- 16 Jul, 2020 37 commits
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Nathan Lynch authored
pseries_update_drconf_memory() runs from a DT notifier in response to an update to the ibm,dynamic-memory property of the /ibm,dynamic-reconfiguration-memory node. This property is an older less compact format than the ibm,dynamic-memory-v2 property used in most currently supported firmwares. There has never been an equivalent function for the v2 property. pseries_update_drconf_memory() compares the 'assigned' flag for each LMB in the old vs new properties and adds or removes the block accordingly. However it appears to be of no actual utility: * Partition suspension and PRRNs are specified only to change LMBs' NUMA affinity information. This notifier should be a no-op for those scenarios since the assigned flags should not change. * The memory hotplug/DLPAR path has a hack which short-circuits execution of the notifier: dlpar_memory() ... rtas_hp_event = true; drmem_update_dt() of_update_property() pseries_memory_notifier() pseries_update_drconf_memory() if (rtas_hp_event) return; So this code only makes sense as a relic of the time when more of the DLPAR workflow took place in user space. I don't see a purpose for it now. Signed-off-by:Nathan Lynch <nathanl@linux.ibm.com> Signed-off-by:
Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200612051238.1007764-19-nathanl@linux.ibm.com
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Nathan Lynch authored
dlpar_cpu_readd() is unused now. Signed-off-by:
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Nathan Lynch authored
dlpar_memory() no longer has any callers which pass PSERIES_HP_ELOG_ACTION_READD. Remove this case and the corresponding unreachable code. Signed-off-by:
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Nathan Lynch authored
pseries_devicetree_update() is no longer called with PRRN_SCOPE. The purpose of prrn_update_node() was to remove and then add back a LMB whose NUMA assignment had changed. This has never been reliable, and this codepath has been default-disabled for several releases. Remove prrn_update_node(). Signed-off-by:
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Nathan Lynch authored
Since arch_update_cpu_topology() doesn't do anything on powerpc now, remove it and associated dead code. Signed-off-by:
Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by:
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Nathan Lynch authored
All users of this prrn_is_enabled() are gone; remove it. Signed-off-by:
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Nathan Lynch authored
prrn_is_enabled() always returns false/0, so handle_rtas_event() can be simplified and some dead code can be removed. Use machine_is() instead of #ifdef to run this code only on pseries, and add an informational ratelimited message that we are ignoring the events. PRRN events are relatively rare in normal operation and usually arise from operator-initiated actions such as a DPO (Dynamic Platform Optimizer) run. Eventually we do want to consume these events and update the device tree, but that needs more care to be safe vs LPM and DLPAR. Signed-off-by:
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Nathan Lynch authored
These APIs have become no-ops, so remove them and all call sites. Signed-off-by:
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Nathan Lynch authored
timed_topology_update is a no-op now, so remove it and all call sites. Signed-off-by:
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Nathan Lynch authored
Previous changes have removed the code which sets bits in cpu_associativity_changes_mask and thus it is never modifed at runtime. From this we can reason that numa_update_cpu_topology() always returns 0 without doing anything. Remove the body of numa_update_cpu_topology() and remove all code which becomes unreachable as a result. Signed-off-by:
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Nathan Lynch authored
These flags are always zero now; remove them and suitably adjust the remaining references to them. Signed-off-by:
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Nathan Lynch authored
Since vphn_enabled is always 0, we can remove the call to topology_schedule_update() and remove the code which becomes unreachable as a result. Signed-off-by:
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Nathan Lynch authored
Since vphn_enabled is always 0, we can stub out timed_topology_update() and remove the code which becomes unreachable. Signed-off-by:
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Nathan Lynch authored
Previous changes have made it so these flags are never changed; enforce this by making them const. Signed-off-by:
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Nathan Lynch authored
Since the topology_updates_enabled flag is now always false, remove it and the code which has become unreachable. This is the minimum change that prevents 'defined but unused' warnings emitted by the compiler after stubbing out the start/stop_topology_updates() functions. Signed-off-by:
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Nathan Lynch authored
Remove the /proc/powerpc/topology_updates interface and the topology_updates=on/off command line argument. The internal topology_updates_enabled flag remains for now, but always false. Signed-off-by:
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Nathan Lynch authored
