| Message ID | 1484849955-1871-1-git-send-email-will.deacon@arm.com |
|---|---|
| Headers | show |
| Series | Implement SMMU passthrough using the default domain | expand |
Hi Will, >Hi all, > >A number of people have expressed interest in having the SMMU come up in >a passthrough configuration, and then allow subsequent translation for >things such as VFIO. Rather than do this in each SMMU driver, it's much >cleaner to allow the default domain to be configured to be something other >than DMA. > >This patch series implements a command-line option to configure the >default domain type. Currently, it supports "dma" and "identity" which >is sufficient for the passthrough use-case. > >Tested on an ARM fastmodel. > >All feedback welcome, > Thanks for this series. We had a case with the GPU. The GPU's iommu was setup by kernel and the GPU also does dynamic updates for on-the-fly switching between process pagetables. GPU driver was not using DMA domain and the GPU's firmware was always expecting to run out of contextbank '0' (although not correct) , which was not the case after the DMA domain was made default as '0' was getting allocated for DMA domain and there were concerns about reusing the DMA domain as well. Now with this series, looks there is an way out of that that can be tried. So should the default domain not be per device specific selectable ? Regards, Sricharan >Will > >--->8 > >Will Deacon (5): > iommu/arm-smmu: Restrict domain attributes to UNMANAGED domains > iommu/arm-smmu: Install bypass S2CRs for IOMMU_DOMAIN_IDENTITY domains > iommu/arm-smmu-v3: Install bypass STEs for IOMMU_DOMAIN_IDENTITY > domains > arm64: dma-mapping: Only swizzle DMA ops for IOMMU_DOMAIN_DMA > iommu: Allow default domain type to be set on the kernel command line > > arch/arm64/mm/dma-mapping.c | 17 ++++++++++++----- > drivers/iommu/arm-smmu-v3.c | 20 ++++++++++++++++++-- > drivers/iommu/arm-smmu.c | 26 +++++++++++++++++++++++--- > drivers/iommu/iommu.c | 19 +++++++++++++++++-- > 4 files changed, 70 insertions(+), 12 deletions(-) > >-- >2.1.4 > > >_______________________________________________ >linux-arm-kernel mailing list >linux-arm-kernel@lists.infradead.org >http://lists.infradead.org/mailman/listinfo/linux-arm-kernel _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
On Tue, Jan 24, 2017 at 08:42:23PM +0530, Sricharan wrote: > Thanks for this series. We had a case with the GPU. > The GPU's iommu was setup by kernel and the GPU > also does dynamic updates for on-the-fly switching between > process pagetables. GPU driver was not using DMA domain and > the GPU's firmware was always expecting to run out of contextbank > '0' (although not correct) , which was not the case after the DMA domain > was made default as '0' was getting allocated for DMA domain and > there were concerns about reusing the DMA domain as well. > Now with this series, looks there is an way out of that that can be tried. > > So should the default domain not be per device specific selectable ? Note that iommu-drivers can request direct-mapping for any given device on its initializtion. This is used on x86 for devices that need a 1-1 mapping for some reason. Also device drivers can use the iommu-api and assign their own domain to a device, which allows them to manage the dma address space on their own. Joerg _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
Hi all, A number of people have expressed interest in having the SMMU come up in a passthrough configuration, and then allow subsequent translation for things such as VFIO. Rather than do this in each SMMU driver, it's much cleaner to allow the default domain to be configured to be something other than DMA. This patch series implements a command-line option to configure the default domain type. Currently, it supports "dma" and "identity" which is sufficient for the passthrough use-case. Tested on an ARM fastmodel. All feedback welcome, Will --->8 Will Deacon (5): iommu/arm-smmu: Restrict domain attributes to UNMANAGED domains iommu/arm-smmu: Install bypass S2CRs for IOMMU_DOMAIN_IDENTITY domains iommu/arm-smmu-v3: Install bypass STEs for IOMMU_DOMAIN_IDENTITY domains arm64: dma-mapping: Only swizzle DMA ops for IOMMU_DOMAIN_DMA iommu: Allow default domain type to be set on the kernel command line arch/arm64/mm/dma-mapping.c | 17 ++++++++++++----- drivers/iommu/arm-smmu-v3.c | 20 ++++++++++++++++++-- drivers/iommu/arm-smmu.c | 26 +++++++++++++++++++++++--- drivers/iommu/iommu.c | 19 +++++++++++++++++-- 4 files changed, 70 insertions(+), 12 deletions(-) -- 2.1.4 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel