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From: Christoph Hellwig <hch@lst.de>
To: David Rientjes <rientjes@google.com>
Cc: Tom Lendacky <thomas.lendacky@amd.com>,
	"Singh, Brijesh" <brijesh.singh@amd.com>,
	"Grimm, Jon" <jon.grimm@amd.com>,
	baekhw@google.com,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>,
	Christoph Hellwig <hch@lst.de>
Subject: Re: [rfc 5/6] dma-direct: atomic allocations must come from unencrypted pools
Date: Thu, 5 Mar 2020 16:44:56 +0100	[thread overview]
Message-ID: <20200305154456.GC5332@lst.de> (raw)
In-Reply-To: <alpine.DEB.2.21.2003011538040.213582@chino.kir.corp.google.com>

On Sun, Mar 01, 2020 at 04:05:23PM -0800, David Rientjes wrote:
> When AMD memory encryption is enabled, all non-blocking DMA allocations
> must originate from the atomic pools depending on the device and the gfp
> mask of the allocation.
> 
> Keep all memory in these pools unencrypted.
> 
> Signed-off-by: David Rientjes <rientjes@google.com>
> ---
>  arch/x86/Kconfig    | 1 +
>  kernel/dma/direct.c | 9 ++++-----
>  kernel/dma/remap.c  | 2 ++
>  3 files changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -1523,6 +1523,7 @@ config X86_CPA_STATISTICS
>  config AMD_MEM_ENCRYPT
>  	bool "AMD Secure Memory Encryption (SME) support"
>  	depends on X86_64 && CPU_SUP_AMD
> +	select DMA_DIRECT_REMAP

I think we need to split the pool from remapping so that we don't drag
in the remap code for x86.

>  	if (IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
> -	    dma_alloc_need_uncached(dev, attrs) &&

We still need a check here for either uncached or memory encryption.

> @@ -141,6 +142,7 @@ static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size,
>  	if (!addr)
>  		goto free_page;
>  
> +	set_memory_decrypted((unsigned long)page_to_virt(page), nr_pages);

This probably warrants a comment.

Also I think the infrastructure changes should be split from the x86
wire up.
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WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: David Rientjes <rientjes@google.com>
Cc: Christoph Hellwig <hch@lst.de>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	"Singh, Brijesh" <brijesh.singh@amd.com>,
	"Grimm, Jon" <jon.grimm@amd.com>, Joerg Roedel <joro@8bytes.org>,
	baekhw@google.com,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>
Subject: Re: [rfc 5/6] dma-direct: atomic allocations must come from unencrypted pools
Date: Thu, 5 Mar 2020 16:44:56 +0100	[thread overview]
Message-ID: <20200305154456.GC5332@lst.de> (raw)
In-Reply-To: <alpine.DEB.2.21.2003011538040.213582@chino.kir.corp.google.com>

On Sun, Mar 01, 2020 at 04:05:23PM -0800, David Rientjes wrote:
> When AMD memory encryption is enabled, all non-blocking DMA allocations
> must originate from the atomic pools depending on the device and the gfp
> mask of the allocation.
> 
> Keep all memory in these pools unencrypted.
> 
> Signed-off-by: David Rientjes <rientjes@google.com>
> ---
>  arch/x86/Kconfig    | 1 +
>  kernel/dma/direct.c | 9 ++++-----
>  kernel/dma/remap.c  | 2 ++
>  3 files changed, 7 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -1523,6 +1523,7 @@ config X86_CPA_STATISTICS
>  config AMD_MEM_ENCRYPT
>  	bool "AMD Secure Memory Encryption (SME) support"
>  	depends on X86_64 && CPU_SUP_AMD
> +	select DMA_DIRECT_REMAP

I think we need to split the pool from remapping so that we don't drag
in the remap code for x86.

>  	if (IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
> -	    dma_alloc_need_uncached(dev, attrs) &&

We still need a check here for either uncached or memory encryption.

> @@ -141,6 +142,7 @@ static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size,
>  	if (!addr)
>  		goto free_page;
>  
> +	set_memory_decrypted((unsigned long)page_to_virt(page), nr_pages);

This probably warrants a comment.

Also I think the infrastructure changes should be split from the x86
wire up.

  reply	other threads:[~2020-03-05 15:45 UTC|newest]

Thread overview: 75+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-01  1:54 [rfc] dma-mapping: preallocate unencrypted DMA atomic pool David Rientjes via iommu
2020-01-01  1:54 ` David Rientjes
2020-01-06 17:34 ` Robin Murphy
2020-01-06 17:34   ` Robin Murphy
2020-01-07 10:54   ` Christoph Hellwig
2020-01-07 10:54     ` Christoph Hellwig
2020-01-07 19:57     ` David Rientjes via iommu
2020-01-07 19:57       ` David Rientjes
2020-01-09 14:31       ` Christoph Hellwig
2020-01-09 14:31         ` Christoph Hellwig
2020-01-09 18:58         ` David Rientjes via iommu
2020-01-09 18:58           ` David Rientjes
2020-01-17 15:28 ` Tom Lendacky
2020-01-17 15:28   ` Tom Lendacky
2020-02-28  9:27   ` David Rientjes via iommu
2020-02-28  9:27     ` David Rientjes
2020-03-02  0:05     ` [rfc 0/6] unencrypted atomic DMA pools with dynamic expansion David Rientjes via iommu
2020-03-02  0:05       ` David Rientjes
2020-03-02  0:05       ` [rfc 1/6] dma-mapping: pass device to atomic allocation functions David Rientjes via iommu
2020-03-02  0:05         ` David Rientjes
2020-03-02  0:05       ` [rfc 2/6] dma-remap: add additional atomic pools to map to gfp mask David Rientjes via iommu
2020-03-02  0:05         ` David Rientjes
2020-03-05 15:42         ` Christoph Hellwig
2020-03-05 15:42           ` Christoph Hellwig
2020-03-02  0:05       ` [rfc 3/6] dma-remap: wire up the atomic pools depending on " David Rientjes via iommu
2020-03-02  0:05         ` David Rientjes
2020-03-05 15:43         ` Christoph Hellwig
2020-03-05 15:43           ` Christoph Hellwig
2020-03-02  0:05       ` [rfc 4/6] dma-remap: dynamically expanding atomic pools David Rientjes via iommu
2020-03-02  0:05         ` David Rientjes
2020-03-03 22:29         ` David Rientjes via iommu
2020-03-03 22:29           ` David Rientjes
2020-03-02  0:05       ` [rfc 5/6] dma-direct: atomic allocations must come from unencrypted pools David Rientjes via iommu
2020-03-02  0:05         ` David Rientjes
2020-03-05 15:44         ` Christoph Hellwig [this message]
2020-03-05 15:44           ` Christoph Hellwig
2020-03-07  0:36           ` David Rientjes via iommu
2020-03-07  0:36             ` David Rientjes
2020-03-10 18:47             ` Christoph Hellwig
2020-03-10 18:47               ` Christoph Hellwig
2020-03-02  0:05       ` [rfc 6/6] dma-remap: double the default DMA coherent pool size David Rientjes via iommu
2020-03-02  0:05         ` David Rientjes
2020-03-05 15:45         ` Christoph Hellwig
2020-03-05 15:45           ` Christoph Hellwig
2020-04-08 21:21       ` [rfc v2 0/6] unencrypted atomic DMA pools with dynamic expansion David Rientjes via iommu
2020-04-08 21:21         ` David Rientjes
2020-04-08 21:21         ` [rfc v2 1/6] dma-remap: separate DMA atomic pools from direct remap code David Rientjes via iommu
2020-04-08 21:21           ` David Rientjes
2020-04-14  6:35           ` Christoph Hellwig
2020-04-14  6:35             ` Christoph Hellwig
2020-04-08 21:21         ` [rfc v2 2/6] dma-pool: add additional coherent pools to map to gfp mask David Rientjes via iommu
2020-04-08 21:21           ` David Rientjes
2020-04-08 21:21         ` [rfc v2 3/6] dma-pool: dynamically expanding atomic pools David Rientjes via iommu
2020-04-08 21:21           ` David Rientjes
2020-04-08 21:21         ` [rfc v2 4/6] dma-direct: atomic allocations must come from atomic coherent pools David Rientjes via iommu
2020-04-08 21:21           ` David Rientjes
2020-04-09 21:24           ` Tom Lendacky
2020-04-09 21:24             ` Tom Lendacky
2020-04-14 19:18             ` David Rientjes via iommu
2020-04-14 19:18               ` David Rientjes
2020-04-14  6:43           ` Christoph Hellwig
2020-04-14  6:43             ` Christoph Hellwig
2020-04-14 19:20             ` David Rientjes via iommu
2020-04-14 19:20               ` David Rientjes
2020-04-08 21:21         ` [rfc v2 5/6] x86/mm: unencrypted non-blocking DMA allocations use " David Rientjes via iommu
2020-04-08 21:21           ` David Rientjes
2020-04-08 21:21         ` [rfc v2 6/6] dma-pool: scale the default DMA coherent pool size with memory capacity David Rientjes via iommu
2020-04-08 21:21           ` David Rientjes
2020-04-10 14:55         ` [rfc v2 3/6] dma-pool: dynamically expanding atomic pools Hillf Danton
2020-04-10 19:37           ` David Rientjes via iommu
2020-04-10 19:37             ` David Rientjes
2020-04-14  6:44             ` Christoph Hellwig
2020-04-14  6:44               ` Christoph Hellwig
2020-04-14 19:23               ` David Rientjes via iommu
2020-04-14 19:23                 ` David Rientjes

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