Messages in this thread | | | From | "Tian, Kevin" <> | Subject | RE: [PATCH v2 2/8] iommu: Add attach/detach_dev_pasid domain ops | Date | Tue, 15 Mar 2022 11:49:57 +0000 |
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> From: Jean-Philippe Brucker <jean-philippe@linaro.org> > Sent: Tuesday, March 15, 2022 7:27 PM > > On Mon, Mar 14, 2022 at 10:07:06PM -0700, Jacob Pan wrote: > > From: Lu Baolu <baolu.lu@linux.intel.com> > > > > An IOMMU domain represents an address space which can be attached by > > devices that perform DMA within a domain. However, for platforms with > > PASID capability the domain attachment needs be handled at device+PASID > > level. There can be multiple PASIDs within a device and multiple devices > > attached to a given domain. > > This patch introduces a new IOMMU op which support device, PASID, and > > IOMMU domain attachment. The immediate use case is for PASID capable > > devices to perform DMA under DMA APIs. > > > > Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> > > Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com> > > --- > > include/linux/iommu.h | 6 ++++++ > > 1 file changed, 6 insertions(+) > > > > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > > index 369f05c2a4e2..fde5b933dbe3 100644 > > --- a/include/linux/iommu.h > > +++ b/include/linux/iommu.h > > @@ -227,6 +227,8 @@ struct iommu_iotlb_gather { > > * @aux_get_pasid: get the pasid given an aux-domain > > * @sva_bind: Bind process address space to device > > * @sva_unbind: Unbind process address space from device > > + * @attach_dev_pasid: attach an iommu domain to a pasid of device > > + * @detach_dev_pasid: detach an iommu domain from a pasid of device > > Isn't that operation "assign a PASID to a domain" instead? In patch 5, > the domain is already attached to the device, so set_domain_pasid() might > be clearer and to the point. If the IOMMU driver did the allocation we > could also avoid patch 1.
iiuc this API can also work for future SIOV usage where each mdev attached to the domain has its own pasid. "assigning a PASID to a domain" sounds like going back to the previous aux domain approach which has one PASID per domain and that PASID is used on all devices attached to the aux domain...
> > If I understand correctly this series is not about a generic PASID API > that allows drivers to manage multiple DMA address spaces, because there > still doesn't seem to be any interest in that. It's about the specific > IDXD use-case, so let's focus on that. We can introduce a specialized call > such as (iommu|dma)_set_device_pasid(), which will be easy to consolidate > later into a more generic "dma_enable_pasid()" API if that ever seems > useful. > > Thanks, > Jean > > > * @sva_get_pasid: Get PASID associated to a SVA handle > > * @page_response: handle page request response > > * @cache_invalidate: invalidate translation caches > > @@ -296,6 +298,10 @@ struct iommu_ops { > > struct iommu_sva *(*sva_bind)(struct device *dev, struct mm_struct > *mm, > > void *drvdata); > > void (*sva_unbind)(struct iommu_sva *handle); > > + int (*attach_dev_pasid)(struct iommu_domain *domain, > > + struct device *dev, ioasid_t id); > > + void (*detach_dev_pasid)(struct iommu_domain *domain, > > + struct device *dev, ioasid_t id); > > u32 (*sva_get_pasid)(struct iommu_sva *handle); > > > > int (*page_response)(struct device *dev, > > -- > > 2.25.1 > >
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