Re: [PATCH 1/4] dma-direct: factor out dma_set_{de,en}crypted helpers

[David Rientjes via iommu <iommu@lists.linux-foundation.org>]

On Tue, 19 Oct 2021, Christoph Hellwig wrote:

> Factor out helpers the make dealing with memory encryption a little less
> cumbersome.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  kernel/dma/direct.c | 55 +++++++++++++++++++++------------------------
>  1 file changed, 25 insertions(+), 30 deletions(-)
> 
> diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
> index 4c6c5e0635e34..96f02248e7fa2 100644
> --- a/kernel/dma/direct.c
> +++ b/kernel/dma/direct.c
> @@ -75,6 +75,20 @@ static bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size)
>  		min_not_zero(dev->coherent_dma_mask, dev->bus_dma_limit);
>  }
>  
> +static int dma_set_decrypted(struct device *dev, void *vaddr, size_t size)
> +{
> +	if (!force_dma_unencrypted(dev))
> +		return 0;
> +	return set_memory_decrypted((unsigned long)vaddr, 1 << get_order(size));
> +}
> +
> +static int dma_set_encrypted(struct device *dev, void *vaddr, size_t size)
> +{
> +	if (!force_dma_unencrypted(dev))
> +		return 0;
> +	return set_memory_encrypted((unsigned long)vaddr, 1 << get_order(size));
> +}
> +
>  static void __dma_direct_free_pages(struct device *dev, struct page *page,
>  				    size_t size)
>  {
> @@ -216,12 +230,7 @@ void *dma_direct_alloc(struct device *dev, size_t size,
>  				__builtin_return_address(0));
>  		if (!ret)
>  			goto out_free_pages;
> -		if (force_dma_unencrypted(dev)) {
> -			err = set_memory_decrypted((unsigned long)ret,
> -						   1 << get_order(size));
> -			if (err)
> -				goto out_free_pages;
> -		}
> +		err = dma_set_decrypted(dev, ret, size);

Should be

	if (dma_set_decrypted(dev, ret, size))
		goto out_free_pages;

?  Otherwise we ignore the value?

>  		memset(ret, 0, size);
>  		goto done;
>  	}
> @@ -238,13 +247,9 @@ void *dma_direct_alloc(struct device *dev, size_t size,
>  	}
>  
>  	ret = page_address(page);
> -	if (force_dma_unencrypted(dev)) {
> -		err = set_memory_decrypted((unsigned long)ret,
> -					   1 << get_order(size));
> -		if (err)
> -			goto out_free_pages;
> -	}
> -
> +	err = dma_set_decrypted(dev, ret, size);
> +	if (err)
> +		goto out_free_pages;
>  	memset(ret, 0, size);
>  
>  	if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED) &&
> @@ -259,13 +264,9 @@ void *dma_direct_alloc(struct device *dev, size_t size,
>  	return ret;
>  
>  out_encrypt_pages:
> -	if (force_dma_unencrypted(dev)) {
> -		err = set_memory_encrypted((unsigned long)page_address(page),
> -					   1 << get_order(size));
> -		/* If memory cannot be re-encrypted, it must be leaked */
> -		if (err)
> -			return NULL;
> -	}
> +	/* If memory cannot be re-encrypted, it must be leaked */
> +	if (dma_set_encrypted(dev, page_address(page), size))
> +		return NULL;
>  out_free_pages:
>  	__dma_direct_free_pages(dev, page, size);
>  	return NULL;
> @@ -304,8 +305,7 @@ void dma_direct_free(struct device *dev, size_t size,
>  	    dma_free_from_pool(dev, cpu_addr, PAGE_ALIGN(size)))
>  		return;
>  
> -	if (force_dma_unencrypted(dev))
> -		set_memory_encrypted((unsigned long)cpu_addr, 1 << page_order);
> +	dma_set_encrypted(dev, cpu_addr, 1 << page_order);
>  
>  	if (IS_ENABLED(CONFIG_DMA_REMAP) && is_vmalloc_addr(cpu_addr))
>  		vunmap(cpu_addr);
> @@ -341,11 +341,8 @@ struct page *dma_direct_alloc_pages(struct device *dev, size_t size,
>  	}
>  
>  	ret = page_address(page);
> -	if (force_dma_unencrypted(dev)) {
> -		if (set_memory_decrypted((unsigned long)ret,
> -				1 << get_order(size)))
> -			goto out_free_pages;
> -	}
> +	if (dma_set_decrypted(dev, ret, size))
> +		goto out_free_pages;
>  	memset(ret, 0, size);
>  	*dma_handle = phys_to_dma_direct(dev, page_to_phys(page));
>  	return page;
> @@ -366,9 +363,7 @@ void dma_direct_free_pages(struct device *dev, size_t size,
>  	    dma_free_from_pool(dev, vaddr, size))
>  		return;
>  
> -	if (force_dma_unencrypted(dev))
> -		set_memory_encrypted((unsigned long)vaddr, 1 << page_order);
> -
> +	dma_set_encrypted(dev, vaddr, 1 << page_order);
>  	__dma_direct_free_pages(dev, page, size);
>  }
>  
> -- 
> 2.30.2
> 
> 
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