Re: [PATCH v6 07/11] arm64: Enforce bounce buffers for realm DMA

[Gavin Shan]

On 10/5/24 12:43 AM, Steven Price wrote:
> Within a realm guest it's not possible for a device emulated by the VMM
> to access arbitrary guest memory. So force the use of bounce buffers to
> ensure that the memory the emulated devices are accessing is in memory
> which is explicitly shared with the host.
>
> This adds a call to swiotlb_update_mem_attributes() which calls
> set_memory_decrypted() to ensure the bounce buffer memory is shared with
> the host. For non-realm guests or hosts this is a no-op.
>
> Reviewed-by: Catalin Marinas <catalin.marinas@xxxxxxx>
> Co-developed-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
> Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
> Signed-off-by: Steven Price <steven.price@xxxxxxx>
> ---
> v3: Simplify mem_init() by using a 'flags' variable.
> ---
>   arch/arm64/kernel/rsi.c |  1 +
>   arch/arm64/mm/init.c    | 10 +++++++++-
>   2 files changed, 10 insertions(+), 1 deletion(-)

Reviewed-by: Gavin Shan <gshan@xxxxxxxxxx>