- 27 Feb, 2024 2 commits
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Ingo Molnar authored
This was already defined locally by init/main.c, but let's make it generic, as arch/x86/kernel/cpu/topology.c is going to make use of it to have more uniform code. Reviewed-by:
Thomas Gleixner <tglx@linutronix.de> Cc: linux-kernel@vger.kernel.org Signed-off-by:
Ingo Molnar <mingo@kernel.org>
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Ingo Molnar authored
bringup_nonboot_cpus() gets passed the 'setup_max_cpus' variable in init/main.c - which is also the name of the parameter, shadowing the name. To reduce confusion and to allow the 'setup_max_cpus' value to be #defined in the <linux/smp.h> header, use the 'max_cpus' name for the function parameter name. Signed-off-by:
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- 16 Feb, 2024 1 commit
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Thomas Gleixner authored
Now that __num_cores_per_package and __num_threads_per_package are available, cpuinfo::x86_max_cores and the related math all over the place can be replaced with the ready to consume data. Signed-off-by:
Michael Kelley <mhklinux@outlook.com> Tested-by:
Sohil Mehta <sohil.mehta@intel.com> Link: https://lore.kernel.org/r/20240213210253.176147806@linutronix.de
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- 15 Feb, 2024 37 commits
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Thomas Gleixner authored
Expose properly accounted information and accessors so the fiddling with other topology variables can be replaced. Signed-off-by:
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Thomas Gleixner authored
The plural of die is dies. Signed-off-by:
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Thomas Gleixner authored
It's really a non-intuitive name. Rename it to __max_threads_per_core which is obvious. Signed-off-by:
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Thomas Gleixner authored
Similar to other sizing information the number of cores per package can be established from the topology bitmap. Provide a function for retrieving that information and replace the buggy hack in the CPUID evaluation with it. Signed-off-by:
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Thomas Gleixner authored
Replace the logical package and die management functionality and retrieve the logical IDs from the topology bitmaps. Signed-off-by:
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Thomas Gleixner authored
With the topology bitmaps in place the logical package and die IDs can trivially be retrieved by determining the bitmap weight of the relevant topology domain level up to and including the physical ID in question. Provide a function to that effect. Signed-off-by:
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Thomas Gleixner authored
No point in creating a mask via fls(). smp_num_siblings is guaranteed to be a power of 2. So just using (smp_num_siblings - 1) has the same effect. Signed-off-by:
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Thomas Gleixner authored
The early initcall to initialize the primary thread mask is not longer required because topology_init_possible_cpus() can mark primary threads correctly when initializing the possible and present map as the number of SMT threads is already determined correctly. The XENPV workaround is not longer required because XENPV now registers fake APIC IDs which will just work like any other enumeration. Signed-off-by:
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Thomas Gleixner authored
Now that all possible APIC IDs are tracked in the topology bitmaps, its trivial to retrieve the real information from there. This gets rid of the guesstimates for the maximal packages and dies per package as the actual numbers can be determined before a single AP has been brought up. The number of SMT threads can now be determined correctly from the bitmaps in all situations. Up to now a system which has SMT disabled in the BIOS will still claim that it is SMT capable, because the lowest APIC ID bit is reserved for that and CPUID leaf 0xb/0x1f still enumerates the SMT domain accordingly. By calculating the bitmap weights of the SMT and the CORE domain and setting them into relation the SMT disabled in BIOS situation reports correctly that the system is not SMT capable. It also handles the situation correctly when a hybrid systems boot CPU does not have SMT as it takes the SMT capability of the APs fully into account. Signed-off-by:
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Thomas Gleixner authored
It turns out that XEN/PV Dom0 has halfways usable CPUID/MADT enumeration except that it cannot deal with CPUs which are enumerated as disabled in MADT. DomU has no MADT and provides at least rudimentary topology information in CPUID leaves 1 and 4. For both it's important that there are not more possible Linux CPUs than vCPUs provided by the hypervisor. As this is ensured by counting the vCPUs before enumeration happens: - lift the restrictions in the CPUID evaluation and the MADT parser - Utilize MADT registration for Dom0 - Keep the fake APIC ID registration for DomU - Fix the XEN APIC fake so the readout of the local APIC ID works for Dom0 via the hypercall and for DomU by returning the registered fake APIC IDs. With that the XEN/PV fake approximates usefulness. Signed-off-by: -
