linux-kernel - Re: 82fef0ad811f "x86/mm: unencrypted non-blocking DMA allocations use coherent pools" was Re: next-0519 on thinkpad x60: sound related? window manager crash

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Message-Id: <1591582140.kcn3hpk42g.none@localhost>
Date:   Sun, 07 Jun 2020 22:13:42 -0400
From:   "Alex Xu (Hello71)" <alex_y_xu@...oo.ca>
To:     David Rientjes <rientjes@...gle.com>
Cc:     alsa-devel@...a-project.org, bp@...en8.de, hch@...radead.org,
        hch@....de, hpa@...or.com, linux-kernel@...r.kernel.org,
        mingo@...hat.com, Pavel Machek <pavel@....cz>, perex@...ex.cz,
        tglx@...utronix.de, tiwai@...e.com, x86@...nel.org
Subject: Re: 82fef0ad811f "x86/mm: unencrypted non-blocking DMA allocations
 use coherent pools" was Re: next-0519 on thinkpad x60: sound related? window
 manager crash

Excerpts from David Rientjes's message of June 7, 2020 8:57 pm:
> Thanks for trying it out, Alex.  Would you mind sending your .config and 
> command line?  I assume either mem_encrypt=on or 
> CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT is enabled.
> 
> Could you also give this a try?
> 
> diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
> --- a/kernel/dma/direct.c
> +++ b/kernel/dma/direct.c
> @@ -99,10 +99,11 @@ static inline bool dma_should_alloc_from_pool(struct device *dev, gfp_t gfp,
>  static inline bool dma_should_free_from_pool(struct device *dev,
>  					     unsigned long attrs)
>  {
> -	if (IS_ENABLED(CONFIG_DMA_COHERENT_POOL))
> +	if (!IS_ENABLED(CONFIG_DMA_COHERENT_POOL))
> +		return false;
> +	if (force_dma_unencrypted(dev))
>  		return true;
> -	if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) &&
> -	    !force_dma_unencrypted(dev))
> +	if (attrs & DMA_ATTR_NO_KERNEL_MAPPING)
>  		return false;
>  	if (IS_ENABLED(CONFIG_DMA_DIRECT_REMAP))
>  		return true;
> 

This patch doesn't work for me either. It has since occurred to me that 
while I do have CONFIG_AMD_MEM_ENCYRPT=y, I have 
CONFIG_AMD_MEM_ENCRYPT_ACTIVE_BY_DEFAULT=n, because it was broken with 
amdgpu (unfortunately a downgrade from radeon in this respect). Tried it 
again just now and it looks like it's now able to enable KMS, but all it 
displays is serious-looking errors.

Sorry for not mentioning that earlier. I'll send you my .config and 
command line off-list.

Thanks,
Alex.