user/sven/linux.git/drivers/base/cpu.c, branch v6.7.9

drivers/base/cpu: crash data showing should depends on KEXEC_CORE

2023-12-07T00:12:48Z

After commit 88a6f8994421 ("crash: memory and CPU hotplug sysfs attributes"), on x86_64, if only below kernel configs related to kdump are set, compiling error are triggered. ---- CONFIG_CRASH_CORE=y CONFIG_KEXEC_CORE=y CONFIG_CRASH_DUMP=y CONFIG_CRASH_HOTPLUG=y ------ ------------------------------------------------------ drivers/base/cpu.c: In function `crash_hotplug_show': drivers/base/cpu.c:309:40: error: implicit declaration of function `crash_hotplug_cpu_support'; did you mean `crash_hotplug_show'? [-Werror=implicit-function-declaration] 309 | return sysfs_emit(buf, "%d\n", crash_hotplug_cpu_support()); | ^~~~~~~~~~~~~~~~~~~~~~~~~ | crash_hotplug_show cc1: some warnings being treated as errors ------------------------------------------------------ CONFIG_KEXEC is used to enable kexec_load interface, the crash_notes/crash_notes_size/crash_hotplug showing depends on CONFIG_KEXEC is incorrect. It should depend on KEXEC_CORE instead. Fix it now. Link: https://lkml.kernel.org/r/20231128055248.659808-1-bhe@redhat.com Fixes: 88a6f8994421 ("crash: memory and CPU hotplug sysfs attributes") Signed-off-by: Baoquan He Tested-by: Ignat Korchagin [compile-time only] Tested-by: Alexander Gordeev Reviewed-by: Eric DeVolder Cc: Signed-off-by: Andrew Morton

Merge tag 'driver-core-6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

2023-09-01T16:43:18Z

Pull driver core updates from Greg KH: "Here is a small set of driver core updates and additions for 6.6-rc1. Included in here are: - stable kernel documentation updates - class structure const work from Ivan on various subsystems - kernfs tweaks - driver core tests! - kobject sanity cleanups - kobject structure reordering to save space - driver core error code handling fixups - other minor driver core cleanups All of these have been in linux-next for a while with no reported problems" * tag 'driver-core-6.6-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (32 commits) driver core: Call in reversed order in device_platform_notify_remove() driver core: Return proper error code when dev_set_name() fails kobject: Remove redundant checks for whether ktype is NULL kobject: Add sanity check for kset->kobj.ktype in kset_register() drivers: base: test: Add missing MODULE_* macros to root device tests drivers: base: test: Add missing MODULE_* macros for platform devices tests drivers: base: Free devm resources when unregistering a device drivers: base: Add basic devm tests for platform devices drivers: base: Add basic devm tests for root devices kernfs: fix missing kernfs_iattr_rwsem locking docs: stable-kernel-rules: mention that regressions must be prevented docs: stable-kernel-rules: fine-tune various details docs: stable-kernel-rules: make the examples for option 1 a proper list docs: stable-kernel-rules: move text around to improve flow docs: stable-kernel-rules: improve structure by changing headlines base/node: Remove duplicated include kernfs: attach uuid for every kernfs and report it in fsid kernfs: add stub helper for kernfs_generic_poll() x86/resctrl: make pseudo_lock_class a static const structure x86/MSR: make msr_class a static const structure ...

Merge tag 'mm-nonmm-stable-2023-08-28-22-48' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2023-08-29T21:53:51Z

Pull non-MM updates from Andrew Morton: - An extensive rework of kexec and crash Kconfig from Eric DeVolder ("refactor Kconfig to consolidate KEXEC and CRASH options") - kernel.h slimming work from Andy Shevchenko ("kernel.h: Split out a couple of macros to args.h") - gdb feature work from Kuan-Ying Lee ("Add GDB memory helper commands") - vsprintf inclusion rationalization from Andy Shevchenko ("lib/vsprintf: Rework header inclusions") - Switch the handling of kdump from a udev scheme to in-kernel handling, by Eric DeVolder ("crash: Kernel handling of CPU and memory hot un/plug") - Many singleton patches to various parts of the tree * tag 'mm-nonmm-stable-2023-08-28-22-48' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (81 commits) document while_each_thread(), change first_tid() to use for_each_thread() drivers/char/mem.c: shrink character device's devlist[] array x86/crash: optimize CPU changes crash: change crash_prepare_elf64_headers() to for_each_possible_cpu() crash: hotplug support for kexec_load() x86/crash: add x86 crash hotplug support crash: memory and CPU hotplug sysfs attributes kexec: exclude elfcorehdr from the segment digest crash: add generic infrastructure for crash hotplug support crash: move a few code bits to setup support of crash hotplug kstrtox: consistently use _tolower() kill do_each_thread() nilfs2: fix WARNING in mark_buffer_dirty due to discarded buffer reuse scripts/bloat-o-meter: count weak symbol sizes treewide: drop CONFIG_EMBEDDED lockdep: fix static memory detection even more lib/vsprintf: declare no_hash_pointers in sprintf.h lib/vsprintf: split out sprintf() and friends kernel/fork: stop playing lockless games for exe_file replacement adfs: delete unused "union adfs_dirtail" definition ...

