user/sven/linux.git/include/linux/cpu.h, branch v6.1.87

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

2024-03-15T14:48:21Z

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

x86/speculation: Add cpu_show_gds() prototype

2023-08-16T16:27:25Z

commit a57c27c7ad85c420b7de44c6ee56692d51709dda upstream. 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 Signed-off-by: Greg Kroah-Hartman

x86/srso: Add a Speculative RAS Overflow mitigation

2023-08-08T18:03:50Z

Upstream commit: fb3bd914b3ec28f5fb697ac55c4846ac2d542855 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) Signed-off-by: Greg Kroah-Hartman

init: Provide arch_cpu_finalize_init()

2023-08-08T18:03:46Z

commit 7725acaa4f0c04fbefb0e0d342635b967bb7d414 upstream check_bugs() has become a dumping ground for all sorts of activities to finalize the CPU initialization before running the rest of the init code. Most are empty, a few do actual bug checks, some do alternative patching and some cobble a CPU advertisement string together.... Aside of that the current implementation requires duplicated function declaration and mostly empty header files for them. Provide a new function arch_cpu_finalize_init(). Provide a generic declaration if CONFIG_ARCH_HAS_CPU_FINALIZE_INIT is selected and a stub inline otherwise. This requires a temporary #ifdef in start_kernel() which will be removed along with check_bugs() once the architectures are converted over. Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20230613224544.957805717@linutronix.de Signed-off-by: Daniel Sneddon Signed-off-by: Greg Kroah-Hartman

x86/bugs: Report AMD retbleed vulnerability

2022-06-27T08:33:59Z

Report that AMD x86 CPUs are vulnerable to the RETBleed (Arbitrary Speculative Code Execution with Return Instructions) attack. [peterz: add hygon] [kim: invert parity; fam15h] Co-developed-by: Kim Phillips Signed-off-by: Kim Phillips Signed-off-by: Alexandre Chartre Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Borislav Petkov Reviewed-by: Josh Poimboeuf Signed-off-by: Borislav Petkov

x86/speculation/mmio: Add sysfs reporting for Processor MMIO Stale Data

2022-05-21T10:16:04Z

Add the sysfs reporting file for Processor MMIO Stale Data vulnerability. It exposes the vulnerability and mitigation state similar to the existing files for the other hardware vulnerabilities. Signed-off-by: Pawan Gupta Signed-off-by: Borislav Petkov

x86,objtool: Mark cpu_startup_entry() __noreturn

2022-04-19T19:58:48Z

GCC-8 isn't clever enough to figure out that cpu_start_entry() is a noreturn while objtool is. This results in code after the call in start_secondary(). Give GCC a hand so that they all agree on things. vmlinux.o: warning: objtool: start_secondary()+0x10e: unreachable Reported-by: Rick Edgecombe Signed-off-by: Peter Zijlstra (Intel) Acked-by: Josh Poimboeuf Link: https://lore.kernel.org/r/20220408094718.383658532@infradead.org

cpu/hotplug: Remove deprecated CPU-hotplug functions.

2021-09-10T22:41:21Z

No users in tree use the deprecated CPU-hotplug functions anymore. Remove them. Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20210803141621.780504-39-bigeasy@linutronix.de

cpu/hotplug: Fix build error of using {add,remove}_cpu() with !CONFIG_SMP

2021-03-10T08:16:09Z

279dcf693ac7 ("virt: acrn: Introduce an interface for Service VM to control vCPU") introduced {add,remove}_cpu() usage and it hit below error with !CONFIG_SMP: ../drivers/virt/acrn/hsm.c: In function ‘remove_cpu_store’: ../drivers/virt/acrn/hsm.c:389:3: error: implicit declaration of function ‘remove_cpu’; [-Werror=implicit-function-declaration] remove_cpu(cpu); ../drivers/virt/acrn/hsm.c:402:2: error: implicit declaration of function ‘add_cpu’; [-Werror=implicit-function-declaration] add_cpu(cpu); Add add_cpu() function prototypes with !CONFIG_SMP and remove_cpu() with !CONFIG_HOTPLUG_CPU for such usage. Fixes: 279dcf693ac7 ("virt: acrn: Introduce an interface for Service VM to control vCPU") Cc: Stephen Rothwell Cc: Thomas Gleixner Cc: Greg Kroah-Hartman Cc: Qais Yousef Reported-by: Randy Dunlap Reviewed-by: Qais Yousef Acked-by: Randy Dunlap # build-tested Signed-off-by: Shuo Liu Link: https://lore.kernel.org/r/20210221134339.57851-1-shuo.a.liu@intel.com Signed-off-by: Greg Kroah-Hartman

cpu/hotplug: Add lockdep_is_cpus_held()

2021-01-07T00:24:59Z

This commit adds a lockdep_is_cpus_held() function to verify that the proper locks are held and that various operations are running in the correct context. Signed-off-by: Frederic Weisbecker Cc: Paul E. McKenney Cc: Josh Triplett Cc: Steven Rostedt Cc: Mathieu Desnoyers Cc: Lai Jiangshan Cc: Joel Fernandes Cc: Neeraj Upadhyay Cc: Thomas Gleixner Cc: Boqun Feng Signed-off-by: Paul E. McKenney