Partition suspension, used for hibernation and migration, requires that the OS place all but one of the LPAR's processor threads into one of two states prior to calling the ibm,suspend-me RTAS function: * the architected offline state (via RTAS stop-self); or * the H_JOIN hcall, which does not return until the partition resumes execution Using H_CEDE as the offline mode, introduced by commit 3aa565f5 ("powerpc/pseries: Add hooks to put the CPU into an appropriate offline state"), means that any threads which are offline from Linux's point of view must be moved to one of those two states before a partition suspension can proceed. This was eventually addressed in commit 120496ac ("powerpc: Bring all threads online prior to migration/hibernation"), which added code to temporarily bring up any offline processor threads so they can call H_JOIN. Conceptually this is fine, but the implementation has had multiple races with cpu hotplug operations initiated from user space[1][2][3], the error handling is fragile, and it generates user-visible cpu hotplug events which is a lot of noise for a platform feature that's supposed to minimize disruption to workloads. With commit 3aa565f5 ("powerpc/pseries: Add hooks to put the CPU into an appropriate offline state") reverted, this code becomes unnecessary, so remove it. Since any offline CPUs now are truly offline from the platform's point of view, it is no longer necessary to bring up CPUs only to have them call H_JOIN and then go offline again upon resuming. Only active threads are required to call H_JOIN; stopped threads can be left alone. [1] commit a6717c01 ("powerpc/rtas: use device model APIs and serialization during LPM") [2] commit 9fb60305 ("powerpc/rtas: retry when cpu offline races with suspend/migration") [3] commit dfd718a2 ("powerpc/rtas: Fix a potential race between CPU-Offline & Migration") Fixes: 120496ac ("powerpc: Bring all threads online prior to migration/hibernation") Signed-off-by: -
Nathan Lynch authored
This effectively reverts commit 3aa565f5 ("powerpc/pseries: Add hooks to put the CPU into an appropriate offline state"), which added an offline mode for CPUs which uses the H_CEDE hcall instead of the architected stop-self RTAS function in order to facilitate "folding" of dedicated mode processors on PowerVM platforms to achieve energy savings. This has been the default offline mode since its introduction. There's nothing about stop-self that would prevent the hypervisor from achieving the energy savings available via H_CEDE, so the original premise of this change appears to be flawed. I also have encountered the claim that the transition to and from ceded state is much faster than stop-self/start-cpu. Certainly we would not want to use stop-self as an *idle* mode. That is what H_CEDE is for. However, this difference is insignificant in the context of Linux CPU hotplug, where the latency of an offline or online operation on current systems is on the order of 100ms, mainly attributable to all the various subsystems' cpuhp callbacks. The cede offline mode also prevents accurate accounting, as discussed before: https://lore.kernel.org/linuxppc-dev/1571740391-3251-1-git-send-email-ego@linux.vnet.ibm.com/ Unconditionally use stop-self to offline processor threads. This is the architected method for offlining CPUs on PAPR systems. The "cede_offline" boot parameter is rendered obsolete. Removing this code enables the removal of the partition suspend code which temporarily onlines all present CPUs. Fixes: 3aa565f5 ("powerpc/pseries: Add hooks to put the CPU into an appropriate offline state") Signed-off-by:
Gautham R. Shenoy <ego@linux.vnet.ibm.com> Signed-off-by:
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Nicholas Piggin authored
If both count cache and link stack are to be flushed, and can be flushed with the special bcctr, patch that in directly to the flush/branch nop site. Signed-off-by:
Nicholas Piggin <npiggin@gmail.com> Signed-off-by:
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Nicholas Piggin authored
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Nicholas Piggin authored
Branch cache flushing code patching has inter-dependencies on both the link stack and the count cache flushing state. To make the code clearer and to separate the link stack and count cache handling, split the "toggle" (setting up variables and printing enable/disable) from the code patching. Signed-off-by:
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Nicholas Piggin authored
Make the count-cache and link-stack messages look the same Signed-off-by:
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Nicholas Piggin authored
Prepare to allow for hardware link stack flushing by using the none/sw/hw type, same as the count cache state. Signed-off-by:
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Nicholas Piggin authored
The count cache flush mostly refers to both count cache and link stack flushing. As a first step to untangling these a bit, re-name the bits that apply to both. Signed-off-by:
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Nicholas Piggin authored
When a FP/VEC/VSX unavailable fault loads registers and enables the facility in the MSR, re-set the lazy restore counters to 1 rather than incrementing them so every fault gets the same number of restores before the next fault. This probably shouldn't be a practical change because if a lazy counter was non-zero then it should have been restored and would not cause a fault when userspace tries to access it. However the code and comment implies otherwise so that's misleading and unnecessary. Signed-off-by:
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Nicholas Piggin authored
Before returning to user, if there are missing FP/VEC/VSX bits from the user MSR then those registers had been saved and must be restored again before use. restore_math will decide whether to restore immediately, or skip the restore and let fp/vec/vsx unavailable faults demand load the registers. Each time restore_math restores one of the FP/VSX or VEC register sets is loaded, an 8-bit counter is incremented (load_fp and load_vec). When these wrap to zero, restore_math no longer restores that register set until after they are next demand faulted. It's quite usual for those counters to have different values, so if one wraps to zero and restore_math no longer restores its registers or user MSR bit but the other is not zero yet does not need to be restored (because the kernel is not frequently using the FPU), then restore_math will be called and it will also not return in the early exit check. This causes msr_check_and_set to test and set the MSR at every kernel exit despite having no work to do. This can cause workloads (e.g., a NULL syscall microbenchmark) to run fast for a time while both counters are non-zero, then slow down when one of the counters reaches zero, then speed up again after the second counter reaches zero. The cost is significant, about 10% slowdown on a NULL syscall benchmark, and the jittery behaviour is very undesirable. Fix this by having restore_math test all conditions first, and only update MSR if we will be loading registers. Signed-off-by:
