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