Messages in this thread | | | Date | Wed, 10 Apr 2024 12:41:34 -0300 | From | Jason Gunthorpe <> | Subject | Re: [PATCH 01/12] iommu/vt-d: Add cache tag assignment interface |
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On Mon, Mar 25, 2024 at 10:16:54AM +0800, Lu Baolu wrote: > Caching tag is a combination of tags used by the hardware to cache various > translations. Whenever a mapping in a domain is changed, the IOMMU driver > should invalidate the caches with the caching tags. The VT-d specification > describes caching tags in section 6.2.1, Tagging of Cached Translations. > > Add interface to assign caching tags to an IOMMU domain when attached to a > RID or PASID, and unassign caching tags when a domain is detached from a > RID or PASID. All caching tags are listed in the per-domain tag list and > are protected by a dedicated lock. > > In addition to the basic IOTLB and devTLB caching tag types, PARENT_IOTLB > and PARENT_DEVTLB tag types are also introduced. These tags are used for > caches that store translations for DMA accesses through a nested user > domain. They are affected by changes to mappings in the parent domain. > > Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> > --- > drivers/iommu/intel/iommu.h | 25 +++++ > drivers/iommu/intel/cache.c | 192 +++++++++++++++++++++++++++++++++++ > drivers/iommu/intel/iommu.c | 31 +++++- > drivers/iommu/intel/nested.c | 21 +++- > drivers/iommu/intel/svm.c | 12 ++- > drivers/iommu/intel/Makefile | 2 +- > 6 files changed, 274 insertions(+), 9 deletions(-) > create mode 100644 drivers/iommu/intel/cache.c > > diff --git a/drivers/iommu/intel/iommu.h b/drivers/iommu/intel/iommu.h > index 404d2476a877..e3723b7a0b31 100644 > --- a/drivers/iommu/intel/iommu.h > +++ b/drivers/iommu/intel/iommu.h > @@ -607,6 +607,9 @@ struct dmar_domain { > struct list_head devices; /* all devices' list */ > struct list_head dev_pasids; /* all attached pasids */ > > + spinlock_t cache_lock; /* Protect the cache tag list */ > + struct list_head cache_tags; /* Cache tag list */
That is quite a neat trick - though building a dedicated invalidation list duplicates data stored in the attached devices list?
You didn't try to make it RCU safe for invalidation?
> +struct cache_tag { > + struct list_head node; > + enum cache_tag_type type; > + struct intel_iommu *iommu; > + struct device *dev;
iommu and dev probably don't both need to be stored together. We have iommu_get_iommu_dev() now.. I suppose this is probably a union of the two pointers depending on tag. DEVTLB needs the dev and IOTLB needs the iommu.
> + u16 domain_id; > + ioasid_t pasid; > + int users;
unsigned int
> +static int __cache_tag_assign_parent_domain(struct dmar_domain *domain, u16 did, > + struct device *dev, ioasid_t pasid) > +{ > + struct device_domain_info *info = dev_iommu_priv_get(dev); > + int ret; > + > + ret = cache_tag_assign(domain, did, dev, pasid, CACHE_TAG_TYPE_PARENT_IOTLB); > + if (ret || !info->ats_enabled) > + return ret;
I'm not sure I understood the point of PARENT_IOTLB? I didn't see any different implementation?
Isn't this backwards though? Each domain should have a list of things to invalidate if the domain itself changes.
So the nesting parent should have a list of CHILD_DEVTLB's that need cleaning. That list is changed when the nesting domains are attached to something.
And a list of CHILD_IOTLBs, but the HW doesn't seem to need that?
Jason
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