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From: Christoph Hellwig <hch@lst.de>
To: Robin Murphy <robin.murphy@arm.com>
Cc: "Lendacky, Thomas" <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>,
	David Rientjes <rientjes@google.com>,
	Christoph Hellwig <hch@lst.de>
Subject: Re: [rfc] dma-mapping: preallocate unencrypted DMA atomic pool
Date: Tue, 7 Jan 2020 11:54:58 +0100	[thread overview]
Message-ID: <20200107105458.GA3139@lst.de> (raw)
In-Reply-To: <3213a6ac-5aad-62bc-bf95-fae8ba088b9e@arm.com>

On Mon, Jan 06, 2020 at 05:34:00PM +0000, Robin Murphy wrote:
> On 01/01/2020 1:54 am, David Rientjes via iommu wrote:
>> Christoph, Thomas, is something like this (without the diagnosic
>> information included in this patch) acceptable for these allocations?
>> Adding expansion support when the pool is half depleted wouldn't be *that*
>> hard.
>>
>> Or are there alternatives we should consider?  Thanks!
>
> Are there any platforms which require both non-cacheable remapping *and* 
> unencrypted remapping for distinct subsets of devices?
>
> If not (and I'm assuming there aren't, because otherwise this patch is 
> incomplete in covering only 2 of the 3 possible combinations), then 
> couldn't we keep things simpler by just attributing both properties to the 
> single "atomic pool" on the basis that one or the other will always be a 
> no-op? In other words, basically just tweaking the existing "!coherent" 
> tests to "!coherent || force_dma_unencrypted()" and doing 
> set_dma_unencrypted() unconditionally in atomic_pool_init().

I think that would make most sense.
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WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Robin Murphy <robin.murphy@arm.com>
Cc: David Rientjes <rientjes@google.com>,
	Christoph Hellwig <hch@lst.de>,
	"Lendacky, Thomas" <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>
Subject: Re: [rfc] dma-mapping: preallocate unencrypted DMA atomic pool
Date: Tue, 7 Jan 2020 11:54:58 +0100	[thread overview]
Message-ID: <20200107105458.GA3139@lst.de> (raw)
In-Reply-To: <3213a6ac-5aad-62bc-bf95-fae8ba088b9e@arm.com>

On Mon, Jan 06, 2020 at 05:34:00PM +0000, Robin Murphy wrote:
> On 01/01/2020 1:54 am, David Rientjes via iommu wrote:
>> Christoph, Thomas, is something like this (without the diagnosic
>> information included in this patch) acceptable for these allocations?
>> Adding expansion support when the pool is half depleted wouldn't be *that*
>> hard.
>>
>> Or are there alternatives we should consider?  Thanks!
>
> Are there any platforms which require both non-cacheable remapping *and* 
> unencrypted remapping for distinct subsets of devices?
>
> If not (and I'm assuming there aren't, because otherwise this patch is 
> incomplete in covering only 2 of the 3 possible combinations), then 
> couldn't we keep things simpler by just attributing both properties to the 
> single "atomic pool" on the basis that one or the other will always be a 
> no-op? In other words, basically just tweaking the existing "!coherent" 
> tests to "!coherent || force_dma_unencrypted()" and doing 
> set_dma_unencrypted() unconditionally in atomic_pool_init().

I think that would make most sense.

  reply	other threads:[~2020-01-07 10:55 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 [this message]
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
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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