| // SPDX-License-Identifier: GPL-2.0-or-later |
| /* KVM paravirtual clock driver. A clocksource implementation |
| Copyright (C) 2008 Glauber de Oliveira Costa, Red Hat Inc. |
| */ |
| |
| #include <linux/clocksource.h> |
| #include <linux/kvm_para.h> |
| #include <asm/pvclock.h> |
| #include <asm/msr.h> |
| #include <asm/apic.h> |
| #include <linux/percpu.h> |
| #include <linux/hardirq.h> |
| #include <linux/cpuhotplug.h> |
| #include <linux/sched.h> |
| #include <linux/sched/clock.h> |
| #include <linux/mm.h> |
| #include <linux/slab.h> |
| #include <linux/set_memory.h> |
| |
| #include <asm/hypervisor.h> |
| #include <asm/mem_encrypt.h> |
| #include <asm/x86_init.h> |
| #include <asm/kvmclock.h> |
| |
| static int kvmclock __initdata = 1; |
| static int kvmclock_vsyscall __initdata = 1; |
| static int msr_kvm_system_time __ro_after_init = MSR_KVM_SYSTEM_TIME; |
| static int msr_kvm_wall_clock __ro_after_init = MSR_KVM_WALL_CLOCK; |
| static u64 kvm_sched_clock_offset __ro_after_init; |
| |
| static int __init parse_no_kvmclock(char *arg) |
| { |
| kvmclock = 0; |
| return 0; |
| } |
| early_param("no-kvmclock", parse_no_kvmclock); |
| |
| static int __init parse_no_kvmclock_vsyscall(char *arg) |
| { |
| kvmclock_vsyscall = 0; |
| return 0; |
| } |
| early_param("no-kvmclock-vsyscall", parse_no_kvmclock_vsyscall); |
| |
| /* Aligned to page sizes to match whats mapped via vsyscalls to userspace */ |
| #define HV_CLOCK_SIZE (sizeof(struct pvclock_vsyscall_time_info) * NR_CPUS) |
| #define HVC_BOOT_ARRAY_SIZE \ |
| (PAGE_SIZE / sizeof(struct pvclock_vsyscall_time_info)) |
| |
| static struct pvclock_vsyscall_time_info |
| hv_clock_boot[HVC_BOOT_ARRAY_SIZE] __bss_decrypted __aligned(PAGE_SIZE); |
| static struct pvclock_wall_clock wall_clock __bss_decrypted; |
| static DEFINE_PER_CPU(struct pvclock_vsyscall_time_info *, hv_clock_per_cpu); |
| static struct pvclock_vsyscall_time_info *hvclock_mem; |
| |
| static inline struct pvclock_vcpu_time_info *this_cpu_pvti(void) |
| { |
| return &this_cpu_read(hv_clock_per_cpu)->pvti; |
| } |
| |
| static inline struct pvclock_vsyscall_time_info *this_cpu_hvclock(void) |
| { |
| return this_cpu_read(hv_clock_per_cpu); |
| } |
| |
| /* |
| * The wallclock is the time of day when we booted. Since then, some time may |
| * have elapsed since the hypervisor wrote the data. So we try to account for |
| * that with system time |
| */ |
| static void kvm_get_wallclock(struct timespec64 *now) |
| { |
| wrmsrl(msr_kvm_wall_clock, slow_virt_to_phys(&wall_clock)); |
| preempt_disable(); |
| pvclock_read_wallclock(&wall_clock, this_cpu_pvti(), now); |
| preempt_enable(); |
| } |
| |
| static int kvm_set_wallclock(const struct timespec64 *now) |
| { |
| return -ENODEV; |
| } |
| |
| static u64 kvm_clock_read(void) |
| { |
| u64 ret; |
| |
| preempt_disable_notrace(); |
| ret = pvclock_clocksource_read(this_cpu_pvti()); |
| preempt_enable_notrace(); |
| return ret; |
| } |
| |
| static u64 kvm_clock_get_cycles(struct clocksource *cs) |
| { |
| return kvm_clock_read(); |
| } |
| |
| static u64 kvm_sched_clock_read(void) |
| { |
| return kvm_clock_read() - kvm_sched_clock_offset; |
| } |
| |
| static inline void kvm_sched_clock_init(bool stable) |
| { |
| if (!stable) |
| clear_sched_clock_stable(); |
| kvm_sched_clock_offset = kvm_clock_read(); |
| pv_ops.time.sched_clock = kvm_sched_clock_read; |
| |
| pr_info("kvm-clock: using sched offset of %llu cycles", |
