email protected]>

Jason