- 21 Apr, 2021 13 commits
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Christophe Leroy authored
Its name comes from former probe_user_read() function. That function is now called copy_from_user_nofault(). probe_user_read_inst() uses copy_from_user_nofault() to read only a few bytes. It is suboptimal. It does the same as get_user_inst() but in addition disables page faults. But on the other hand, it is not used for the time being. So remove it for now. If one day it is really needed, we can give it a new name more in line with today's naming, and implement it using get_user_inst() Signed-off-by:
Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by:
Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/5f6f82572242a59bfee1e19a71194d8f7ef5fca4.1618405715.git.christophe.leroy@csgroup.eu
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Christophe Leroy authored
If the target of a function call is within 32 Mbytes distance, use a standard function call with 'bl' instead of the 'lis/ori/mtlr/blrl' sequence. In the first pass, no memory has been allocated yet and the code position is not known yet (image pointer is NULL). This pass is there to calculate the amount of memory to allocate for the EBPF code, so assume the 4 instructions sequence is required, so that enough memory is allocated. Signed-off-by:
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Christophe Leroy authored
Re-implement BPF_ALU64 | BPF_{LSH/RSH/ARSH} | BPF_X with branchless implementation copied from misc_32.S. Signed-off-by: -
Christophe Leroy authored
Replace <<== by <<= Signed-off-by:
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Christophe Leroy authored
wrtspr() is a function to write an arbitrary value in a special register. It is used on 8xx to write to SPRN_NRI, SPRN_EID and SPRN_EIE. Writing any value to one of those will play with MSR EE and MSR RI regardless of that value. r0 is used many places in the generated code and using r0 for that creates an unnecessary dependency of this instruction with preceding ones using r0 in a few places in vmlinux. r2 is most likely the most stable register as it contains the pointer to 'current'. Using r2 instead of r0 avoids that unnecessary dependency. Signed-off-by:
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Christophe Leroy authored
On powerpc: - VDSO library is named linux-vdso32.so.1 or linux-vdso64.so.1 - clock_gettime is named __kernel_clock_gettime() Ensure gettime_perf tries these names before giving up. Signed-off-by:
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Ganesh Goudar authored
When we hit an UE while using machine check safe copy routines, ignore_event flag is set and the event is ignored by mce handler, And the flag is also saved for defered handling and printing of mce event information, But as of now saving of this flag is done on checking if the effective address is provided or physical address is calculated, which is not right. Save ignore_event flag regardless of whether the effective address is provided or physical address is calculated. Without this change following log is seen, when the event is to be ignored. [ 512.971365] MCE: CPU1: machine check (Severe) UE Load/Store [Recovered] [ 512.971509] MCE: CPU1: NIP: [c0000000000b67c0] memcpy+0x40/0x90 [ 512.971655] MCE: CPU1: Initiator CPU [ 512.971739] MCE: CPU1: Unknown [ 512.972209] MCE: CPU1: machine check (Severe) UE Load/Store [Recovered] [ 512.972334] MCE: CPU1: NIP: [c0000000000b6808] memcpy+0x88/0x90 [ 512.972456] MCE: CPU1: Initiator CPU [ 512.972534] MCE: CPU1: Unknown Signed-off-by:
Ganesh Goudar <ganeshgr@linux.ibm.com> Reviewed-by:
Santosh Sivaraj <santosh@fossix.org> Signed-off-by:
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Christophe Leroy authored
For that, create a 32 bits version of patch_imm64_load_insns() and create a patch_imm_load_insns() which calls patch_imm32_load_insns() on PPC32 and patch_imm64_load_insns() on PPC64. Adapt optprobes_head.S for PPC32. Use PPC_LL/PPC_STL macros instead of raw ld/std, opt out things linked to paca and use stmw/lmw to save/restore registers. Signed-off-by:
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Christophe Leroy authored
In order to simplify use on PPC32, change ppc_inst_as_u64() into ppc_inst_as_ulong() that returns the 32 bits instruction on PPC32. Will be used when porting OPTPROBES to PPC32. Signed-off-by:
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Christophe Leroy authored
This patch makes use of trap types in irq.c Signed-off-by:
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Christophe Leroy authored
