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From: Robin Murphy <robin.murphy@arm.com>
To: Christoph Hellwig <hch@lst.de>
Cc: iommu@lists.linux-foundation.org, David Rientjes <rientjes@google.com>
Subject: Re: [PATCH 05/10] dma-direct: factor out a helper for DMA_ATTR_NO_KERNEL_MAPPING allocations
Date: Tue, 9 Nov 2021 14:39:21 +0000	[thread overview]
Message-ID: <986642d1-c3f2-6c8a-ad26-459355c47bb6@arm.com> (raw)
In-Reply-To: <20211109142532.GD23489@lst.de>

On 2021-11-09 14:25, Christoph Hellwig wrote:
> On Thu, Nov 04, 2021 at 12:36:16PM +0000, Robin Murphy wrote:
>>> -		*dma_handle = phys_to_dma_direct(dev, page_to_phys(page));
>>> -		/* return the page pointer as the opaque cookie */
>>> -		return page;
>>> -	}
>>> +	    !force_dma_unencrypted(dev) && !is_swiotlb_for_alloc(dev))
>>
>> Hmm, does force_dma_unencrypted() actually matter if the caller doesn't
>> want to access the buffer itself? Presumably any subsequent mmap() to
>> userspace would still do the right thing?
> 
> Well, force_dma_unencrypted is a bit misnamed I think.  It is mostly
> used to force bounce buffering for protected guest schemes.

Ah, that'll be what that small nagging doubt was at the time :)

Furthermore, implicit in the fact that the only comment I had was just 
musing on the existing code being moved, feel free to have a

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

for the refactor as-is.

Cheers,
Robin.
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  reply	other threads:[~2021-11-09 14:39 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-21  9:06 dma-direct fixes and cleanups v2 Christoph Hellwig
2021-10-21  9:06 ` [PATCH 01/10] dma-direct: factor out dma_set_{de,en}crypted helpers Christoph Hellwig
2021-11-04 12:35   ` Robin Murphy
2021-10-21  9:06 ` [PATCH 02/10] dma-direct: unmapped remapped pages when dma_set_decrypted Christoph Hellwig
2021-11-04 12:35   ` Robin Murphy
2021-11-09 14:10     ` Christoph Hellwig
2021-11-09 14:27       ` Robin Murphy
2021-10-21  9:06 ` [PATCH 03/10] dma-direct: leak memory that can't be re-encrypted Christoph Hellwig
2021-11-04 12:35   ` Robin Murphy
2021-11-09 14:19     ` Christoph Hellwig
2021-10-21  9:06 ` [PATCH 04/10] dma-direct: clean up the remapping checks in dma_direct_alloc Christoph Hellwig
2021-11-04 12:35   ` Robin Murphy
2021-11-09 14:23     ` Christoph Hellwig
2021-10-21  9:06 ` [PATCH 05/10] dma-direct: factor out a helper for DMA_ATTR_NO_KERNEL_MAPPING allocations Christoph Hellwig
2021-11-04 12:36   ` Robin Murphy
2021-11-09 14:25     ` Christoph Hellwig
2021-11-09 14:39       ` Robin Murphy [this message]
2021-10-21  9:06 ` [PATCH 06/10] dma-direct: refactor the !coherent checks in dma_direct_alloc Christoph Hellwig
2021-11-04 12:36   ` Robin Murphy
2021-11-09 14:27     ` Christoph Hellwig
2021-10-21  9:06 ` [PATCH 07/10] dma-direct: warn if there is no pool for force unencrypted allocations Christoph Hellwig
2021-11-04 12:36   ` Robin Murphy
2021-10-21  9:06 ` [PATCH 08/10] dma-direct: drop two CONFIG_DMA_RESTRICTED_POOL conditionals Christoph Hellwig
2021-11-04 12:37   ` Robin Murphy
2021-10-21  9:06 ` [PATCH 09/10] dma-direct: factor the swiotlb code out of __dma_direct_alloc_pages Christoph Hellwig
2021-11-04 12:37   ` Robin Murphy
2021-10-21  9:06 ` [PATCH 10/10] dma-direct: add a dma_direct_use_pool helper Christoph Hellwig
2021-11-04 12:37   ` Robin Murphy
2021-11-04  8:54 ` dma-direct fixes and cleanups v2 Christoph Hellwig

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