On Mon, Jul 24, 2017 at 02:07:52PM -0500, Brijesh Singh wrote:
> From: Tom Lendacky <thomas.lendacky@xxxxxxx>
>
> DMA access to memory mapped as encrypted while SEV is active can not be
> encrypted during device write or decrypted during device read.
Yeah, definitely rewrite that sentence.
> In order
> for DMA to properly work when SEV is active, the SWIOTLB bounce buffers
> must be used.
>
> Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx>
> Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx>
> ---
> arch/x86/mm/mem_encrypt.c | 86 +++++++++++++++++++++++++++++++++++++++++++++++
> lib/swiotlb.c | 5 +--
> 2 files changed, 89 insertions(+), 2 deletions
...
> @@ -202,6 +280,14 @@ void __init mem_encrypt_init(void)
> /* Call into SWIOTLB to update the SWIOTLB DMA buffers */
> swiotlb_update_mem_attributes();
>
> + /*
> + * With SEV, DMA operations cannot use encryption. New DMA ops
> + * are required in order to mark the DMA areas as decrypted or
> + * to use bounce buffers.
> + */
> + if (sev_active())
> + dma_ops = &sme_dma_ops;
Well, we do differentiate between SME and SEV and the check is
sev_active but the ops are called sme_dma_ops. Call them sev_dma_ops
instead for less confusion.
--
Regards/Gruss,
Boris.
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
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