This patch makes use of trap types in head_book3s_32.S Signed-off-by:
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Christophe Leroy authored
This patch makes use of trap types in head_8xx.S Signed-off-by:
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Leonardo Bras authored
As of today, if the DDW is big enough to fit (1 << MAX_PHYSMEM_BITS) it's possible to use direct DMA mapping even with pmem region. But, if that happens, the window size (len) is set to (MAX_PHYSMEM_BITS - page_shift) instead of MAX_PHYSMEM_BITS, causing a pagesize times smaller DDW to be created, being insufficient for correct usage. Fix this so the correct window size is used in this case. Fixes: bf6e2d56 ("powerpc/dma: Fallback to dma_ops when persistent memory present") Signed-off-by:
Leonardo Bras <leobras.c@gmail.com> Reviewed-by:
Alexey Kardashevskiy <aik@ozlabs.ru> Signed-off-by:
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- 20 Apr, 2021 9 commits
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Michael Ellerman authored
The changes to add KUAP support with the hash MMU broke booting of KVM PR guests. The symptom is no visible progress of the guest, or possibly just "SLOF" being printed to the qemu console. Host code is still executing, but breaking into xmon might show a stack trace such as: __might_fault+0x84/0xe0 (unreliable) kvm_read_guest+0x1c8/0x2f0 [kvm] kvmppc_ld+0x1b8/0x2d0 [kvm] kvmppc_load_last_inst+0x50/0xa0 [kvm] kvmppc_exit_pr_progint+0x178/0x220 [kvm_pr] kvmppc_handle_exit_pr+0x31c/0xe30 [kvm_pr] after_sprg3_load+0x80/0x90 [kvm_pr] kvmppc_vcpu_run_pr+0x104/0x260 [kvm_pr] kvmppc_vcpu_run+0x34/0x48 [kvm] kvm_arch_vcpu_ioctl_run+0x340/0x450 [kvm] kvm_vcpu_ioctl+0x2ac/0x8c0 [kvm] sys_ioctl+0x320/0x1060 system_call_exception+0x160/0x270 system_call_common+0xf0/0x27c Bisect points to commit b2ff33a1 ("powerpc/book3s64/hash/kuap: Enable kuap on hash"), but that's just the commit that enabled KUAP with hash and made the bug visible. The root cause seems to be that KVM PR is creating kernel mappings that don't use the correct key, since we switched to using key 3. We have a helper for adding the right key value, however it's designed to take a pteflags variable, which the KVM code doesn't have. But we can make it work by passing 0 for the pteflags, and tell it explicitly that it should use the kernel key. With that changed guests boot successfully. Fixes: d94b827e ("powerpc/book3s64/kuap: Use Key 3 for kernel mapping with hash translation") Cc: stable@vger.kernel.org # v5.11+ Signed-off-by:
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Michael Ellerman authored
RCU complains about us calling printk() from an offline CPU: ============================= WARNING: suspicious RCU usage 5.12.0-rc7-02874-g7cf90e481cb8 #1 Not tainted ----------------------------- kernel/locking/lockdep.c:3568 RCU-list traversed in non-reader section!! other info that might help us debug this: RCU used illegally from offline CPU! rcu_scheduler_active = 2, debug_locks = 1 no locks held by swapper/0/0. stack backtrace: CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.12.0-rc7-02874-g7cf90e481cb8 #1 Call Trace: dump_stack+0xec/0x144 (unreliable) lockdep_rcu_suspicious+0x124/0x144 __lock_acquire+0x1098/0x28b0 lock_acquire+0x128/0x600 _raw_spin_lock_irqsave+0x6c/0xc0 down_trylock+0x2c/0x70 __down_trylock_console_sem+0x60/0x140 vprintk_emit+0x1a8/0x4b0 vprintk_func+0xcc/0x200 printk+0x40/0x54 pseries_cpu_offline_self+0xc0/0x120 arch_cpu_idle_dead+0x54/0x70 do_idle+0x174/0x4a0 cpu_startup_entry+0x38/0x40 rest_init+0x268/0x388 start_kernel+0x748/0x790 start_here_common+0x1c/0x614 Which happens because by the time we get to rtas_stop_self() we are already offline. In addition the message can be spammy, and is not that helpful for users, so remove it. Signed-off-by: -
Michael Ellerman authored
We have some interesting code in our Makefile to define _TASK_CPU, based on awk'ing the value out of asm-offsets.h. It exists to circumvent some circular header dependencies that prevent us from referring to task_struct in the relevant code. See the comment around _TASK_CPU in smp.h for more detail. Maybe one day we can come up with a better solution, but for now we can at least limit that logic to 32-bit, because it's not needed for 64-bit. Signed-off-by:
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Tyrel Datwyler authored
