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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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11f5acce2f
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:
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|---|---|---|
| .. | ||
| copy-paste.h | ||
| eeh-powernv.c | ||
| idle.c | ||
| Kconfig | ||
| Makefile | ||
| memtrace.c | ||
| npu-dma.c | ||
| ocxl.c | ||
| opal-async.c | ||
| opal-call.c | ||
| opal-dump.c | ||
| opal-elog.c | ||
| opal-flash.c | ||
| opal-hmi.c | ||
| opal-imc.c | ||
| opal-irqchip.c | ||
| opal-kmsg.c | ||
| opal-lpc.c | ||
| opal-memory-errors.c | ||
| opal-msglog.c | ||
| opal-nvram.c | ||
| opal-power.c | ||
| opal-powercap.c | ||
| opal-prd.c | ||
| opal-psr.c | ||
| opal-rtc.c | ||
| opal-sensor-groups.c | ||
| opal-sensor.c | ||
| opal-sysparam.c | ||
| opal-tracepoints.c | ||
| opal-wrappers.S | ||
| opal-xscom.c | ||
| opal.c | ||
| pci-cxl.c | ||
| pci-ioda-tce.c | ||
| pci-ioda.c | ||
| pci.c | ||
| pci.h | ||
| powernv.h | ||
| rng.c | ||
| setup.c | ||
| smp.c | ||
| subcore-asm.S | ||
| subcore.c | ||
| subcore.h | ||
| vas-debug.c | ||
| vas-trace.h | ||
| vas-window.c | ||
| vas.c | ||
| vas.h | ||