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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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![Linus Torvalds](/assets/img/avatar_default.png)
Merge L1 Terminal Fault fixes from Thomas Gleixner: "L1TF, aka L1 Terminal Fault, is yet another speculative hardware engineering trainwreck. It's a hardware vulnerability which allows unprivileged speculative access to data which is available in the Level 1 Data Cache when the page table entry controlling the virtual address, which is used for the access, has the Present bit cleared or other reserved bits set. If an instruction accesses a virtual address for which the relevant page table entry (PTE) has the Present bit cleared or other reserved bits set, then speculative execution ignores the invalid PTE and loads the referenced data if it is present in the Level 1 Data Cache, as if the page referenced by the address bits in the PTE was still present and accessible. While this is a purely speculative mechanism and the instruction will raise a page fault when it is retired eventually, the pure act of loading the data and making it available to other speculative instructions opens up the opportunity for side channel attacks to unprivileged malicious code, similar to the Meltdown attack. While Meltdown breaks the user space to kernel space protection, L1TF allows to attack any physical memory address in the system and the attack works across all protection domains. It allows an attack of SGX and also works from inside virtual machines because the speculation bypasses the extended page table (EPT) protection mechanism. The assoicated CVEs are: CVE-2018-3615, CVE-2018-3620, CVE-2018-3646 The mitigations provided by this pull request include: - Host side protection by inverting the upper address bits of a non present page table entry so the entry points to uncacheable memory. - Hypervisor protection by flushing L1 Data Cache on VMENTER. - SMT (HyperThreading) control knobs, which allow to 'turn off' SMT by offlining the sibling CPU threads. The knobs are available on the kernel command line and at runtime via sysfs - Control knobs for the hypervisor mitigation, related to L1D flush and SMT control. The knobs are available on the kernel command line and at runtime via sysfs - Extensive documentation about L1TF including various degrees of mitigations. Thanks to all people who have contributed to this in various ways - patches, review, testing, backporting - and the fruitful, sometimes heated, but at the end constructive discussions. There is work in progress to provide other forms of mitigations, which might be less horrible performance wise for a particular kind of workloads, but this is not yet ready for consumption due to their complexity and limitations" * 'l1tf-final' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (75 commits) x86/microcode: Allow late microcode loading with SMT disabled tools headers: Synchronise x86 cpufeatures.h for L1TF additions x86/mm/kmmio: Make the tracer robust against L1TF x86/mm/pat: Make set_memory_np() L1TF safe x86/speculation/l1tf: Make pmd/pud_mknotpresent() invert x86/speculation/l1tf: Invert all not present mappings cpu/hotplug: Fix SMT supported evaluation KVM: VMX: Tell the nested hypervisor to skip L1D flush on vmentry x86/speculation: Use ARCH_CAPABILITIES to skip L1D flush on vmentry x86/speculation: Simplify sysfs report of VMX L1TF vulnerability Documentation/l1tf: Remove Yonah processors from not vulnerable list x86/KVM/VMX: Don't set l1tf_flush_l1d from vmx_handle_external_intr() x86/irq: Let interrupt handlers set kvm_cpu_l1tf_flush_l1d x86: Don't include linux/irq.h from asm/hardirq.h x86/KVM/VMX: Introduce per-host-cpu analogue of l1tf_flush_l1d x86/irq: Demote irq_cpustat_t::__softirq_pending to u16 x86/KVM/VMX: Move the l1tf_flush_l1d test to vmx_l1d_flush() x86/KVM/VMX: Replace 'vmx_l1d_flush_always' with 'vmx_l1d_flush_cond' x86/KVM/VMX: Don't set l1tf_flush_l1d to true from vmx_l1d_flush() cpu/hotplug: detect SMT disabled by BIOS ...
190 lines
5.9 KiB
C
190 lines
5.9 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* include/linux/cpu.h - generic cpu definition
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*
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* This is mainly for topological representation. We define the
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* basic 'struct cpu' here, which can be embedded in per-arch
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* definitions of processors.
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*
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* Basic handling of the devices is done in drivers/base/cpu.c
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*
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* CPUs are exported via sysfs in the devices/system/cpu
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* directory.
