Messages in this thread | | | Date | Wed, 1 Apr 2020 15:50:13 -0700 | From | Jacob Pan <> | Subject | Re: [PATCH 01/10] iommu/ioasid: Introduce system-wide capacity |
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Hi Jean,
On Wed, 1 Apr 2020 15:45:52 +0200 Jean-Philippe Brucker <jean-philippe@linaro.org> wrote:
> On Wed, Mar 25, 2020 at 10:55:22AM -0700, Jacob Pan wrote: > > IOASID is a limited system-wide resource that can be allocated at > > runtime. This limitation can be enumerated during boot. For > > example, on x86 platforms, PCI Process Address Space ID (PASID) > > allocation uses IOASID service. The number of supported PASID bits > > are enumerated by extended capability register as defined in the > > VT-d spec. > > > > This patch adds a helper to set the system capacity, it expected to > > be set during boot prior to any allocation request. > > This one-time setting is a bit awkward. Since multiple IOMMU drivers > may be loaded, this can't be a module_init() thing. And we generally > have multiple SMMU instances in the system. So we'd need to call > install_capacity() only for the first SMMU loaded with an arbitrary > 1<<20, even though each SMMU can support different numbers of PASID > bits. Furthermore, modules such as iommu-sva will want to initialize > their IOASID set at module_init(), which will happen before the SMMU > can set up the capacity, so ioasid_alloc_set() will return an error. > > How about hardcoding ioasid_capacity to 20 bits for now? It's the > PCIe limit and probably won't have to increase for a while. > Sound good. Default to 20 bits but can be adjusted if needed.
> Thanks, > Jean > > > > > Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com> > > --- > > drivers/iommu/ioasid.c | 15 +++++++++++++++ > > include/linux/ioasid.h | 5 ++++- > > 2 files changed, 19 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/iommu/ioasid.c b/drivers/iommu/ioasid.c > > index 0f8dd377aada..4026e52855b9 100644 > > --- a/drivers/iommu/ioasid.c > > +++ b/drivers/iommu/ioasid.c > > @@ -17,6 +17,21 @@ struct ioasid_data { > > struct rcu_head rcu; > > }; > > > > +static ioasid_t ioasid_capacity; > > +static ioasid_t ioasid_capacity_avail; > > + > > +/* System capacity can only be set once */ > > +void ioasid_install_capacity(ioasid_t total) > > +{ > > + if (ioasid_capacity) { > > + pr_warn("IOASID capacity already set at %d\n", > > ioasid_capacity); > > + return; > > + } > > + > > + ioasid_capacity = ioasid_capacity_avail = total; > > +} > > +EXPORT_SYMBOL_GPL(ioasid_install_capacity); > > + > > /* > > * struct ioasid_allocator_data - Internal data structure to hold > > information > > * about an allocator. There are two types of allocators: > > diff --git a/include/linux/ioasid.h b/include/linux/ioasid.h > > index 6f000d7a0ddc..9711fa0dc357 100644 > > --- a/include/linux/ioasid.h > > +++ b/include/linux/ioasid.h > > @@ -40,7 +40,7 @@ void *ioasid_find(struct ioasid_set *set, > > ioasid_t ioasid, int ioasid_register_allocator(struct > > ioasid_allocator_ops *allocator); void > > ioasid_unregister_allocator(struct ioasid_allocator_ops > > *allocator); int ioasid_set_data(ioasid_t ioasid, void *data); - > > +void ioasid_install_capacity(ioasid_t total); > > #else /* !CONFIG_IOASID */ > > static inline ioasid_t ioasid_alloc(struct ioasid_set *set, > > ioasid_t min, ioasid_t max, void *private) > > @@ -72,5 +72,8 @@ static inline int ioasid_set_data(ioasid_t > > ioasid, void *data) return -ENOTSUPP; > > } > > > > +static inline void ioasid_install_capacity(ioasid_t total) > > +{ > > +} > > #endif /* CONFIG_IOASID */ > > #endif /* __LINUX_IOASID_H */ > > -- > > 2.7.4 > >
[Jacob Pan]
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