Re: [RFC PATCH 1/4] dma: Add DMA allocation preservation KHO ABI

On Mon, Jun 08, 2026 at 05:53:43PM +0000, Pranjal Shrivastava wrote:
>On Tue, May 05, 2026 at 12:27:34AM +0000, Samiullah Khawaja wrote:
>> The DMA allocations can be backed by a variety of allocators. Add KHO
>> ABI for the preservation of contiguous allocations that are done through
>> dma-direct.
>>
>> Signed-off-by: Samiullah Khawaja <[email protected]>
>> ---
>>  include/linux/kho/abi/dma_alloc.h | 30 ++++++++++++++++++++++++++++++
>>  1 file changed, 30 insertions(+)
>>  create mode 100644 include/linux/kho/abi/dma_alloc.h
>>
>> diff --git a/include/linux/kho/abi/dma_alloc.h b/include/linux/kho/abi/dma_alloc.h
>> new file mode 100644
>> index 000000000000..46e61db81abe
>> --- /dev/null
>> +++ b/include/linux/kho/abi/dma_alloc.h
>> @@ -0,0 +1,30 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +#ifndef _LINUX_KHO_ABI_DMA_ALLOC_H
>> +#define _LINUX_KHO_ABI_DMA_ALLOC_H
>> +
>> +#include <linux/types.h>
>> +
>> +/**
>> + * DOC: DMA Alloc ABI
>> + *
>> + * This header defines the structures used to serialize the state of DMA
>> + * allocations, done by device driver, across a Live Update.
>> + *
>> + * Only DMA allocations done through dma-direct that are contiguous and
>> + * allocated using alloc_page are supported.
>> + */
>> +
>> +/**
>> + * struct dma_alloc_ser - Serialized state of a single DMA allocation
>> + * @page_phys: Physical address of the preserved pages
>> + * @size: Size of the DMA allocation
>> + * @force_decrypted: Whether the memory is force decrypted in previous kernel
>> + */
>> +struct dma_alloc_ser {
>> +	u64 page_phys;
>> +	u64 size;
>> +	u8 force_decrypted;
>
>Should we also stope attrs in this ser state here? There might be flags
>like DMA_ATTR_NO_KERNEL_MAPPING which would need to be preserved across
>a kexec?
>

Agree, as replied on the other patch.
>> +	u8 padding[7];
>> +} __packed;
>> +
>> +#endif /* _LINUX_KHO_ABI_DMA_ALLOC_H */
>> --
>> 2.54.0.545.g6539524ca2-goog
>>
>
>Thanks,
>Praan

Thanks,
Sami