linux-kernel - Re: [patch for-5.8 2/4] dma-direct: re-encrypt memory if dma_direct_alloc

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Message-ID: <20200615065625.GB21248@lst.de>
Date:   Mon, 15 Jun 2020 08:56:25 +0200
From:   Christoph Hellwig <hch@....de>
To:     David Rientjes <rientjes@...gle.com>
Cc:     Christoph Hellwig <hch@....de>,
        Thomas Lendacky <thomas.lendacky@....com>,
        Brijesh Singh <brijesh.singh@....com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Robin Murphy <robin.murphy@....com>,
        iommu@...ts.linux-foundation.org, linux-kernel@...r.kernel.org
Subject: Re: [patch for-5.8 2/4] dma-direct: re-encrypt memory if
 dma_direct_alloc_pages() fails

On Thu, Jun 11, 2020 at 12:20:29PM -0700, David Rientjes wrote:
> If arch_dma_set_uncached() fails after memory has been decrypted, it needs
> to be re-encrypted before freeing.
> 
> Fixes: fa7e2247c572 ("dma-direct: make uncached_kernel_address more
> general")
> Cc: stable@...r.kernel.org # 5.7
> Signed-off-by: David Rientjes <rientjes@...gle.com>

Note that this can't really happen in practice as
CONFIG_ARCH_HAS_DMA_SET_UNCACHED and memory encryption are mutally
exclusive in pracrie.  Still looks ok and useful otherwise.