From: "Lendacky, Thomas" <Thomas.Lendacky@amd.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Halil Pasic <pasic@linux.ibm.com>,
"iommu@lists.linux-foundation.org"
<iommu@lists.linux-foundation.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Lucas Stach <l.stach@pengutronix.de>
Subject: Re: Regression due to d98849aff879 (dma-direct: handle DMA_ATTR_NO_KERNEL_MAPPING in common code)
Date: Tue, 6 Aug 2019 15:59:40 +0000 [thread overview]
Message-ID: <5bd42e33-8077-ea23-a9f3-c575db4edada@amd.com> (raw)
In-Reply-To: <20190806154602.GB25050@lst.de>
On 8/6/19 10:46 AM, Christoph Hellwig wrote:
> On Tue, Aug 06, 2019 at 02:18:49PM +0000, Lendacky, Thomas wrote:
>> I think you need to keep everything inside the original if statement since
>> the caller is expecting a page pointer to be returned in this case and not
>> the page_address() which is returned when the DMA_ATTR_NO_KERNEL_MAPPING
>> is not present.
>
> DMA_ATTR_NO_KERNEL_MAPPING is defined to return an opaque cookie,
> which just happens to be a page pointer. So if we fix up the free side
> as pointed out by Lucas we should be fine.
As long as two different cookie types (page pointer for encrypted DMA
and virtual address returned from page_address() for unencrypted DMA)
is ok. I'm just not familiar with how the cookie is used in any other
functions, if at all.
Thanks,
Tom
>
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next prev parent reply other threads:[~2019-08-06 15:59 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-06 9:13 Regression due to d98849aff879 (dma-direct: handle DMA_ATTR_NO_KERNEL_MAPPING in common code) Lucas Stach
2019-08-06 11:33 ` Christoph Hellwig
2019-08-06 12:20 ` Lucas Stach
2019-08-06 13:38 ` Lendacky, Thomas
2019-08-06 14:04 ` Christoph Hellwig
2019-08-06 14:06 ` Lucas Stach
2019-08-06 14:18 ` Lendacky, Thomas
2019-08-06 15:46 ` Christoph Hellwig
2019-08-06 15:59 ` Lendacky, Thomas [this message]
2019-08-06 16:07 ` Christoph Hellwig
2019-08-06 15:44 ` Christoph Hellwig
2019-08-07 15:24 ` Lucas Stach
2019-08-08 7:48 ` Christoph Hellwig
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