Thomas Gleixner authored
XEN/PV has a completely broken vCPU enumeration scheme, which just works by chance and provides zero topology information. Each vCPU ends up being a single core package. Dom0 provides MADT which can be used for topology information, but that table is the unmodified host table, which means that there can be more CPUs registered than the number of vCPUs XEN provides for the dom0 guest. DomU does not have ACPI and both rely on counting the possible vCPUs via an hypercall. To prepare for using CPUID topology information either via MADT or via fake APIC IDs count the number of possible CPUs during early boot and adjust nr_cpu_ids() accordingly. Signed-off-by:
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Thomas Gleixner authored
There is no point in assigning the CPU numbers during ACPI physical hotplug. The number of possible hotplug CPUs is known when the possible map is initialized, so the CPU numbers can be associated to the registered non-present APIC IDs right there. This allows to put more code into the __init section and makes the related data __ro_after_init. Signed-off-by:
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Thomas Gleixner authored
The topology bitmaps track all possible APIC IDs which have been registered during enumeration. As sizing and further topology information is going to be derived from these bitmaps, reject attempts to hotplug an APIC ID which was not registered during enumeration. Signed-off-by:
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Thomas Gleixner authored
Topology on X86 is determined by the registered APIC IDs and the segmentation information retrieved from CPUID. Depending on the granularity of the provided CPUID information the most fine grained scheme looks like this according to Intel terminology: [PKG][DIEGRP][DIE][TILE][MODULE][CORE][THREAD] Not enumerated domain levels consume 0 bits in the APIC ID. This allows to provide a consistent view at the topology and determine other information precisely like the number of cores in a package on hybrid systems, where the existing assumption that number or cores == number of threads / threads per core does not hold. Provide per domain level bitmaps which record the APIC ID split into the domain levels to make later evaluation of domain level specific information simple. This allows to calculate e.g. the logical IDs without any further extra logic. Contrary to the existing registration mechanism this records disabled CPUs, which are subject to later hotplug as well. That's useful for boot time sizing of package or die dependent allocations without using heuristics. Signed-off-by:
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Thomas Gleixner authored
When a kdump kernel is started from a crashing CPU then there is no guarantee that this CPU is the real boot CPU (BSP). If the kdump kernel tries to online the BSP then the INIT sequence will reset the machine. There is a command line option to prevent this, but in case of nested kdump kernels this is wrong. But that command line option is not required at all because the real BSP is enumerated as the first CPU by firmware. Support for the only known system which was different (Voyager) got removed long ago. Detect whether the boot CPU APIC ID is the first APIC ID enumerated by the firmware. If the first APIC ID enumerated is not matching the boot CPU APIC ID then skip registering it. Signed-off-by:
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Thomas Gleixner authored
Managing possible CPUs is an unreadable and uncomprehensible maze. Aside of that it's backwards because it applies command line limits after registering all APICs. Rewrite it so that it: - Applies the command line limits upfront so that only the allowed amount of APIC IDs can be registered. - Applies eventual late restrictions in an understandable way - Uses simple min_t() calculations which are trivial to follow. - Provides a separate function for resetting to UP mode late in the bringup process. Signed-off-by: -
Thomas Gleixner authored
Move the actually required content of generic_processor_id() into the call sites and use common helper functions for them. This separates the early boot registration and the ACPI hotplug mechanism completely which allows further cleanups and improvements. Signed-off-by:
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Thomas Gleixner authored
"smpboot: native_kick_ap: bad cpu 33" is absolutely useless information. Replace it with something meaningful which allows to decode the failure condition. Signed-off-by:
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Thomas Gleixner authored
Put the processor accounting into a data structure, which will gain more topology related information in the next steps, and sanitize the accounting. Signed-off-by:
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Thomas Gleixner authored
Having the same check whether the number of assigned CPUs has reached the nr_cpu_ids limit twice in the same code path is pointless. Repeating the information that CPUs are ignored over and over is also pointless noise. Remove the redundant check and reduce the noise by using a pr_warn_once(). Signed-off-by:
