All of lore.kernel.org
 help / color / mirror / Atom feed
From: Christoph Hellwig <hch@lst.de>
To: Lucas Stach <l.stach@pengutronix.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>,
	iommu@lists.linux-foundation.org, Christoph Hellwig <hch@lst.de>,
	linux-kernel@vger.kernel.org
Subject: Re: Regression due to d98849aff879 (dma-direct: handle DMA_ATTR_NO_KERNEL_MAPPING in common code)
Date: Tue, 6 Aug 2019 13:33:18 +0200	[thread overview]
Message-ID: <20190806113318.GA20215@lst.de> (raw)
In-Reply-To: <1565082809.2323.24.camel@pengutronix.de>

On Tue, Aug 06, 2019 at 11:13:29AM +0200, Lucas Stach wrote:
> Hi Christoph,
> 
> I just found a regression where my NVMe device is no longer able to set
> up its HMB.
> 
> After subject commit dma_direct_alloc_pages() is no longer initializing
> dma_handle properly when DMA_ATTR_NO_KERNEL_MAPPING is set, as the
> function is now returning too early.
> 
> Now this could easily be fixed by adding the phy_to_dma translation to
> the NO_KERNEL_MAPPING code path, but I'm not sure how this stuff
> interacts with the memory encryption stuff set up later in the
> function, so I guess this should be looked at by someone with more
> experience with this code than me.

There is not much we can do about the memory encryption case here,
as that requires a kernel address to mark the memory as unencrypted.

So the obvious trivial fix is probably the right one:


diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 59bdceea3737..c49120193309 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -135,6 +135,7 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size,
 		if (!PageHighMem(page))
 			arch_dma_prep_coherent(page, size);
 		/* return the page pointer as the opaque cookie */
+		*dma_handle = phys_to_dma(dev, page_to_phys(page));
 		return page;
 	}
 
_______________________________________________
iommu mailing list
iommu@lists.linux-foundation.org
https://lists.linuxfoundation.org/mailman/listinfo/iommu

WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Lucas Stach <l.stach@pengutronix.de>
Cc: Christoph Hellwig <hch@lst.de>,
	iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
	Tom Lendacky <thomas.lendacky@amd.com>
Subject: Re: Regression due to d98849aff879 (dma-direct: handle DMA_ATTR_NO_KERNEL_MAPPING in common code)
Date: Tue, 6 Aug 2019 13:33:18 +0200	[thread overview]
Message-ID: <20190806113318.GA20215@lst.de> (raw)
In-Reply-To: <1565082809.2323.24.camel@pengutronix.de>

On Tue, Aug 06, 2019 at 11:13:29AM +0200, Lucas Stach wrote:
> Hi Christoph,
> 
> I just found a regression where my NVMe device is no longer able to set
> up its HMB.
> 
> After subject commit dma_direct_alloc_pages() is no longer initializing
> dma_handle properly when DMA_ATTR_NO_KERNEL_MAPPING is set, as the
> function is now returning too early.
> 
> Now this could easily be fixed by adding the phy_to_dma translation to
> the NO_KERNEL_MAPPING code path, but I'm not sure how this stuff
> interacts with the memory encryption stuff set up later in the
> function, so I guess this should be looked at by someone with more
> experience with this code than me.

There is not much we can do about the memory encryption case here,
as that requires a kernel address to mark the memory as unencrypted.

So the obvious trivial fix is probably the right one:


diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 59bdceea3737..c49120193309 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -135,6 +135,7 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size,
 		if (!PageHighMem(page))
 			arch_dma_prep_coherent(page, size);
 		/* return the page pointer as the opaque cookie */
+		*dma_handle = phys_to_dma(dev, page_to_phys(page));
 		return page;
 	}
 

  reply	other threads:[~2019-08-06 11:33 UTC|newest]

Thread overview: 26+ 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  9:13 ` Lucas Stach
2019-08-06 11:33 ` Christoph Hellwig [this message]
2019-08-06 11:33   ` Christoph Hellwig
2019-08-06 12:20   ` Lucas Stach
2019-08-06 12:20     ` Lucas Stach
2019-08-06 13:38   ` Lendacky, Thomas
2019-08-06 13:38     ` Lendacky, Thomas
2019-08-06 14:04     ` Christoph Hellwig
2019-08-06 14:04       ` Christoph Hellwig
2019-08-06 14:06       ` Lucas Stach
2019-08-06 14:06         ` Lucas Stach
2019-08-06 14:18         ` Lendacky, Thomas
2019-08-06 14:18           ` Lendacky, Thomas
2019-08-06 15:46           ` Christoph Hellwig
2019-08-06 15:46             ` Christoph Hellwig
2019-08-06 15:59             ` Lendacky, Thomas
2019-08-06 15:59               ` Lendacky, Thomas
2019-08-06 16:07               ` Christoph Hellwig
2019-08-06 16:07                 ` Christoph Hellwig
2019-08-06 15:44         ` Christoph Hellwig
2019-08-06 15:44           ` Christoph Hellwig
2019-08-07 15:24           ` Lucas Stach
2019-08-07 15:24             ` Lucas Stach
2019-08-08  7:48             ` Christoph Hellwig
2019-08-08  7:48               ` Christoph Hellwig

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190806113318.GA20215@lst.de \
    --to=hch@lst.de \
    --cc=iommu@lists.linux-foundation.org \
    --cc=l.stach@pengutronix.de \
    --cc=linux-kernel@vger.kernel.org \
    --cc=thomas.lendacky@amd.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.