From: Lu Baolu <baolu.lu@linux.intel.com>
To: Christoph Hellwig <hch@lst.de>
Cc: baolu.lu@linux.intel.com, David Woodhouse <dwmw2@infradead.org>,
Joerg Roedel <joro@8bytes.org>,
ashok.raj@intel.com, jacob.jun.pan@intel.com, alan.cox@intel.com,
kevin.tian@intel.com, mika.westerberg@linux.intel.com,
pengfei.xu@intel.com,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Marek Szyprowski <m.szyprowski@samsung.com>,
Robin Murphy <robin.murphy@arm.com>,
iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3 02/10] swiotlb: Factor out slot allocation and free
Date: Mon, 29 Apr 2019 13:10:17 +0800 [thread overview]
Message-ID: <93b3d627-782d-cae0-2175-77a5a8b3fe6e@linux.intel.com> (raw)
In-Reply-To: <20190426150433.GA19930@lst.de>
Hi Christoph,
On 4/26/19 11:04 PM, Christoph Hellwig wrote:
> On Thu, Apr 25, 2019 at 10:07:19AM +0800, Lu Baolu wrote:
>> This is not VT-d specific. It's just how generic IOMMU works.
>>
>> Normally, IOMMU works in paging mode. So if a driver issues DMA with
>> IOVA 0xAAAA0123, IOMMU can remap it with a physical address 0xBBBB0123.
>> But we should never expect IOMMU to remap 0xAAAA0123 with physical
>> address of 0xBBBB0000. That's the reason why I said that IOMMU will not
>> work there.
>
> Well, with the iommu it doesn't happen. With swiotlb it obviosuly
> can happen, so drivers are fine with it. Why would that suddenly
> become an issue when swiotlb is called from the iommu code?
>
I would say IOMMU is DMA remapping, not DMA engine. :-)
Best regards,
Lu Baolu
WARNING: multiple messages have this Message-ID (diff)
From: Lu Baolu <baolu.lu@linux.intel.com>
To: Christoph Hellwig <hch@lst.de>
Cc: kevin.tian@intel.com, mika.westerberg@linux.intel.com,
ashok.raj@intel.com,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
alan.cox@intel.com, Robin Murphy <robin.murphy@arm.com>,
iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
pengfei.xu@intel.com, jacob.jun.pan@intel.com,
David Woodhouse <dwmw2@infradead.org>
Subject: Re: [PATCH v3 02/10] swiotlb: Factor out slot allocation and free
Date: Mon, 29 Apr 2019 13:10:17 +0800 [thread overview]
Message-ID: <93b3d627-782d-cae0-2175-77a5a8b3fe6e@linux.intel.com> (raw)
Message-ID: <20190429051017._D5YTuRjhzfKEKNHcUVys6qIec9p8q3kTxDEEntel2w@z> (raw)
In-Reply-To: <20190426150433.GA19930@lst.de>
Hi Christoph,
On 4/26/19 11:04 PM, Christoph Hellwig wrote:
> On Thu, Apr 25, 2019 at 10:07:19AM +0800, Lu Baolu wrote:
>> This is not VT-d specific. It's just how generic IOMMU works.
>>
>> Normally, IOMMU works in paging mode. So if a driver issues DMA with
>> IOVA 0xAAAA0123, IOMMU can remap it with a physical address 0xBBBB0123.
>> But we should never expect IOMMU to remap 0xAAAA0123 with physical
>> address of 0xBBBB0000. That's the reason why I said that IOMMU will not
>> work there.
>
> Well, with the iommu it doesn't happen. With swiotlb it obviosuly
> can happen, so drivers are fine with it. Why would that suddenly
> become an issue when swiotlb is called from the iommu code?
