From: Alexey Kardashevskiy aik@ozlabs.ru
[ Upstream commit 11f5acce2fa43b015a8120fa7620fa4efd0a2952 ]
We store 2 multilevel tables in iommu_table - one for the hardware and one with the corresponding userspace addresses. Before allocating the tables, the iommu_table_group_ops::get_table_size() hook returns the combined size of the two and VFIO SPAPR TCE IOMMU driver adjusts the locked_vm counter correctly. When the table is actually allocated, the amount of allocated memory is stored in iommu_table::it_allocated_size and used to decrement the locked_vm counter when we release the memory used by the table; .get_table_size() and .create_table() calculate it independently but the result is expected to be the same.
However the allocator does not add the userspace table size to .it_allocated_size so when we destroy the table because of VFIO PCI unplug (i.e. VFIO container is gone but the userspace keeps running), we decrement locked_vm by just a half of size of memory we are releasing.
To make things worse, since we enabled on-demand allocation of indirect levels, it_allocated_size contains only the amount of memory actually allocated at the table creation time which can just be a fraction. It is not a problem with incrementing locked_vm (as get_table_size() value is used) but it is with decrementing.
As the result, we leak locked_vm and may not be able to allocate more IOMMU tables after few iterations of hotplug/unplug.
This sets it_allocated_size in the pnv_pci_ioda2_ops::create_table() hook to what pnv_pci_ioda2_get_table_size() returns so from now on we have a single place which calculates the maximum memory a table can occupy. The original meaning of it_allocated_size is somewhat lost now though.
We do not ditch it_allocated_size whatsoever here and we do not call get_table_size() from vfio_iommu_spapr_tce.c when decrementing locked_vm as we may have multiple IOMMU groups per container and even though they all are supposed to have the same get_table_size() implementation, there is a small chance for failure or confusion.
Fixes: 090bad39b237 ("powerpc/powernv: Add indirect levels to it_userspace") Signed-off-by: Alexey Kardashevskiy aik@ozlabs.ru Reviewed-by: David Gibson david@gibson.dropbear.id.au Signed-off-by: Michael Ellerman mpe@ellerman.id.au Signed-off-by: Sasha Levin sashal@kernel.org --- arch/powerpc/platforms/powernv/pci-ioda-tce.c | 1 - arch/powerpc/platforms/powernv/pci-ioda.c | 7 ++++++- 2 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/arch/powerpc/platforms/powernv/pci-ioda-tce.c b/arch/powerpc/platforms/powernv/pci-ioda-tce.c index 7639b2168755..f5adb6b756f7 100644 --- a/arch/powerpc/platforms/powernv/pci-ioda-tce.c +++ b/arch/powerpc/platforms/powernv/pci-ioda-tce.c @@ -313,7 +313,6 @@ long pnv_pci_ioda2_table_alloc_pages(int nid, __u64 bus_offset, page_shift); tbl->it_level_size = 1ULL << (level_shift - 3); tbl->it_indirect_levels = levels - 1; - tbl->it_allocated_size = total_allocated; tbl->it_userspace = uas; tbl->it_nid = nid;
diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c index cde710297a4e..326ca6288bb1 100644 --- a/arch/powerpc/platforms/powernv/pci-ioda.c +++ b/arch/powerpc/platforms/powernv/pci-ioda.c @@ -2603,8 +2603,13 @@ static long pnv_pci_ioda2_create_table_userspace( int num, __u32 page_shift, __u64 window_size, __u32 levels, struct iommu_table **ptbl) { - return pnv_pci_ioda2_create_table(table_group, + long ret = pnv_pci_ioda2_create_table(table_group, num, page_shift, window_size, levels, true, ptbl); + + if (!ret) + (*ptbl)->it_allocated_size = pnv_pci_ioda2_get_table_size( + page_shift, window_size, levels); + return ret; }
static void pnv_ioda2_take_ownership(struct iommu_table_group *table_group)