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Thomas Gleixner authored
Now that all external fiddling with num_processors and disabled_cpus is gone, move the last user prefill_possible_map() into the topology code too and remove the global visibility of these variables. Signed-off-by:
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Thomas Gleixner authored
XENPV does not use the APIC. It's just piggy packing on the infrastructure and fiddles with global variables as it sees fit. These global variables are going away, so let XENPV register pseudo APIC IDs to keep the accounting correct and keep up the illusion that XEN/PV is something sane. Signed-off-by:
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Thomas Gleixner authored
The MADT table for XEN/PV dom0 is not really useful and registering the APICs is momentarily a pointless exercise because XENPV does not use an APIC at all. It overrides the x86_init.mpparse.parse_smp_config() callback, resets num_processors and counts how many of them are provided by the hypervisor. This is in the way of cleaning up the APIC registration. Prevent MADT registration for XEN/PV temporarily until the rework is completed and XEN/PV can use the MADT again. Signed-off-by:
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Thomas Gleixner authored
Aside of switching over to the new interface, record the number of registered CPUs locally, which allows to make num_processors and disabled_cpus confined to the topology code. No functional change intended. Signed-off-by:
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Thomas Gleixner authored
No functional change intended. Signed-off-by:
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Thomas Gleixner authored
No functional change intended. Signed-off-by:
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Thomas Gleixner authored
Use the new topology registration functions and make the early boot code path __init. No functional change intended. Signed-off-by:
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Thomas Gleixner authored
generic_processor_info() aside of being a complete misnomer is used for both early boot registration and ACPI CPU hotplug. While it's arguable that this can share some code, it results in code which is hard to understand and kept around post init for no real reason. Also the call sites do lots of manual fiddling in topology related variables instead of having proper interfaces for the purpose which handle the topology internals correctly. Provide topology_register_apic(), topology_hotplug_apic() and topology_hotunplug_apic() which have the extra magic of the call sites incorporated and for now are wrappers around generic_processor_info(). Signed-off-by:
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Thomas Gleixner authored
The APIC/CPU registration sits in the middle of the APIC code. In fact this is a topology evaluation function and has nothing to do with the inner workings of the local APIC. Move it out into a file which reflects what this is about. Signed-off-by:
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Thomas Gleixner authored
The ACPI ID for CPUs is preset with U32_MAX which is completely non obvious. Use a proper define for it. Signed-off-by:
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Thomas Gleixner authored
Paranoia is not wrong, but having an APIC callback which is in most implementations a complete NOOP and in one actually looking whether the APICID of an upcoming CPU has been registered. The same APICID which was used to bring the CPU out of wait for startup. That's paranoia for the paranoia sake. Remove the voodoo. Signed-off-by:
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Thomas Gleixner authored
There is absolutely no point to write the APIC ID which was read from the local APIC earlier, back into the local APIC for the 64-bit UP case. Remove that along with the apic callback which is solely there for this pointless exercise. Signed-off-by:
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Thomas Gleixner authored
physid_t is a wrapper around bitmap. Just remove the onion layer and use bitmap functionality directly. Signed-off-by:
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Thomas Gleixner authored
There is no reason to have the early mptable evaluation conditionally invoked only from the AMD numa topology code. Make it explicit and invoke it from setup_arch() right after the corresponding ACPI init call. Remove the pointless wrapper and invoke x86_init::mpparse::early_parse_smp_config() directly. Signed-off-by:
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Thomas Gleixner authored
Now that all platforms have the new split SMP configuration callbacks set up, flip the switch and remove the old callback pointer and mop up the platform code. Signed-off-by:
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Thomas Gleixner authored
Initialize the new callbacks in preparation for switching the core code. Signed-off-by:
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Thomas Gleixner authored
Provide a wrapper around the existing function and fill the new callbacks in. No functional change as the new callbacks are not yet operational. Signed-off-by:
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