crash: memory and CPU hotplug sysfs attributes

2023-08-24T23:25:14Z

Introduce the crash_hotplug attribute for memory and CPUs for use by userspace. These attributes directly facilitate the udev rule for managing userspace re-loading of the crash kernel upon hot un/plug changes. For memory, expose the crash_hotplug attribute to the /sys/devices/system/memory directory. For example: # udevadm info --attribute-walk /sys/devices/system/memory/memory81 looking at device '/devices/system/memory/memory81': KERNEL=="memory81" SUBSYSTEM=="memory" DRIVER=="" ATTR{online}=="1" ATTR{phys_device}=="0" ATTR{phys_index}=="00000051" ATTR{removable}=="1" ATTR{state}=="online" ATTR{valid_zones}=="Movable" looking at parent device '/devices/system/memory': KERNELS=="memory" SUBSYSTEMS=="" DRIVERS=="" ATTRS{auto_online_blocks}=="offline" ATTRS{block_size_bytes}=="8000000" ATTRS{crash_hotplug}=="1" For CPUs, expose the crash_hotplug attribute to the /sys/devices/system/cpu directory. For example: # udevadm info --attribute-walk /sys/devices/system/cpu/cpu0 looking at device '/devices/system/cpu/cpu0': KERNEL=="cpu0" SUBSYSTEM=="cpu" DRIVER=="processor" ATTR{crash_notes}=="277c38600" ATTR{crash_notes_size}=="368" ATTR{online}=="1" looking at parent device '/devices/system/cpu': KERNELS=="cpu" SUBSYSTEMS=="" DRIVERS=="" ATTRS{crash_hotplug}=="1" ATTRS{isolated}=="" ATTRS{kernel_max}=="8191" ATTRS{nohz_full}==" (null)" ATTRS{offline}=="4-7" ATTRS{online}=="0-3" ATTRS{possible}=="0-7" ATTRS{present}=="0-3" With these sysfs attributes in place, it is possible to efficiently instruct the udev rule to skip crash kernel reloading for kernels configured with crash hotplug support. For example, the following is the proposed udev rule change for RHEL system 98-kexec.rules (as the first lines of the rule file): # The kernel updates the crash elfcorehdr for CPU and memory changes SUBSYSTEM=="cpu", ATTRS{crash_hotplug}=="1", GOTO="kdump_reload_end" SUBSYSTEM=="memory", ATTRS{crash_hotplug}=="1", GOTO="kdump_reload_end" When examined in the context of 98-kexec.rules, the above rules test if crash_hotplug is set, and if so, the userspace initiated unload-then-reload of the crash kernel is skipped. CPU and memory checks are separated in accordance with CONFIG_HOTPLUG_CPU and CONFIG_MEMORY_HOTPLUG kernel config options. If an architecture supports, for example, memory hotplug but not CPU hotplug, then the /sys/devices/system/memory/crash_hotplug attribute file is present, but the /sys/devices/system/cpu/crash_hotplug attribute file will NOT be present. Thus the udev rule skips userspace processing of memory hot un/plug events, but the udev rule will evaluate false for CPU events, thus allowing userspace to process CPU hot un/plug events (ie the unload-then-reload of the kdump capture kernel). Link: https://lkml.kernel.org/r/20230814214446.6659-5-eric.devolder@oracle.com Signed-off-by: Eric DeVolder Reviewed-by: Sourabh Jain Acked-by: Hari Bathini Acked-by: Baoquan He Cc: Akhil Raj Cc: Bjorn Helgaas Cc: Borislav Petkov (AMD) Cc: Boris Ostrovsky Cc: Dave Hansen Cc: Dave Young Cc: David Hildenbrand Cc: Eric W. Biederman Cc: Greg Kroah-Hartman Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Jonathan Corbet Cc: Konrad Rzeszutek Wilk Cc: Mimi Zohar Cc: Naveen N. Rao Cc: Oscar Salvador Cc: "Rafael J. Wysocki" Cc: Sean Christopherson Cc: Takashi Iwai Cc: Thomas Gleixner Cc: Thomas Weißschuh Cc: Valentin Schneider Cc: Vivek Goyal Cc: Vlastimil Babka Signed-off-by: Andrew Morton