>
I would say IOMMU is DMA remapping, not DMA engine. :-)
Best regards,
Lu Baolu
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next prev parent reply other threads:[~2019-04-29 5:10 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-21 1:17 [PATCH v3 00/10] iommu: Bounce page for untrusted devices Lu Baolu
2019-04-21 1:17 ` Lu Baolu
[not found] ` <20190421011719.14909-1-baolu.lu-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2019-04-21 1:17 ` [PATCH v3 01/10] iommu: Add helper to get minimal page size of domain Lu Baolu
2019-04-21 1:17 ` Lu Baolu
2019-04-29 10:55 ` Robin Murphy
2019-04-29 10:55 ` Robin Murphy
2019-04-30 0:40 ` Lu Baolu
2019-04-30 0:40 ` Lu Baolu
2019-04-21 1:17 ` [PATCH v3 02/10] swiotlb: Factor out slot allocation and free Lu Baolu
2019-04-21 1:17 ` Lu Baolu
2019-04-22 16:45 ` Christoph Hellwig
2019-04-22 16:45 ` Christoph Hellwig
2019-04-23 1:58 ` Lu Baolu
2019-04-23 1:58 ` Lu Baolu
2019-04-23 6:12 ` Christoph Hellwig
2019-04-23 6:12 ` Christoph Hellwig
2019-04-23 7:32 ` Lu Baolu
2019-04-23 7:32 ` Lu Baolu
2019-04-24 14:45 ` Christoph Hellwig
2019-04-24 14:45 ` Christoph Hellwig
[not found] ` <20190424144532.GA21480-jcswGhMUV9g@public.gmane.org>
2019-04-25 2:07 ` Lu Baolu
2019-04-25 2:07 ` Lu Baolu
2019-04-26 15:04 ` Christoph Hellwig
2019-04-26 15:04 ` Christoph Hellwig
2019-04-29 5:10 ` Lu Baolu [this message]
2019-04-29 5:10 ` Lu Baolu
2019-04-29 11:06 ` Robin Murphy
2019-04-29 11:06 ` Robin Murphy
2019-04-29 11:44 ` Christoph Hellwig
2019-04-29 11:44 ` Christoph Hellwig
2019-05-06 1:54 ` Lu Baolu
2019-05-13 7:05 ` Christoph Hellwig
2019-05-16 1:53 ` Lu Baolu
2019-04-30 2:02 ` Lu Baolu
2019-04-30 2:02 ` Lu Baolu
2019-04-30 9:53 ` Robin Murphy
2019-04-30 9:53 ` Robin Murphy
2019-05-02 1:47 ` Lu Baolu
2019-05-02 1:47 ` Lu Baolu
2019-04-21 1:17 ` [PATCH v3 03/10] swiotlb: Limit tlb address range inside slot pool Lu Baolu
2019-04-21 1:17 ` Lu Baolu
2019-04-21 1:17 ` [PATCH v3 04/10] swiotlb: Extend swiotlb to support page bounce Lu Baolu
2019-04-21 1:17 ` Lu Baolu
2019-04-21 1:17 ` [PATCH v3 05/10] iommu: Add bounce page APIs Lu Baolu
2019-04-21 1:17 ` Lu Baolu
2019-04-21 1:17 ` [PATCH v3 06/10] iommu/vt-d: Add trace events for domain map/unmap Lu Baolu
2019-04-21 1:17 ` Lu Baolu
2019-04-21 1:17 ` [PATCH v3 07/10] iommu/vt-d: Keep swiotlb on if bounce page is necessary Lu Baolu
2019-04-21 1:17 ` Lu Baolu
2019-04-22 16:47 ` Christoph Hellwig
2019-04-22 16:47 ` Christoph Hellwig
2019-04-23 2:00 ` Lu Baolu
2019-04-23 2:00 ` Lu Baolu
2019-04-21 1:17 ` [PATCH v3 08/10] iommu/vt-d: Check whether device requires bounce buffer Lu Baolu
2019-04-21 1:17 ` Lu Baolu
2019-04-22 16:47 ` Christoph Hellwig
2019-04-22 16:47 ` Christoph Hellwig
[not found] ` <20190422164755.GC31181-jcswGhMUV9g@public.gmane.org>
2019-04-23 2:03 ` Lu Baolu
2019-04-23 2:03 ` Lu Baolu
2019-04-23 6:08 ` Christoph Hellwig
2019-04-23 6:08 ` Christoph Hellwig
2019-04-23 7:35 ` Lu Baolu
2019-04-23 7:35 ` Lu Baolu
[not found] ` <e11489cf-87cc-a956-7c6c-ffdd26a4e3ec-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
2019-04-24 18:27 ` Konrad Rzeszutek Wilk
2019-04-24 18:27 ` Konrad Rzeszutek Wilk
2019-04-21 1:17 ` [PATCH v3 09/10] iommu/vt-d: Add dma sync ops for untrusted devices Lu Baolu
2019-04-21 1:17 ` Lu Baolu
2019-04-21 1:17 ` [PATCH v3 10/10] iommu/vt-d: Use bounce buffer " Lu Baolu
2019-04-21 1:17 ` Lu Baolu
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