Currently, neither the vio_bus or vio_driver structures provide support for a shutdown() routine. Add support for shutdown() by allowing drivers to provide a implementation via function pointer in their vio_driver struct and provide a proper implementation in the driver template for the vio_bus that calls a vio drivers shutdown() if defined. In the case that no shutdown() is defined by a vio driver and a kexec is in progress we implement a big hammer that calls remove() to ensure no further DMA for the devices is possible. Signed-off-by:
Tyrel Datwyler <tyreld@linux.ibm.com> Signed-off-by:
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Athira Rajeev authored
Performance Monitoring Unit (PMU) registers in powerpc provides information on cycles elapsed between different stages in the pipeline. This can be used for application tuning. On ISA v3.1 platform, this information is exposed by sampling registers. Patch adds kernel support to capture two of the cycle counters as part of perf sample using the sample type: PERF_SAMPLE_WEIGHT_STRUCT. The power PMU function 'get_mem_weight' currently uses 64 bit weight field of perf_sample_data to capture memory latency. But following the introduction of PERF_SAMPLE_WEIGHT_TYPE, weight field could contain 64-bit or 32-bit value depending on the architexture support for PERF_SAMPLE_WEIGHT_STRUCT. Patches uses WEIGHT_STRUCT to expose the pipeline stage cycles info. Hence update the ppmu functions to work for 64-bit and 32-bit weight values. If the sample type is PERF_SAMPLE_WEIGHT, use the 64-bit weight field. if the sample type is PERF_SAMPLE_WEIGHT_STRUCT, memory subsystem latency is stored in the low 32bits of perf_sample_weight structure. Also for CPU_FTR_ARCH_31, capture the two cycle counter information in two 16 bit fields of perf_sample_weight structure. Signed-off-by:
Athira Rajeev <atrajeev@linux.vnet.ibm.com> Reviewed-by:
Madhavan Srinivasan <maddy@linux.ibm.com> Signed-off-by:
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Haren Myneni authored
The links that are mentioned in this document are no longer valid. So changed the proper links for NXGZIP user manual and test cases. Reported-by:
Bulent Abali <abali@us.ibm.com> Signed-off-by:
Haren Myneni <haren@linux.ibm.com> Signed-off-by:
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Daniel Henrique Barboza authored
The RTAS set-indicator call, when attempting to UNISOLATE a DRC that is already UNISOLATED or CONFIGURED, returns RTAS_OK and does nothing else for both QEMU and phyp. This gives us an opportunity to use this behavior to signal the hypervisor layer when an error during device removal happens, allowing it to do a proper error handling, while not breaking QEMU/phyp implementations that don't have this support. This patch introduces this idea by unisolating all CPU DRCs that failed to be removed by dlpar_cpu_remove_by_index(), when handling the PSERIES_HP_ELOG_ID_DRC_INDEX event. This is being done for this event only because its the only CPU removal event QEMU uses, and there's no need at this moment to add this mechanism for phyp only code. Signed-off-by:
Daniel Henrique Barboza <danielhb413@gmail.com> Reviewed-by:
David Gibson <david@gibson.dropbear.id.au> Signed-off-by:
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Daniel Henrique Barboza authored
Next patch will execute a set-indicator call in hotplug-cpu.c. Create a dlpar_unisolate_drc() helper to avoid spreading more rtas_set_indicator() calls outside of dlpar.c. Signed-off-by:
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Ganesh Goudar authored
The error type is ICACHE not DCACHE, for case MCE_ERROR_TYPE_ICACHE. Signed-off-by:
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- 19 Apr, 2021 2 commits
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Michael Ellerman authored
sfr reports that the allyesconfig build fails with: arch/powerpc/kernel/fadump.c: In function 'crash_fadump': arch/powerpc/kernel/fadump.c:731:28: error: 'INTERRUPT_SYSTEM_RESET' undeclared 731 | if (TRAP(&(fdh->regs)) == INTERRUPT_SYSTEM_RESET) { Add an include of interrupt.h to fix it. Fixes: 7153d4bf ("powerpc/traps: Enhance readability for trap types") Signed-off-by:Stephen Rothwell <sfr@canb.auug.org.au> [mpe: Reformat change log] Signed-off-by:
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Madhavan Srinivasan authored
Add platform specific attr.config value checks. Patch includes checks for both power9 and power10. Signed-off-by:
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- 18 Apr, 2021 2 commits
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Michael Ellerman authored
Merge some powerpc KVM patches we are keeping in a topic branch just in case anyone else needs to merge them.
