Messages in this thread | | | Date | Fri, 01 May 2015 14:01:17 +1000 | From | Alexey Kardashevskiy <> | Subject | Re: [PATCH kernel v9 26/32] powerpc/iommu: Add userspace view of TCE table |
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On 04/29/2015 04:31 PM, David Gibson wrote: > On Sat, Apr 25, 2015 at 10:14:50PM +1000, Alexey Kardashevskiy wrote: >> In order to support memory pre-registration, we need a way to track >> the use of every registered memory region and only allow unregistration >> if a region is not in use anymore. So we need a way to tell from what >> region the just cleared TCE was from. >> >> This adds a userspace view of the TCE table into iommu_table struct. >> It contains userspace address, one per TCE entry. The table is only >> allocated when the ownership over an IOMMU group is taken which means >> it is only used from outside of the powernv code (such as VFIO). >> >> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> >> --- >> Changes: >> v9: >> * fixed code flow in error cases added in v8 >> >> v8: >> * added ENOMEM on failed vzalloc() >> --- >> arch/powerpc/include/asm/iommu.h | 6 ++++++ >> arch/powerpc/kernel/iommu.c | 18 ++++++++++++++++++ >> arch/powerpc/platforms/powernv/pci-ioda.c | 22 ++++++++++++++++++++-- >> 3 files changed, 44 insertions(+), 2 deletions(-) >> >> diff --git a/arch/powerpc/include/asm/iommu.h b/arch/powerpc/include/asm/iommu.h >> index 7694546..1472de3 100644 >> --- a/arch/powerpc/include/asm/iommu.h >> +++ b/arch/powerpc/include/asm/iommu.h >> @@ -111,9 +111,15 @@ struct iommu_table { >> unsigned long *it_map; /* A simple allocation bitmap for now */ >> unsigned long it_page_shift;/* table iommu page size */ >> struct iommu_table_group *it_table_group; >> + unsigned long *it_userspace; /* userspace view of the table */ > > A single unsigned long doesn't seem like enough.
Why single? This is an array.
> How do you know > which process's address space this address refers to?
It is a current task. Multiple userspaces cannot use the same container/tables.
>> struct iommu_table_ops *it_ops; >> }; >> >> +#define IOMMU_TABLE_USERSPACE_ENTRY(tbl, entry) \ >> + ((tbl)->it_userspace ? \ >> + &((tbl)->it_userspace[(entry) - (tbl)->it_offset]) : \ >> + NULL) >> + >> /* Pure 2^n version of get_order */ >> static inline __attribute_const__ >> int get_iommu_order(unsigned long size, struct iommu_table *tbl) >> diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c >> index 2eaba0c..74a3f52 100644 >> --- a/arch/powerpc/kernel/iommu.c >> +++ b/arch/powerpc/kernel/iommu.c >> @@ -38,6 +38,7 @@ >> #include <linux/pci.h> >> #include <linux/iommu.h> >> #include <linux/sched.h> >> +#include <linux/vmalloc.h> >> #include <asm/io.h> >> #include <asm/prom.h> >> #include <asm/iommu.h> >> @@ -739,6 +740,8 @@ void iommu_reset_table(struct iommu_table *tbl, const char *node_name) >> free_pages((unsigned long) tbl->it_map, order); >> } >> >> + WARN_ON(tbl->it_userspace); >> + >> memset(tbl, 0, sizeof(*tbl)); >> } >> >> @@ -1016,6 +1019,7 @@ int iommu_take_ownership(struct iommu_table *tbl) >> { >> unsigned long flags, i, sz = (tbl->it_size + 7) >> 3; >> int ret = 0; >> + unsigned long *uas; >> >> /* >> * VFIO does not control TCE entries allocation and the guest >> @@ -1027,6 +1031,10 @@ int iommu_take_ownership(struct iommu_table *tbl) >> if (!tbl->it_ops->exchange) >> return -EINVAL; >> >> + uas = vzalloc(sizeof(*uas) * tbl->it_size); >> + if (!uas) >> + return -ENOMEM; >> + >> spin_lock_irqsave(&tbl->large_pool.lock, flags); >> for (i = 0; i < tbl->nr_pools; i++) >> spin_lock(&tbl->pools[i].lock); >> @@ -1044,6 +1052,13 @@ int iommu_take_ownership(struct iommu_table *tbl) >> memset(tbl->it_map, 0xff, sz); >> } >> >> + if (ret) { >> + vfree(uas); >> + } else { >> + BUG_ON(tbl->it_userspace); >> + tbl->it_userspace = uas; >> + } >> + >> for (i = 0; i < tbl->nr_pools; i++) >> spin_unlock(&tbl->pools[i].lock); >> spin_unlock_irqrestore(&tbl->large_pool.lock, flags); >> @@ -1056,6 +1071,9 @@ void iommu_release_ownership(struct iommu_table *tbl) >> { >> unsigned long flags, i, sz = (tbl->it_size + 7) >> 3; >> >> + vfree(tbl->it_userspace); >> + tbl->it_userspace = NULL; >> + >> spin_lock_irqsave(&tbl->large_pool.lock, flags); >> for (i = 0; i < tbl->nr_pools; i++) >> spin_lock(&tbl->pools[i].lock); >> diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c >> index 45bc131..e0be556 100644 >> --- a/arch/powerpc/platforms/powernv/pci-ioda.c >> +++ b/arch/powerpc/platforms/powernv/pci-ioda.c >> @@ -25,6 +25,7 @@ >> #include <linux/memblock.h> >> #include <linux/iommu.h> >> #include <linux/sizes.h> >> +#include <linux/vmalloc.h> >> >> #include <asm/sections.h> >> #include <asm/io.h> >> @@ -1827,6 +1828,14 @@ static void pnv_ioda2_tce_free(struct iommu_table *tbl, long index, >> pnv_pci_ioda2_tce_invalidate(tbl, index, npages, false); >> } >> >> +void pnv_pci_ioda2_free_table(struct iommu_table *tbl) >> +{ >> + vfree(tbl->it_userspace); >> + tbl->it_userspace = NULL; >> + >> + pnv_pci_free_table(tbl); >> +} >> + >> static struct iommu_table_ops pnv_ioda2_iommu_ops = { >> .set = pnv_ioda2_tce_build, >> #ifdef CONFIG_IOMMU_API >> @@ -1834,7 +1843,7 @@ static struct iommu_table_ops pnv_ioda2_iommu_ops = { >> #endif >> .clear = pnv_ioda2_tce_free, >> .get = pnv_tce_get, >> - .free = pnv_pci_free_table, >> + .free = pnv_pci_ioda2_free_table, >> }; >> >> static void pnv_pci_ioda_setup_opal_tce_kill(struct pnv_phb *phb, >> @@ -2062,12 +2071,21 @@ static long pnv_pci_ioda2_create_table(struct iommu_table_group *table_group, >> int nid = pe->phb->hose->node; >> __u64 bus_offset = num ? pe->tce_bypass_base : 0; >> long ret; >> + unsigned long *uas, uas_cb = sizeof(*uas) * (window_size >> page_shift); >> + >> + uas = vzalloc(uas_cb); >> + if (!uas) >> + return -ENOMEM; > > I don't see why this is allocated both here as well as in > take_ownership.
Where else? The only alternative is vfio_iommu_spapr_tce but I really do not want to touch iommu_table fields there.
> Isn't this function used for core-kernel users of the > iommu as well, in which case it shouldn't need the it_userspace.
No. This is an iommu_table_group_ops callback which calls what the platform code calls (pnv_pci_create_table()) plus allocates this it_userspace thing. The callback is only called from VFIO.
> >> ret = pnv_pci_create_table(table_group, nid, bus_offset, page_shift, >> window_size, levels, tbl); >> - if (ret) >> + if (ret) { >> + vfree(uas); >> return ret; >> + } >> >> + BUG_ON(tbl->it_userspace); >> + tbl->it_userspace = uas; >> tbl->it_ops = &pnv_ioda2_iommu_ops; >> if (pe->tce_inval_reg) >> tbl->it_type |= (TCE_PCI_SWINV_CREATE | TCE_PCI_SWINV_FREE); >
-- Alexey
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