linux-stable.git/include/linux/cpu.h, branch v6.8.4

x86/rfds: Mitigate Register File Data Sampling (RFDS)

2024-03-15T14:48:13+00:00

commit 8076fcde016c9c0e0660543e67bff86cb48a7c9c upstream.

RFDS is a CPU vulnerability that may allow userspace to infer kernel
stale data previously used in floating point registers, vector registers
and integer registers. RFDS only affects certain Intel Atom processors.

Intel released a microcode update that uses VERW instruction to clear
the affected CPU buffers. Unlike MDS, none of the affected cores support
SMT.

Add RFDS bug infrastructure and enable the VERW based mitigation by
default, that clears the affected buffers just before exiting to
userspace. Also add sysfs reporting and cmdline parameter
"reg_file_data_sampling" to control the mitigation.

For details see:
Documentation/admin-guide/hw-vuln/reg-file-data-sampling.rst

Signed-off-by: Pawan Gupta 
Signed-off-by: Dave Hansen 
Reviewed-by: Thomas Gleixner 
Acked-by: Josh Poimboeuf 
Signed-off-by: Greg Kroah-Hartman

drivers: base: add arch_cpu_is_hotpluggable()

2023-12-06T03:41:48+00:00

The differences between architecture specific implementations of
arch_register_cpu() are down to whether the CPU is hotpluggable or not.
Rather than overriding the weak version of arch_register_cpu(), provide
a function that can be used to provide this detail instead.

Reviewed-by: Shaoqin Huang 
Signed-off-by: "Russell King (Oracle)" 
Reviewed-by: Jonathan Cameron 
Reviewed-by: Gavin Shan 
Reviewed-by: Thomas Gleixner 
Link: https://lore.kernel.org/r/E1r5R3M-00CszH-6r@rmk-PC.armlinux.org.uk
Signed-off-by: Greg Kroah-Hartman

drivers: base: Allow parts of GENERIC_CPU_DEVICES to be overridden

2023-12-06T03:41:48+00:00

Architectures often have extra per-cpu work that needs doing
before a CPU is registered, often to determine if a CPU is
hotpluggable.

To allow the ACPI architectures to use GENERIC_CPU_DEVICES, move
the cpu_register() call into arch_register_cpu(), which is made __weak
so architectures with extra work can override it.
This aligns with the way x86, ia64 and loongarch register hotplug CPUs
when they become present.

Signed-off-by: James Morse 
Reviewed-by: Shaoqin Huang 
Reviewed-by: Gavin Shan 
Signed-off-by: "Russell King (Oracle)" 
Reviewed-by: Jonathan Cameron 
Reviewed-by: Thomas Gleixner 
Link: https://lore.kernel.org/r/E1r5R3B-00Csz6-Uh@rmk-PC.armlinux.org.uk
Signed-off-by: Greg Kroah-Hartman

Merge tag 'v6.6-rc7' into sched/core, to pick up fixes

2023-10-23T09:32:25+00:00

Pick up recent sched/urgent fixes merged upstream.

Signed-off-by: Ingo Molnar

cpu-hotplug: Provide prototypes for arch CPU registration

2023-10-11T12:27:37+00:00

Provide common prototypes for arch_register_cpu() and
arch_unregister_cpu(). These are called by acpi_processor.c, with weak
versions, so the prototype for this is already set. It is generally not
necessary for function prototypes to be conditional on preprocessor macros.

Some architectures (e.g. Loongarch) are missing the prototype for this, and
rather than add it to Loongarch's asm/cpu.h, do the job once for everyone.

Since this covers everyone, remove the now unnecessary prototypes in
asm/cpu.h, and therefore remove the 'static' from one of ia64's
arch_register_cpu() definitions.

[ tglx: Bring back the ia64 part and remove the ACPI prototypes ]

Signed-off-by: Russell King (Oracle) 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/r/E1qkoRr-0088Q8-Da@rmk-PC.armlinux.org.uk

sched: Simplify tg_set_cfs_bandwidth()

2023-09-13T13:01:42+00:00

Use guards to reduce gotos and simplify control flow.

Signed-off-by: Peter Zijlstra (Intel) 
Signed-off-by: Ingo Molnar

Merge tag 'smp-core-2023-08-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2023-08-28T22:04:43+00:00

Pull CPU hotplug updates from Thomas Gleixner:
 "Updates for the CPU hotplug core:

   - Support partial SMT enablement.

     So far the sysfs SMT control only allows to toggle between SMT on
     and off. That's sufficient for x86 which usually has at max two
     threads except for the Xeon PHI platform which has four threads per
     core

     Though PowerPC has up to 16 threads per core and so far it's only
     possible to control the number of enabled threads per core via a
     command line option. There is some way to control this at runtime,
     but that lacks enforcement and the usability is awkward

     This update expands the sysfs interface and the core infrastructure
     to accept numerical values so PowerPC can build SMT runtime control
     for partial SMT enablement on top

     The core support has also been provided to the PowerPC maintainers
     who added the PowerPC related changes on top

   - Minor cleanups and documentation updates"

* tag 'smp-core-2023-08-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  Documentation: core-api/cpuhotplug: Fix state names
  cpu/hotplug: Remove unused function declaration cpu_set_state_online()
  cpu/SMT: Fix cpu_smt_possible() comment
  cpu/SMT: Allow enabling partial SMT states via sysfs
  cpu/SMT: Create topology_smt_thread_allowed()
  cpu/SMT: Remove topology_smt_supported()
  cpu/SMT: Store the current/max number of threads
  cpu/SMT: Move smt/control simple exit cases earlier
  cpu/SMT: Move SMT prototypes into cpu_smt.h
  cpu/hotplug: Remove dependancy against cpu_primary_thread_mask

x86/speculation: Add cpu_show_gds() prototype

2023-08-10T16:12:18+00:00

The newly added function has two definitions but no prototypes:

drivers/base/cpu.c:605:16: error: no previous prototype for 'cpu_show_gds' [-Werror=missing-prototypes]

Add a declaration next to the other ones for this file to avoid the
warning.

Fixes: 8974eb588283b ("x86/speculation: Add Gather Data Sampling mitigation")
Signed-off-by: Arnd Bergmann 
Signed-off-by: Dave Hansen 
Tested-by: Daniel Sneddon 
Cc: stable@kernel.org
Link: https://lore.kernel.org/all/20230809130530.1913368-1-arnd%40kernel.org

cpu/hotplug: Remove unused function declaration cpu_set_state_online()

2023-08-07T16:22:42+00:00

Commit 5356297d12d9 ("cpu/hotplug: Remove cpu_report_state() and related unused cruft")
removed function but leave the declaration.

Signed-off-by: Yue Haibing 
Signed-off-by: Thomas Gleixner 
Link: https://lore.kernel.org/r/20230805110406.45900-1-yuehaibing@huawei.com

cpu/SMT: Move SMT prototypes into cpu_smt.h

2023-07-28T07:53:36+00:00

In order to export the cpuhp_smt_control enum as part of the interface
between generic and architecture code, the architecture code needs to
include asm/topology.h.

But that leads to circular header dependencies. So split the enum and
related declarations into a separate header.

[ ldufour: Reworded the commit's description ]

Signed-off-by: Michael Ellerman 
Signed-off-by: Laurent Dufour 
Signed-off-by: Thomas Gleixner 
Tested-by: Zhang Rui 
Link: https://lore.kernel.org/r/20230705145143.40545-3-ldufour@linux.ibm.com