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Nicholas Piggin authored
Starting with ISA v3.1, LPCR[AIL] no longer controls the interrupt mode for HV=1 interrupts. Instead, a new LPCR[HAIL] bit is defined which behaves like AIL=3 for HV interrupts when set. Set HAIL on bare metal to give us mmu-on interrupts and improve performance. This also fixes an scv bug: we don't implement scv real mode (AIL=0) vectors because they are at an inconvenient location, so we just disable scv support when AIL can not be set. However powernv assumes that LPCR[AIL] will enable AIL mode so it enables scv support despite HV interrupts being AIL=0, which causes scv interrupts to go off into the weeds. Fixes: 7fa95f9a ("powerpc/64s: system call support for scv/rfscv instructions") Cc: stable@vger.kernel.org # v5.9+ Signed-off-by:
Nicholas Piggin <npiggin@gmail.com> Signed-off-by:
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- 17 Apr, 2021 7 commits
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Srikar Dronamraju authored
Geethika reported a trace when doing a dlpar CPU add. ------------[ cut here ]------------ WARNING: CPU: 152 PID: 1134 at kernel/sched/topology.c:2057 CPU: 152 PID: 1134 Comm: kworker/152:1 Not tainted 5.12.0-rc5-master #5 Workqueue: events cpuset_hotplug_workfn NIP: c0000000001cfc14 LR: c0000000001cfc10 CTR: c0000000007e3420 REGS: c0000034a08eb260 TRAP: 0700 Not tainted (5.12.0-rc5-master+) MSR: 8000000000029033 <SF,EE,ME,IR,DR,RI,LE> CR: 28828422 XER: 00000020 CFAR: c0000000001fd888 IRQMASK: 0 #012GPR00: c0000000001cfc10 c0000034a08eb500 c000000001f35400 0000000000000027 #012GPR04: c0000035abaa8010 c0000035abb30a00 0000000000000027 c0000035abaa8018 #012GPR08: 0000000000000023 c0000035abaaef48 00000035aa540000 c0000035a49dffe8 #012GPR12: 0000000028828424 c0000035bf1a1c80 0000000000000497 0000000000000004 #012GPR16: c00000000347a258 0000000000000140 c00000000203d468 c000000001a1a490 #012GPR20: c000000001f9c160 c0000034adf70920 c0000034aec9fd20 0000000100087bd3 #012GPR24: 0000000100087bd3 c0000035b3de09f8 0000000000000030 c0000035b3de09f8 #012GPR28: 0000000000000028 c00000000347a280 c0000034aefe0b00 c0000000010a2a68 NIP [c0000000001cfc14] build_sched_domains+0x6a4/0x1500 LR [c0000000001cfc10] build_sched_domains+0x6a0/0x1500 Call Trace: [c0000034a08eb500] [c0000000001cfc10] build_sched_domains+0x6a0/0x1500 (unreliable) [c0000034a08eb640] [c0000000001d1e6c] partition_sched_domains_locked+0x3ec/0x530 [c0000034a08eb6e0] [c0000000002936d4] rebuild_sched_domains_locked+0x524/0xbf0 [c0000034a08eb7e0] [c000000000296bb0] rebuild_sched_domains+0x40/0x70 [c0000034a08eb810] [c000000000296e74] cpuset_hotplug_workfn+0x294/0xe20 [c0000034a08ebc30] [c000000000178dd0] process_one_work+0x300/0x670 [c0000034a08ebd10] [c0000000001791b8] worker_thread+0x78/0x520 [c0000034a08ebda0] [c000000000185090] kthread+0x1a0/0x1b0 [c0000034a08ebe10] [c00000000000ccec] ret_from_kernel_thread+0x5c/0x70 Instruction dump: 7d2903a6 4e800421 e8410018 7f67db78 7fe6fb78 7f45d378 7f84e378 7c681b78 3c62ff1a 3863c6f8 4802dc35 60000000 <0fe00000> 3920fff4 f9210070 e86100a0 ---[ end trace 532d9066d3d4d7ec ]--- Some of the per-CPU masks use cpu_cpu_mask as a filter to limit the search for related CPUs. On a dlpar add of a CPU, update cpu_cpu_mask before updating the per-CPU masks. This will ensure the cpu_cpu_mask is updated correctly before its used in setting the masks. Setting the numa_node will ensure that when cpu_cpu_mask() gets called, the correct node number is used. This code movement helped fix the above call trace. Reported-by:
Geetika Moolchandani <Geetika.Moolchandani1@ibm.com> Signed-off-by:
Srikar Dronamraju <srikar@linux.vnet.ibm.com> Reviewed-by:
Nathan Lynch <nathanl@linux.ibm.com> Signed-off-by:
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Xiongwei Song authored
Define macros to list ppc interrupt types in interttupt.h, replace the reference of the trap hex values with these macros. Referred the hex numbers in arch/powerpc/kernel/exceptions-64e.S, arch/powerpc/kernel/exceptions-64s.S, arch/powerpc/kernel/head_*.S, arch/powerpc/kernel/head_booke.h and arch/powerpc/include/asm/kvm_asm.h. Signed-off-by:
Xiongwei Song <sxwjean@gmail.com> [mpe: Resolve conflicts in nmi_disables_ftrace(), fix 40x build] Signed-off-by:
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Tony Ambardar authored
A few archs like powerpc have different errno.h values for macros EDEADLOCK and EDEADLK. In code including both libc and linux versions of errno.h, this can result in multiple definitions of EDEADLOCK in the include chain. Definitions to the same value (e.g. seen with mips) do not raise warnings, but on powerpc there are redefinitions changing the value, which raise warnings and errors (if using "-Werror"). Guard against these redefinitions to avoid build errors like the following, first seen cross-compiling libbpf v5.8.9 for powerpc using GCC 8.4.0 with musl 1.1.24: In file included from ../../arch/powerpc/include/uapi/asm/errno.h:5, from ../../include/linux/err.h:8, from libbpf.c:29: ../../include/uapi/asm-generic/errno.h:40: error: "EDEADLOCK" redefined [-Werror] #define EDEADLOCK EDEADLK In file included from toolchain-powerpc_8540_gcc-8.4.0_musl/include/errno.h:10, from libbpf.c:26: toolchain-powerpc_8540_gcc-8.4.0_musl/include/bits/errno.h:58: note: this is the location of the previous definition #define EDEADLOCK 58 cc1: all warnings being treated as errors Cc: Stable <stable@vger.kernel.org> Reported-by:Rosen Penev <rosenp@gmail.com> Signed-off-by:
Tony Ambardar <Tony.Ambardar@gmail.com> Signed-off-by:
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Srikar Dronamraju authored
On systems with large CPUs per node, even with the filtered matching of related CPUs, there can be large number of calls to cpu_to_chip_id for the same CPU. For example with 4096 vCPU, 1 node QEMU configuration, with 4 threads per core, system could be see upto 1024 calls to cpu_to_chip_id() for the same CPU. On a given system, cpu_to_chip_id() for a given CPU would always return the same. Hence cache the result in a lookup table for use in subsequent calls. Since all CPUs sharing the same core will belong to the same chip, the lookup_table has an entry for one CPU per core. chip_id_lookup_table is not being freed and would be used on subsequent CPU online post CPU offline. Reported-by:
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Srikar Dronamraju authored
Now that cpu_core_mask has been reintroduced, lets revert commit 4bce5459 ("powerpc/topology: Update topology_core_cpumask") Post this commit, lscpu should reflect topologies as requested by a user when a QEMU instance is launched with NUMA spanning multiple sockets. Reported-by:
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Srikar Dronamraju authored
Daniel reported that with Commit 4ca234a9 ("powerpc/smp: Stop updating cpu_core_mask") QEMU was unable to set single NUMA node SMP topologies such as: -smp 8,maxcpus=8,cores=2,threads=2,sockets=2 i.e he expected 2 sockets in one NUMA node. The above commit helped to reduce boot time on Large Systems for example 4096 vCPU single socket QEMU instance. PAPR is silent on having more than one socket within a NUMA node. cpu_core_mask and cpu_cpu_mask for any CPU would be same unless the number of sockets is different from the number of NUMA nodes. One option is to reintroduce cpu_core_mask but use a slightly different method to arrive at the cpu_core_mask. Previously each CPU's chip-id would be compared with all other CPU's chip-id to verify if both the CPUs were related at the chip level. Now if a CPU 'A' is found related / (unrelated) to another CPU 'B', all the thread siblings of 'A' and thread siblings of 'B' are automatically marked as related / (unrelated). Also if a platform doesn't support ibm,chip-id property, i.e its cpu_to_chip_id returns -1, cpu_core_map holds a copy of cpu_cpu_mask(). Fixes: 4ca234a9 ("powerpc/smp: Stop updating cpu_core_mask") Reported-by:
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Cédric Le Goater authored
The 'chip_id' field of the XIVE CPU structure is used to choose a target for a source located on the same chip. For that, the XIVE driver queries the chip identifier from the "ibm,chip-id" property and compares it to a 'src_chip' field identifying the chip of a source. This information is only available on the PowerNV platform, 'src_chip' being assigned to XIVE_INVALID_CHIP_ID under pSeries. The "ibm,chip-id" property is also not available on all platforms. It was first introduced on PowerNV and later, under QEMU for pSeries/KVM. However, the property is not part of PAPR and does not exist under pSeries/PowerVM. Assign 'chip_id' to XIVE_INVALID_CHIP_ID by default and let the PowerNV platform override the value with the "ibm,chip-id" property. Signed-off-by:
