Re: [RFC] virtio: Use DMA MAP API for devices without an IOMMU

On Wed, Apr 18, 2018 at 07:20:10PM +0300, Michael S. Tsirkin wrote: > On Wed, Apr 18, 2018 at 08:47:10AM +0530, Anshuman Khandual wrote: > > On 04/15/2018 05:41 PM, Christoph Hellwig wrote: > > > On Fri, Apr 06, 2018 at 06:37:18PM +1000, Benjamin Herrenschmidt wrote: > > implemented as DMA

Re: [RFC] virtio: Use DMA MAP API for devices without an IOMMU

On Wed, Apr 18, 2018 at 07:20:10PM +0300, Michael S. Tsirkin wrote: > On Wed, Apr 18, 2018 at 08:47:10AM +0530, Anshuman Khandual wrote: > > On 04/15/2018 05:41 PM, Christoph Hellwig wrote: > > > On Fri, Apr 06, 2018 at 06:37:18PM +1000, Benjamin Herrenschmidt wrote: > > implemented as DMA

Re: [RFC] virtio: Use DMA MAP API for devices without an IOMMU

On Wed, Apr 18, 2018 at 08:47:10AM +0530, Anshuman Khandual wrote: > On 04/15/2018 05:41 PM, Christoph Hellwig wrote: > > On Fri, Apr 06, 2018 at 06:37:18PM +1000, Benjamin Herrenschmidt wrote: > implemented as DMA API which the virtio core understands. There is no > need for an IOMMU to

Re: [RFC] virtio: Use DMA MAP API for devices without an IOMMU

On Wed, Apr 18, 2018 at 08:47:10AM +0530, Anshuman Khandual wrote: > On 04/15/2018 05:41 PM, Christoph Hellwig wrote: > > On Fri, Apr 06, 2018 at 06:37:18PM +1000, Benjamin Herrenschmidt wrote: > implemented as DMA API which the virtio core understands. There is no > need for an IOMMU to

Re: [RFC] virtio: Use DMA MAP API for devices without an IOMMU

On 04/15/2018 05:41 PM, Christoph Hellwig wrote: > On Fri, Apr 06, 2018 at 06:37:18PM +1000, Benjamin Herrenschmidt wrote: implemented as DMA API which the virtio core understands. There is no need for an IOMMU to be involved for the device representation in this case IMHO. >>> >>>

Re: [RFC] virtio: Use DMA MAP API for devices without an IOMMU

On 04/15/2018 05:41 PM, Christoph Hellwig wrote: > On Fri, Apr 06, 2018 at 06:37:18PM +1000, Benjamin Herrenschmidt wrote: implemented as DMA API which the virtio core understands. There is no need for an IOMMU to be involved for the device representation in this case IMHO. >>> >>>

Re: [RFC] virtio: Use DMA MAP API for devices without an IOMMU

On Fri, Apr 06, 2018 at 06:37:18PM +1000, Benjamin Herrenschmidt wrote: > > > implemented as DMA API which the virtio core understands. There is no > > > need for an IOMMU to be involved for the device representation in this > > > case IMHO. > > > > This whole virtio translation issue is a mess.

Re: [RFC] virtio: Use DMA MAP API for devices without an IOMMU

On Fri, Apr 06, 2018 at 06:37:18PM +1000, Benjamin Herrenschmidt wrote: > > > implemented as DMA API which the virtio core understands. There is no > > > need for an IOMMU to be involved for the device representation in this > > > case IMHO. > > > > This whole virtio translation issue is a mess.

Re: [RFC] virtio: Use DMA MAP API for devices without an IOMMU

On Fri, 2018-04-06 at 00:16 -0700, Christoph Hellwig wrote: > On Fri, Apr 06, 2018 at 08:23:10AM +0530, Anshuman Khandual wrote: > > On 04/06/2018 02:48 AM, Benjamin Herrenschmidt wrote: > > > On Thu, 2018-04-05 at 21:34 +0300, Michael S. Tsirkin wrote: > > > > > In this specific case, because

