On Wed, Mar 25, 2020 at 10:55:26AM -0700, Jacob Pan wrote: > Bare metal SVA allocates IOASIDs for native process addresses. This > should be separated from VM allocated IOASIDs thus under its own set. > > This patch creates a system IOASID set with its quota set to PID_MAX. > This is a reasonable default in that SVM capable devices can only bind > to limited user processes.
Yes realistically there won't be more than PID_MAX_DEFAULT=0x8000 bound address spaces. My machine uses a PID_MAX of 4 million though, so in theory more than 0x8000 processes may want a bond. On Arm the limit of shared contexts per VM is currently a little less than 0x10000 (which is the number of CPU ASIDs). But quotas are only necessary for VMs, when the host shares the PASID space with them (which isn't a use-case for Arm systems as far as I know, each VM gets its own PASID space). Could we have quota-free IOASID sets for the host? For the SMMU I'd like to allocate two sets, one SVA and one private for auxiliary domains, and I don't think giving either a quota makes much sense at the moment. There can be systems using only SVA and systems using only private PASIDs. I think it should be first-come-first-served until admins want a knob to define a policy themselves, based on cgroups for example. > Signed-off-by: Jacob Pan <[email protected]> > --- > drivers/iommu/intel-iommu.c | 8 +++++++- > drivers/iommu/ioasid.c | 9 +++++++++ > include/linux/ioasid.h | 9 +++++++++ > 3 files changed, 25 insertions(+), 1 deletion(-) > > diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c > index ec3fc121744a..af7a1ef7b31e 100644 > --- a/drivers/iommu/intel-iommu.c > +++ b/drivers/iommu/intel-iommu.c > @@ -3511,8 +3511,14 @@ static int __init init_dmars(void) > goto free_iommu; > > /* PASID is needed for scalable mode irrespective to SVM */ > - if (intel_iommu_sm) > + if (intel_iommu_sm) { > ioasid_install_capacity(intel_pasid_max_id); > + /* We should not run out of IOASIDs at boot */ > + if (ioasid_alloc_system_set(PID_MAX_DEFAULT)) { > + pr_err("Failed to enable host PASID allocator\n"); > + intel_iommu_sm = 0; > + } > + } > > /* > * for each drhd > diff --git a/drivers/iommu/ioasid.c b/drivers/iommu/ioasid.c > index 6265d2dbbced..9135af171a7c 100644 > --- a/drivers/iommu/ioasid.c > +++ b/drivers/iommu/ioasid.c > @@ -39,6 +39,9 @@ struct ioasid_data { > static ioasid_t ioasid_capacity; > static ioasid_t ioasid_capacity_avail; > > +int system_ioasid_sid; > +static DECLARE_IOASID_SET(system_ioasid); > + > /* System capacity can only be set once */ > void ioasid_install_capacity(ioasid_t total) > { > @@ -51,6 +54,12 @@ void ioasid_install_capacity(ioasid_t total) > } > EXPORT_SYMBOL_GPL(ioasid_install_capacity); > > +int ioasid_alloc_system_set(int quota) > +{ > + return ioasid_alloc_set(&system_ioasid, quota, &system_ioasid_sid); > +} > +EXPORT_SYMBOL_GPL(ioasid_alloc_system_set); I think this helper could stay in the VT-d driver for the moment. If the SMMU driver ever implements auxiliary domains it will use a private IOASID set, separate from the shared IOASID set managed by iommu-sva. Both could qualify as "system set". Thanks, Jean > + > /* > * 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 8c82d2625671..097b1cc043a3 100644 > --- a/include/linux/ioasid.h > +++ b/include/linux/ioasid.h > @@ -29,6 +29,9 @@ struct ioasid_allocator_ops { > void *pdata; > }; > > +/* Shared IOASID set for reserved for host system use */ > +extern int system_ioasid_sid; > + > #define DECLARE_IOASID_SET(name) struct ioasid_set name = { 0 } > > #if IS_ENABLED(CONFIG_IOASID) > @@ -41,6 +44,7 @@ int ioasid_register_allocator(struct ioasid_allocator_ops > *allocator); > void ioasid_unregister_allocator(struct ioasid_allocator_ops *allocator); > int ioasid_attach_data(ioasid_t ioasid, void *data); > void ioasid_install_capacity(ioasid_t total); > +int ioasid_alloc_system_set(int quota); > int ioasid_alloc_set(struct ioasid_set *token, ioasid_t quota, int *sid); > void ioasid_free_set(int sid, bool destroy_set); > int ioasid_find_sid(ioasid_t ioasid); > @@ -88,5 +92,10 @@ static inline void ioasid_install_capacity(ioasid_t total) > { > } > > +static inline int ioasid_alloc_system_set(int quota) > +{ > + return -ENOTSUPP; > +} > + > #endif /* CONFIG_IOASID */ > #endif /* __LINUX_IOASID_H */ > -- > 2.7.4 > _______________________________________________ iommu mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/iommu
