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From: Christoph Hellwig <hch@infradead.org>
To: "Alex Xu (Hello71)" <alex_y_xu@yahoo.ca>
Cc: Christoph Hellwig <hch@infradead.org>,
	iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
	regressions@lists.linux.dev
Subject: Re: "dma-mapping: remove CONFIG_DMA_REMAP" causes AMD SME boot fail
Date: Wed, 30 Mar 2022 21:08:43 -0700	[thread overview]
Message-ID: <YkUpSy4snmZ7E5xX@infradead.org> (raw)
In-Reply-To: <1648667469.u35o6clg82.none@localhost>

On Wed, Mar 30, 2022 at 03:17:20PM -0400, Alex Xu (Hello71) wrote:
> Excerpts from Christoph Hellwig's message of March 30, 2022 2:01 pm:
> > Can you try this patch, which is a bit of a hack?
> > 
> > diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c
> > index 50d209939c66c..61997c2ee0a17 100644
> > --- a/arch/x86/mm/mem_encrypt.c
> > +++ b/arch/x86/mm/mem_encrypt.c
> > @@ -28,7 +28,8 @@ bool force_dma_unencrypted(struct device *dev)
> >  	 * device does not support DMA to addresses that include the
> >  	 * encryption mask.
> >  	 */
> > -	if (cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT)) {
> > +	if (cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT) &&
> > +	    !get_dma_ops(dev)) {
> >  		u64 dma_enc_mask = DMA_BIT_MASK(__ffs64(sme_me_mask));
> >  		u64 dma_dev_mask = min_not_zero(dev->coherent_dma_mask,
> >  						dev->bus_dma_limit);
> > 
> 
> This seems to work for me.

Ok, I'll try to come up with a less hacky version and will start a
discussion with the AMD folks that know memory encryption better.
Thanks for the report and testing already!

  reply	other threads:[~2022-03-31  4:08 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1648659326.eabkokyuym.none.ref@localhost>
2022-03-30 17:51 ` "dma-mapping: remove CONFIG_DMA_REMAP" causes AMD SME boot fail Alex Xu (Hello71)
2022-03-30 17:55   ` Christoph Hellwig
2022-03-30 18:01   ` Christoph Hellwig
2022-03-30 19:17     ` Alex Xu (Hello71)
2022-03-31  4:08       ` Christoph Hellwig [this message]
2022-03-31  6:51   ` Thorsten Leemhuis
2022-04-15 17:58     ` "dma-mapping: remove CONFIG_DMA_REMAP" causes AMD SME boot fail #forregzbot Thorsten Leemhuis

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