Re: [RFC] virtio: Use DMA MAP API for devices without an IOMMU

On Fri, 2018-04-06 at 00:16 -0700, Christoph Hellwig wrote: > On Fri, Apr 06, 2018 at 08:23:10AM +0530, Anshuman Khandual wrote: > > On 04/06/2018 02:48 AM, Benjamin Herrenschmidt wrote: > > > On Thu, 2018-04-05 at 21:34 +0300, Michael S. Tsirkin wrote: > > > > > In this specific case, because

Re: [RFC] virtio: Use DMA MAP API for devices without an IOMMU

On Fri, Apr 06, 2018 at 08:23:10AM +0530, Anshuman Khandual wrote: > On 04/06/2018 02:48 AM, Benjamin Herrenschmidt wrote: > > On Thu, 2018-04-05 at 21:34 +0300, Michael S. Tsirkin wrote: > >>> In this specific case, because that would make qemu expect an iommu, > >>> and there isn't one. > >> >

Re: [RFC] virtio: Use DMA MAP API for devices without an IOMMU

On Fri, Apr 06, 2018 at 08:23:10AM +0530, Anshuman Khandual wrote: > On 04/06/2018 02:48 AM, Benjamin Herrenschmidt wrote: > > On Thu, 2018-04-05 at 21:34 +0300, Michael S. Tsirkin wrote: > >>> In this specific case, because that would make qemu expect an iommu, > >>> and there isn't one. > >> >

Re: [RFC] virtio: Use DMA MAP API for devices without an IOMMU

On 04/06/2018 02:48 AM, Benjamin Herrenschmidt wrote: > On Thu, 2018-04-05 at 21:34 +0300, Michael S. Tsirkin wrote: >>> In this specific case, because that would make qemu expect an iommu, >>> and there isn't one. >> >> >> I think that you can set iommu_platform in qemu without an iommu. > > No

Re: [RFC] virtio: Use DMA MAP API for devices without an IOMMU

On 04/06/2018 02:48 AM, Benjamin Herrenschmidt wrote: > On Thu, 2018-04-05 at 21:34 +0300, Michael S. Tsirkin wrote: >>> In this specific case, because that would make qemu expect an iommu, >>> and there isn't one. >> >> >> I think that you can set iommu_platform in qemu without an iommu. > > No

Re: [RFC] virtio: Use DMA MAP API for devices without an IOMMU

On Thu, 2018-04-05 at 21:34 +0300, Michael S. Tsirkin wrote: > > In this specific case, because that would make qemu expect an iommu, > > and there isn't one. > > > I think that you can set iommu_platform in qemu without an iommu. No I mean the platform has one but it's not desirable for it to

Re: [RFC] virtio: Use DMA MAP API for devices without an IOMMU

On Thu, 2018-04-05 at 21:34 +0300, Michael S. Tsirkin wrote: > > In this specific case, because that would make qemu expect an iommu, > > and there isn't one. > > > I think that you can set iommu_platform in qemu without an iommu. No I mean the platform has one but it's not desirable for it to

Re: [RFC] virtio: Use DMA MAP API for devices without an IOMMU

On Fri, Apr 06, 2018 at 01:09:43AM +1000, Benjamin Herrenschmidt wrote: > On Thu, 2018-04-05 at 17:54 +0300, Michael S. Tsirkin wrote: > > On Thu, Apr 05, 2018 at 08:09:30PM +0530, Anshuman Khandual wrote: > > > On 04/05/2018 04:26 PM, Anshuman Khandual wrote: > > > > There are certian platforms

Re: [RFC] virtio: Use DMA MAP API for devices without an IOMMU

On Fri, Apr 06, 2018 at 01:09:43AM +1000, Benjamin Herrenschmidt wrote: > On Thu, 2018-04-05 at 17:54 +0300, Michael S. Tsirkin wrote: > > On Thu, Apr 05, 2018 at 08:09:30PM +0530, Anshuman Khandual wrote: > > > On 04/05/2018 04:26 PM, Anshuman Khandual wrote: > > > > There are certian platforms

Re: [RFC] virtio: Use DMA MAP API for devices without an IOMMU

On Thu, 2018-04-05 at 17:54 +0300, Michael S. Tsirkin wrote: > On Thu, Apr 05, 2018 at 08:09:30PM +0530, Anshuman Khandual wrote: > > On 04/05/2018 04:26 PM, Anshuman Khandual wrote: > > > There are certian platforms which would like to use SWIOTLB based DMA API > > > for bouncing purpose without

