- 16 Jul, 2020 40 commits
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YueHaibing authored
commit e27e0a94 ("powerpc/xive: Remove xive_kexec_teardown_cpu()") left behind this, remove it. Signed-off-by:
YueHaibing <yuehaibing@huawei.com> Reviewed-by:
Greg Kurz <groug@kaod.org> Signed-off-by:
Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200715025040.33952-1-yuehaibing@huawei.com
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Sourabh Jain authored
When we enter into fadump crash path via system reset we fail to update the pstore. On the system reset path we first update the pstore then we go for fadump crash. But the problem here is when all the CPUs try to get the pstore lock to initiate the pstore write, only one CPUs will acquire the lock and proceed with the pstore write. Since it in NMI context CPUs that fail to get lock do not wait for their turn to write to the pstore and simply proceed with the next operation which is fadump crash. One of the CPU who proceeded with fadump crash path triggers the crash and does not wait for the CPU who gets the pstore lock to complete the pstore update. Timeline diagram to depicts the sequence of events that leads to an unsuccessful pstore update when we hit fadump crash path via system reset. 1 2 3 ... n CPU Threads | | | | | | | | Reached to -->|--->|---->| ----------->| system reset | | | | path | | | | | | | | Try to -->|--->|---->|------------>| acquire the | | | | pstore lock | | | | | | | | | | | | Got the -->| +->| | |<-+ pstore lock | | | | | |--> Didn't get the | --------------------------+ lock and moving | | | | ahead on fadump | | | | crash path | | | | Begins the -->| | | | process to | | | |<-- Got the chance to update the | | | | trigger the crash pstore | -> | | ... <- | | | | | | | | | | | | |<-- Triggers the | | | | | | crash | | | | | | ^ | | | | | | | Writing to -->| | | | | | | pstore | | | | | | | | | | ^ |__________________| | | CPU Relax | | | +-----------------------------------------+ | v Race: crash triggered before pstore update completes To avoid this race condition a barrier is added on crash_fadump path, it prevents the CPU to trigger the crash until all the online CPUs completes their task. A barrier is added to make sure all the secondary CPUs hit the crash_fadump function before we initiates the crash. A timeout is kept to ensure the primary CPU (one who initiates the crash) do not wait for secondary CPUs indefinitely. Signed-off-by:Sourabh Jain <sourabhjain@linux.ibm.com> Signed-off-by:
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Anton Blanchard authored
Generic code has a wrapper to implement cputime_to_nsecs() on top of cputime_to_usecs() but we can easily return the full nanosecond resolution directly. Signed-off-by:
Anton Blanchard <anton@ozlabs.org> Signed-off-by:
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Balamuruhan S authored
Lots of PPC_INST_* macros are used only ever in PPC_* macros, fold those PPC_INST_* into PPC_RAW_* to avoid using PPC_INST_* accidentally. Signed-off-by:
Balamuruhan S <bala24@linux.ibm.com> Tested-by:
Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Acked-by:
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Balamuruhan S authored
Wrap existing stringify macros to reuse raw instruction encoding macros that are newly added. Signed-off-by:
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Balamuruhan S authored
Move macro definitions of powerpc instructions from bpf_jit.h to ppc-opcode.h and adopt the users of the macros accordingly. `PPC_MR()` is defined twice in bpf_jit.h, remove the duplicate one. Signed-off-by:
Sandipan Das <sandipan@linux.ibm.com> Signed-off-by:
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Balamuruhan S authored
Remove duplicate macro definitions from bpf_jit.h and reuse the macros from ppc-opcode.h Signed-off-by:
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Balamuruhan S authored
Few ppc instructions are encoded in test_emulate_step.c, consolidate them and use it from ppc-opcode.h Signed-off-by:
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Balamuruhan S authored
Introduce PPC_RAW_* macros to have all the bare encoding of ppc instructions. Move `VSX_XX*()` and `TMRN()` macros up to reuse it. Signed-off-by:
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Kajol Jain authored
Patch here adds a cpumask attr to hv_24x7 pmu along with ABI documentation. Primary use to expose the cpumask is for the perf tool which has the capability to parse the driver sysfs folder and understand the cpumask file. Having cpumask file will reduce the number of perf command line parameters (will avoid "-C" option in the perf tool command line). It can also notify the user which is the current cpu used to retrieve the counter data. command:# cat /sys/devices/hv_24x7/interface/cpumask 0 Signed-off-by:
Kajol Jain <kjain@linux.ibm.com> Reviewed-by:
Madhavan Srinivasan <maddy@linux.ibm.com> Signed-off-by:
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Kajol Jain authored
Patch here adds cpu hotplug functions to hv_24x7 pmu. A new cpuhp_state "CPUHP_AP_PERF_POWERPC_HV_24x7_ONLINE" enum is added. The online callback function updates the cpumask only if its empty. As the primary intention of adding hotplug support is to designate a CPU to make HCALL to collect the counter data. The offline function test and clear corresponding cpu in a cpumask and update cpumask to any other active cpu. Signed-off-by:
Gautham R. Shenoy <ego@linux.vnet.ibm.com> Signed-off-by:
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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:
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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:
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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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