driver core: cpu: Fix the fallback cpu_show_gds() name

2023-08-11T18:36:02Z

In 6524c798b727 ("driver core: cpu: Make cpu_show_not_affected() static") I fat-fingered the name of cpu_show_gds(). Usually, I'd rebase but since those are extraordinary embargoed times, the commit above was already pulled into another tree so no no. Therefore, fix it ontop. Fixes: 6524c798b727 ("driver core: cpu: Make cpu_show_not_affected() static") Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/20230811095831.27513-1-bp@alien8.de

driver core: cpu: Make cpu_show_not_affected() static

2023-08-10T11:25:12Z

Fix a -Wmissing-prototypes warning and add the gather_data_sampling() stub macro call for real. Fixes: 0fddfe338210 ("driver core: cpu: Unify redundant silly stubs") Closes: https://lore.kernel.org/oe-kbuild-all/202308101956.oRj1ls7s-lkp@intel.com Reported-by: kernel test robot Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/202308101956.oRj1ls7s-lkp@intel.com

driver core: cpu: Unify redundant silly stubs

2023-08-10T09:03:04Z

Make them all a weak function, aliasing to a single function which issues the "Not affected" string. No functional changes. Suggested-by: Linus Torvalds Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Greg Kroah-Hartman Reviewed-by: Nikolay Borisov Link: https://lore.kernel.org/r/20230809102700.29449-3-bp@alien8.de

Merge tag 'gds-for-linus-2023-08-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2023-08-08T00:03:54Z

Pull x86/gds fixes from Dave Hansen: "Mitigate Gather Data Sampling issue: - Add Base GDS mitigation - Support GDS_NO under KVM - Fix a documentation typo" * tag 'gds-for-linus-2023-08-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: Documentation/x86: Fix backwards on/off logic about YMM support KVM: Add GDS_NO support to KVM x86/speculation: Add Kconfig option for GDS x86/speculation: Add force option to GDS mitigation x86/speculation: Add Gather Data Sampling mitigation

driver/base/cpu: Retry online operation if -EBUSY

2023-08-05T06:31:41Z

Booting the kernel with "maxcpus=1" is a common technique for CPU partitioning and isolation. It delays the CPU bringup process until when the bootup scripts are ready to bring CPUs online by writing 1 to /sys/device/system/cpu/cpu/online. However, it was found that not all the CPUs were online after bootup. The collection of offline CPUs are different after every reboot. Further investigation reveals that some "online" write operations fail with an -EBUSY error. This error is returned when CPU hotplug is temporiarly disabled when cpu_hotplug_disable() is called. During bootup, the main caller of cpu_hotplug_disable() is pci_call_probe() for PCI device initialization. By measuring the times spent with cpu_hotplug_disabled set in a typical 2-socket server, most of them last less than 10ms. However, there are a few that can last hundreds of ms. Note that the cpu_hotplug_disabled period of different devices can overlap leading to longer cpu_hotplug_disabled hold time. Since the CPU hotplug disable condition is transient and it is not that easy to modify all the existing bootup scripts to handle this condition, the kernel can help by retrying the online operation when an -EBUSY error is returned. This patch retries the online operation in cpu_subsys_online() when an -EBUSY error is returned for up to 5 times after an exponentially increasing delay that can last a total of at least 620ms of waiting time by calling msleep(). With this patch in place, booting up the patched kernel with "maxcpus=1" does not leave any CPU in an offline state in 10 reboot attempts. Reported-by: Vishal Agrawal Signed-off-by: Waiman Long Link: https://lore.kernel.org/r/20230724143826.3996163-1-longman@redhat.com Signed-off-by: Greg Kroah-Hartman

x86/srso: Add a Speculative RAS Overflow mitigation

2023-07-27T09:07:14Z

Add a mitigation for the speculative return address stack overflow vulnerability found on AMD processors. The mitigation works by ensuring all RET instructions speculate to a controlled location, similar to how speculation is controlled in the retpoline sequence. To accomplish this, the __x86_return_thunk forces the CPU to mispredict every function return using a 'safe return' sequence. To ensure the safety of this mitigation, the kernel must ensure that the safe return sequence is itself free from attacker interference. In Zen3 and Zen4, this is accomplished by creating a BTB alias between the untraining function srso_untrain_ret_alias() and the safe return function srso_safe_ret_alias() which results in evicting a potentially poisoned BTB entry and using that safe one for all function returns. In older Zen1 and Zen2, this is accomplished using a reinterpretation technique similar to Retbleed one: srso_untrain_ret() and srso_safe_ret(). Signed-off-by: Borislav Petkov (AMD)