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*/
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#ifndef _LINUX_CPU_H_
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#define _LINUX_CPU_H_
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#include <linux/node.h>
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#include <linux/compiler.h>
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#include <linux/cpumask.h>
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#include <linux/cpuhotplug.h>
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struct device;
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struct device_node;
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struct attribute_group;
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struct cpu {
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int node_id; /* The node which contains the CPU */
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int hotpluggable; /* creates sysfs control file if hotpluggable */
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struct device dev;
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};
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extern void boot_cpu_init(void);
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extern void boot_cpu_hotplug_init(void);
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extern void cpu_init(void);
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extern void trap_init(void);
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extern int register_cpu(struct cpu *cpu, int num);
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extern struct device *get_cpu_device(unsigned cpu);
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extern bool cpu_is_hotpluggable(unsigned cpu);
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extern bool arch_match_cpu_phys_id(int cpu, u64 phys_id);
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extern bool arch_find_n_match_cpu_physical_id(struct device_node *cpun,
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int cpu, unsigned int *thread);
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extern int cpu_add_dev_attr(struct device_attribute *attr);
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extern void cpu_remove_dev_attr(struct device_attribute *attr);
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extern int cpu_add_dev_attr_group(struct attribute_group *attrs);
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extern void cpu_remove_dev_attr_group(struct attribute_group *attrs);
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extern ssize_t cpu_show_meltdown(struct device *dev,
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struct device_attribute *attr, char *buf);
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extern ssize_t cpu_show_spectre_v1(struct device *dev,
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struct device_attribute *attr, char *buf);
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extern ssize_t cpu_show_spectre_v2(struct device *dev,
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struct device_attribute *attr, char *buf);
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extern ssize_t cpu_show_spec_store_bypass(struct device *dev,
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struct device_attribute *attr, char *buf);
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extern ssize_t cpu_show_l1tf(struct device *dev,
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struct device_attribute *attr, char *buf);
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extern __printf(4, 5)
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struct device *cpu_device_create(struct device *parent, void *drvdata,
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const struct attribute_group **groups,
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const char *fmt, ...);
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#ifdef CONFIG_HOTPLUG_CPU
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extern void unregister_cpu(struct cpu *cpu);
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extern ssize_t arch_cpu_probe(const char *, size_t);
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extern ssize_t arch_cpu_release(const char *, size_t);
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#endif
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/*
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* These states are not related to the core CPU hotplug mechanism. They are
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* used by various (sub)architectures to track internal state
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*/
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#define CPU_ONLINE 0x0002 /* CPU is up */
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#define CPU_UP_PREPARE 0x0003 /* CPU coming up */
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#define CPU_DEAD 0x0007 /* CPU dead */
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#define CPU_DEAD_FROZEN 0x0008 /* CPU timed out on unplug */
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#define CPU_POST_DEAD 0x0009 /* CPU successfully unplugged */
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#define CPU_BROKEN 0x000B /* CPU did not die properly */
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#ifdef CONFIG_SMP
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extern bool cpuhp_tasks_frozen;
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int cpu_up(unsigned int cpu);
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void notify_cpu_starting(unsigned int cpu);
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extern void cpu_maps_update_begin(void);
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extern void cpu_maps_update_done(void);
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#else /* CONFIG_SMP */
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#define cpuhp_tasks_frozen 0
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static inline void cpu_maps_update_begin(void)
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{
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}
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static inline void cpu_maps_update_done(void)
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{
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}
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#endif /* CONFIG_SMP */
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extern struct bus_type cpu_subsys;
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#ifdef CONFIG_HOTPLUG_CPU
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extern void cpus_write_lock(void);
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extern void cpus_write_unlock(void);
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extern void cpus_read_lock(void);
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extern void cpus_read_unlock(void);
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extern void lockdep_assert_cpus_held(void);
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extern void cpu_hotplug_disable(void);
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extern void cpu_hotplug_enable(void);
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void clear_tasks_mm_cpumask(int cpu);
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int cpu_down(unsigned int cpu);
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#else /* CONFIG_HOTPLUG_CPU */
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static inline void cpus_write_lock(void) { }
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static inline void cpus_write_unlock(void) { }
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static inline void cpus_read_lock(void) { }
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static inline void cpus_read_unlock(void) { }
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static inline void lockdep_assert_cpus_held(void) { }
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static inline void cpu_hotplug_disable(void) { }
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static inline void cpu_hotplug_enable(void) { }
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#endif /* !CONFIG_HOTPLUG_CPU */
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/* Wrappers which go away once all code is converted */
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static inline void cpu_hotplug_begin(void) { cpus_write_lock(); }
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static inline void cpu_hotplug_done(void) { cpus_write_unlock(); }
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static inline void get_online_cpus(void) { cpus_read_lock(); }
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static inline void put_online_cpus(void) { cpus_read_unlock(); }
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#ifdef CONFIG_PM_SLEEP_SMP
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extern int freeze_secondary_cpus(int primary);
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static inline int disable_nonboot_cpus(void)
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{
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return freeze_secondary_cpus(0);
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}
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extern void enable_nonboot_cpus(void);
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#else /* !CONFIG_PM_SLEEP_SMP */
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static inline int disable_nonboot_cpus(void) { return 0; }
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static inline void enable_nonboot_cpus(void) {}
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#endif /* !CONFIG_PM_SLEEP_SMP */
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void cpu_startup_entry(enum cpuhp_state state);
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void cpu_idle_poll_ctrl(bool enable);
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/* Attach to any functions which should be considered cpuidle. */
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#define __cpuidle __attribute__((__section__(".cpuidle.text")))
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bool cpu_in_idle(unsigned long pc);
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void arch_cpu_idle(void);
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void arch_cpu_idle_prepare(void);
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void arch_cpu_idle_enter(void);
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void arch_cpu_idle_exit(void);
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void arch_cpu_idle_dead(void);
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int cpu_report_state(int cpu);
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int cpu_check_up_prepare(int cpu);
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void cpu_set_state_online(int cpu);
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void play_idle(unsigned long duration_ms);
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#ifdef CONFIG_HOTPLUG_CPU
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bool cpu_wait_death(unsigned int cpu, int seconds);
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bool cpu_report_death(void);
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void cpuhp_report_idle_dead(void);
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#else
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static inline void cpuhp_report_idle_dead(void) { }
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#endif /* #ifdef CONFIG_HOTPLUG_CPU */
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enum cpuhp_smt_control {
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CPU_SMT_ENABLED,
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CPU_SMT_DISABLED,
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CPU_SMT_FORCE_DISABLED,
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CPU_SMT_NOT_SUPPORTED,
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};
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#if defined(CONFIG_SMP) && defined(CONFIG_HOTPLUG_SMT)
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extern enum cpuhp_smt_control cpu_smt_control;
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extern void cpu_smt_disable(bool force);
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extern void cpu_smt_check_topology_early(void);
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extern void cpu_smt_check_topology(void);
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#else
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# define cpu_smt_control (CPU_SMT_ENABLED)
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static inline void cpu_smt_disable(bool force) { }
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static inline void cpu_smt_check_topology_early(void) { }
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static inline void cpu_smt_check_topology(void) { }
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#endif
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#endif /* _LINUX_CPU_H_ */
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