Cédric Le Goater <clg@kaod.org> Signed-off-by:
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- 16 Apr, 2021 4 commits
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Tyrel Datwyler authored
The pci_bus->bridge reference may no longer be valid after pci_bus_remove() resulting in passing a bad value to device_unregister() for the associated bridge device. Store the host_bridge reference in a separate variable prior to pci_bus_remove(). Fixes: 73400565 ("powerpc/pci: Reorder pci bus/bridge unregistration during PHB removal") Signed-off-by:
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Michael Ellerman authored
Now that __fake_sleep is static, we get a warning about it being unused in some configurations: drivers/macintosh/via-pmu.c:190:12: warning: '__fake_sleep' defined but not used 190 | static int __fake_sleep; Move it inside the ifdef where it's used to avoid the warning. Fixes: 95d14392 ("macintosh/via-pmu: Make some symbols static") Reported-by: -
Michael Ellerman authored
When I changed the rc variable to be long rather than int64_t I neglected to update the printk(), leading to a build break: arch/powerpc/platforms/pseries/papr_scm.c: In function 'papr_scm_pmem_flush': arch/powerpc/platforms/pseries/papr_scm.c:144:26: warning: format '%lld' expects argument of type 'long long int', but argument 3 has type 'long int' [-Wformat=] Fixes: 75b7c05e ("powerpc/papr_scm: Implement support for H_SCM_FLUSH hcall") Reported-by: -
Michael Ellerman authored
This is a pseries only driver, it should be built by default as part of pseries_defconfig to get some build coverage. Signed-off-by:
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- 14 Apr, 2021 3 commits
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Michael Ellerman authored
The lkp bot pointed out that with W=1 we get: arch/powerpc/mm/book3s64/radix_pgtable.c:183:6: error: no previous prototype for 'radix__change_memory_range' Which is really saying that it could be static, make it so. Reported-by:
kernel test robot <lkp@intel.com> Signed-off-by:
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Christophe Leroy authored
This patch adds the necessary glue to provide time namespaces. Things are mainly copied from ARM64. __arch_get_timens_vdso_data() calculates timens vdso data position based on the vdso data position, knowing it is the next page in vvar. This avoids having to redo the mflr/bcl/mflr/mtlr dance to locate the page relative to running code position. Signed-off-by:
Andrei Vagin <avagin@gmail.com> Signed-off-by:
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Dmitry Safonov authored
Since commit 511157ab ("powerpc/vdso: Move vdso datapage up front") VVAR page is in front of the VDSO area. In result it breaks CRIU (Checkpoint Restore In Userspace) [1], where CRIU expects that "[vdso]" from /proc/../maps points at ELF/vdso image, rather than at VVAR data page. Laurent made a patch to keep CRIU working (by reading aux vector). But I think it still makes sence to separate two mappings into different VMAs. It will also make ppc64 less "special" for userspace and as a side-bonus will make VVAR page un-writable by debugger (which previously would COW page and can be unexpected). I opportunistically Cc stable on it: I understand that usually such stuff isn't a stable material, but that will allow us in CRIU have one workaround less that is needed just for one release (v5.11) on one platform (ppc64), which we otherwise have to maintain. I wouldn't go as far as to say that the commit 511157ab is ABI regression as no other userspace got broken, but I'd really appreciate if it gets backported to v5.11 after v5.12 is released, so as not to complicate already non-simple CRIU-vdso code. Thanks! [1]: https://github.com/checkpoint-restore/criu/issues/1417 Cc: stable@vger.kernel.org # v5.11 Signed-off-by:
Dmitry Safonov <dima@arista.com> Signed-off-by:
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