linux-kernel - RE: [PATCH] dma-direct: use the correct size for dma_set

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Date:   Thu, 23 Jun 2022 07:00:58 +0000
From:   Dexuan Cui <decui@...rosoft.com>
To:     Christoph Hellwig <hch@....de>
CC:     "m.szyprowski@...sung.com" <m.szyprowski@...sung.com>,
        "robin.murphy@....com" <robin.murphy@....com>,
        "iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-hyperv@...r.kernel.org" <linux-hyperv@...r.kernel.org>,
        "Michael Kelley (LINUX)" <mikelley@...rosoft.com>,
        Andrea Parri <Andrea.Parri@...rosoft.com>,
        Tianyu Lan <Tianyu.Lan@...rosoft.com>
Subject: RE: [PATCH] dma-direct: use the correct size for dma_set_encrypted()

> From: Christoph Hellwig <hch@....de>
> Sent: Wednesday, June 22, 2022 10:44 PM
> To: Dexuan Cui <decui@...rosoft.com>
>  ...
> On Wed, Jun 22, 2022 at 12:14:24PM -0700, Dexuan Cui wrote:
> > The third parameter of dma_set_encrypted() is a size in bytes rather than
> > the number of pages.
> >
> > Fixes: 4d0564785bb0 ("dma-direct: factor out dma_set_{de,en}crypted
> helpers")
> > Signed-off-by: Dexuan Cui <decui@...rosoft.com>
> 
> see:
> 
> commit 4a37f3dd9a83186cb88d44808ab35b78375082c9 (tag:
> dma-mapping-5.19-2022-05-25)
> Author: Robin Murphy <robin.murphy@....com>
> Date:   Fri May 20 18:10:13 2022 +0100
> 
>     dma-direct: don't over-decrypt memory

It looks like commit 4a37f3dd9a831 fixed a different issue?

Here my patch is for the latest mainline:

In dma_direct_alloc()'s error handling path, we pass 'size' to dma_set_encrypted():
  out_encrypt_pages:
	  if (dma_set_encrypted(dev, page_address(page), size))

However, in dma_direct_free(), we pass ' 1 << page_order ' to dma_set_encrypted().
I think the ' 1 << page_order' is incorrect and it should be 'size' as well?

Thanks,
-- Dexuan