Re: [RFC] virtio: Use DMA MAP API for devices without an IOMMU

On Thu, 2018-04-05 at 17:54 +0300, Michael S. Tsirkin wrote: > On Thu, Apr 05, 2018 at 08:09:30PM +0530, Anshuman Khandual wrote: > > On 04/05/2018 04:26 PM, Anshuman Khandual wrote: > > > There are certian platforms which would like to use SWIOTLB based DMA API > > > for bouncing purpose without

Re: [RFC] virtio: Use DMA MAP API for devices without an IOMMU

On Thu, Apr 05, 2018 at 08:09:30PM +0530, Anshuman Khandual wrote: > On 04/05/2018 04:26 PM, Anshuman Khandual wrote: > > There are certian platforms which would like to use SWIOTLB based DMA API > > for bouncing purpose without actually requiring an IOMMU back end. But the > > virtio core does

Re: [RFC] virtio: Use DMA MAP API for devices without an IOMMU

On Thu, Apr 05, 2018 at 08:09:30PM +0530, Anshuman Khandual wrote: > On 04/05/2018 04:26 PM, Anshuman Khandual wrote: > > There are certian platforms which would like to use SWIOTLB based DMA API > > for bouncing purpose without actually requiring an IOMMU back end. But the > > virtio core does

Re: [RFC] virtio: Use DMA MAP API for devices without an IOMMU

On 04/05/2018 04:26 PM, Anshuman Khandual wrote: > There are certian platforms which would like to use SWIOTLB based DMA API > for bouncing purpose without actually requiring an IOMMU back end. But the > virtio core does not allow such mechanism. Right now DMA MAP API is only > selected for

Re: [RFC] virtio: Use DMA MAP API for devices without an IOMMU

On 04/05/2018 04:26 PM, Anshuman Khandual wrote: > There are certian platforms which would like to use SWIOTLB based DMA API > for bouncing purpose without actually requiring an IOMMU back end. But the > virtio core does not allow such mechanism. Right now DMA MAP API is only > selected for

Re: [RFC] virtio: Use DMA MAP API for devices without an IOMMU

On 04/05/2018 04:44 PM, Balbir Singh wrote: > On Thu, Apr 5, 2018 at 8:56 PM, Anshuman Khandual > wrote: >> There are certian platforms which would like to use SWIOTLB based DMA API >> for bouncing purpose without actually requiring an IOMMU back end. But the >>

Re: [RFC] virtio: Use DMA MAP API for devices without an IOMMU

On 04/05/2018 04:44 PM, Balbir Singh wrote: > On Thu, Apr 5, 2018 at 8:56 PM, Anshuman Khandual > wrote: >> There are certian platforms which would like to use SWIOTLB based DMA API >> for bouncing purpose without actually requiring an IOMMU back end. But the >> virtio core does not allow such

Re: [RFC] virtio: Use DMA MAP API for devices without an IOMMU

On Thu, Apr 5, 2018 at 8:56 PM, Anshuman Khandual wrote: > There are certian platforms which would like to use SWIOTLB based DMA API > for bouncing purpose without actually requiring an IOMMU back end. But the > virtio core does not allow such mechanism. Right now DMA

Re: [RFC] virtio: Use DMA MAP API for devices without an IOMMU

On Thu, Apr 5, 2018 at 8:56 PM, Anshuman Khandual wrote: > There are certian platforms which would like to use SWIOTLB based DMA API > for bouncing purpose without actually requiring an IOMMU back end. But the > virtio core does not allow such mechanism. Right now DMA MAP API is only > selected

[RFC] virtio: Use DMA MAP API for devices without an IOMMU

There are certian platforms which would like to use SWIOTLB based DMA API for bouncing purpose without actually requiring an IOMMU back end. But the virtio core does not allow such mechanism. Right now DMA MAP API is only selected for devices which have an IOMMU and then the QEMU/host back end

[RFC] virtio: Use DMA MAP API for devices without an IOMMU

There are certian platforms which would like to use SWIOTLB based DMA API for bouncing purpose without actually requiring an IOMMU back end. But the virtio core does not allow such mechanism. Right now DMA MAP API is only selected for devices which have an IOMMU and then the QEMU/host back end