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Nicholas Piggin authored
The TM test in restore_math added by commit dc16b553 ("powerpc: Always restore FPU/VEC/VSX if hardware transactional memory in use") is no longer necessary after commit a8318c13 ("powerpc/tm: Fix restoring FP/VMX facility incorrectly on interrupts"), which removed the cases where restore_math has to restore if TM is active. Signed-off-by:
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Aneesh Kumar K.V authored
With kernel now supporting new pmem flush/sync instructions, we can now enable the kernel to initialize the device. On P10 these devices would appear with a new compatible string. For PAPR device we have compatible "ibm,pmemory-v2" and for OF pmem device we have compatible "pmem-region-v2" Signed-off-by:
Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by:
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Aneesh Kumar K.V authored
nvdimm expect the flush routines to just mark the cache clean. The barrier that mark the store globally visible is done in nvdimm_flush(). Signed-off-by:
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Aneesh Kumar K.V authored
pmem on POWER10 can now use phwsync instead of hwsync to ensure all previous writes are architecturally visible for the platform buffer flush. Signed-off-by:
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Aneesh Kumar K.V authored
Architectures like ppc64 provide persistent memory specific barriers that will ensure that all stores for which the modifications are written to persistent storage by preceding dcbfps and dcbstps instructions have updated persistent storage before any data access or data transfer caused by subsequent instructions is initiated. This is in addition to the ordering done by wmb() Update nvdimm core such that architecture can use barriers other than wmb to ensure all previous writes are architecturally visible for the platform buffer flush. Signed-off-by:
Dan Williams <dan.j.williams@intel.com> Signed-off-by:
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Aneesh Kumar K.V authored
Start using dcbstps; phwsync; sequence for flushing persistent memory range. The new instructions are implemented as a variant of dcbf and hwsync and on P8 and P9 they will be executed as those instructions. We avoid using them on older hardware. This helps to avoid difficult to debug bugs. Signed-off-by:
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Aneesh Kumar K.V authored
POWER10 introduces two new variants of dcbf instructions (dcbstps and dcbfps) that can be used to write modified locations back to persistent storage. Additionally, POWER10 also introduce phwsync and plwsync which can be used to establish order of these writes to persistent storage. This patch exposes these instructions to the rest of the kernel. The existing dcbf and hwsync instructions in P8 and P9 are adequate to enable appropriate synchronization with OpenCAPI-hosted persistent storage. Hence the new instructions are added as a variant of the old ones that old hardware won't differentiate. Signed-off-by:
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Aneesh Kumar K.V authored
The PAPR based virtualized persistent memory devices are only supported on POWER9 and above. In the followup patch, the kernel will switch the persistent memory cache flush functions to use a new `dcbf` variant instruction. The new instructions even though added in ISA 3.1 works even on P8 and P9 because these are implemented as a variant of existing `dcbf` and `hwsync` and on P8 and P9 behaves as such. Considering these devices are only supported on P8 and above, update the driver to prevent a P7-compat guest from using persistent memory devices. We don't update of_pmem driver with the same condition, because, on bare-metal, the firmware enables pmem support only on P9 and above. There the kernel depends on OPAL firmware to restrict exposing persistent memory related device tree entries on older hardware. of_pmem.ko is written without any arch dependency and we don't want to add ppc64 specific cpu feature check in of_pmem driver. Signed-off-by:
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Nicholas Piggin authored
When platform doesn't support GTSE, let TLB invalidation requests for radix guests be off-loaded to the host using H_RPT_INVALIDATE hcall. [hcall wrapper, error path handling and renames] Signed-off-by:
Bharata B Rao <bharata@linux.ibm.com> Signed-off-by:
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Bharata B Rao authored
H_REGISTER_PROC_TBL asks for GTSE by default. GTSE flag bit should be set only when GTSE is supported. Signed-off-by:
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Bharata B Rao authored
Make GTSE an MMU feature and enable it by default for radix. However for guest, conditionally enable it if hypervisor supports it via OV5 vector. Let prom_init ask for radix GTSE only if the support exists. Having GTSE as an MMU feature will make it easy to enable radix without GTSE. Currently radix assumes GTSE is enabled by default. Signed-off-by:
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- 15 Jul, 2020 3 commits
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Christophe Leroy authored
On the same way as already done on PPC32, drop __get_datapage() function and use get_datapage inline macro instead. See commit ec0895f0 ("powerpc/vdso32: inline __get_datapage()") Signed-off-by:
Christophe Leroy <christophe.leroy@c-s.fr> Signed-off-by:
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Christophe Leroy authored
Instead of doing a __get_user() from the first and last location into a tmp var which won't be used, use fault_in_pages_readable() Signed-off-by:
Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by:
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Christophe Leroy authored
save_general_regs() which does special handling when i == PT_SOFTE. Rewrite it to minimise the specific part, especially the __put_user() and associated error handling is the same so make it common. Signed-off-by:
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