| kvm_sched_clock_offset); |
| |
| BUILD_BUG_ON(sizeof(kvm_sched_clock_offset) > |
| sizeof(((struct pvclock_vcpu_time_info *)NULL)->system_time)); |
| } |
| |
| /* |
| * If we don't do that, there is the possibility that the guest |
| * will calibrate under heavy load - thus, getting a lower lpj - |
| * and execute the delays themselves without load. This is wrong, |
| * because no delay loop can finish beforehand. |
| * Any heuristics is subject to fail, because ultimately, a large |
| * poll of guests can be running and trouble each other. So we preset |
| * lpj here |
| */ |
| static unsigned long kvm_get_tsc_khz(void) |
| { |
| setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ); |
| return pvclock_tsc_khz(this_cpu_pvti()); |
| } |
| |
| static void __init kvm_get_preset_lpj(void) |
| { |
| unsigned long khz; |
| u64 lpj; |
| |
| khz = kvm_get_tsc_khz(); |
| |
| lpj = ((u64)khz * 1000); |
| do_div(lpj, HZ); |
| preset_lpj = lpj; |
| } |
| |
| bool kvm_check_and_clear_guest_paused(void) |
| { |
| struct pvclock_vsyscall_time_info *src = this_cpu_hvclock(); |
| bool ret = false; |
| |
| if (!src) |
| return ret; |
| |
| if ((src->pvti.flags & PVCLOCK_GUEST_STOPPED) != 0) { |
| src->pvti.flags &= ~PVCLOCK_GUEST_STOPPED; |
| pvclock_touch_watchdogs(); |
| ret = true; |
| } |
| return ret; |
| } |
| |
| struct clocksource kvm_clock = { |
| .name = "kvm-clock", |
| .read = kvm_clock_get_cycles, |
| .rating = 400, |
| .mask = CLOCKSOURCE_MASK(64), |
| .flags = CLOCK_SOURCE_IS_CONTINUOUS, |
| }; |
| EXPORT_SYMBOL_GPL(kvm_clock); |
| |
| static void kvm_register_clock(char *txt) |
| { |
| struct pvclock_vsyscall_time_info *src = this_cpu_hvclock(); |
| u64 pa; |
| |
| if (!src) |
| return; |
| |
| pa = slow_virt_to_phys(&src->pvti) | 0x01ULL; |
| wrmsrl(msr_kvm_system_time, pa); |
| pr_info("kvm-clock: cpu %d, msr %llx, %s", smp_processor_id(), pa, txt); |
| } |
| |
| static void kvm_save_sched_clock_state(void) |
| { |
| } |
| |
| static void kvm_restore_sched_clock_state(void) |
| { |
| kvm_register_clock("primary cpu clock, resume"); |
| } |
| |
| #ifdef CONFIG_X86_LOCAL_APIC |
| static void kvm_setup_secondary_clock(void) |
| { |
| kvm_register_clock("secondary cpu clock"); |
| } |
| #endif |
| |
| void kvmclock_disable(void) |
| { |
| native_write_msr(msr_kvm_system_time, 0, 0); |
| } |
| |
| static void __init kvmclock_init_mem(void) |
| { |
| unsigned long ncpus; |
| unsigned int order; |
| struct page *p; |
| int r; |
| |
| if (HVC_BOOT_ARRAY_SIZE >= num_possible_cpus()) |
| return; |
| |
| ncpus = num_possible_cpus() - HVC_BOOT_ARRAY_SIZE; |
| order = get_order(ncpus * sizeof(*hvclock_mem)); |
| |
| p = alloc_pages(GFP_KERNEL, order); |
| if (!p) { |
| pr_warn("%s: failed to alloc %d pages", __func__, (1U << order)); |
| return; |
| } |
| |
| hvclock_mem = page_address(p); |
| |
| /* |
| * hvclock is shared between the guest and the hypervisor, must |
| * be mapped decrypted. |
| */ |
| if (sev_active()) { |
| r = set_memory_decrypted((unsigned long) hvclock_mem, |
| 1UL << order); |
| if (r) { |
| __free_pages(p, order); |
| hvclock_mem = NULL; |
| pr_warn("kvmclock: set_memory_decrypted() failed. Disabling\n"); |
| return; |
| } |
| } |
| |
| memset(hvclock_mem, 0, PAGE_SIZE << order); |
| } |
| |
| static int __init kvm_setup_vsyscall_timeinfo(void) |
| { |
| #ifdef CONFIG_X86_64 |
| u8 flags; |
| |
| if (!per_cpu(hv_clock_per_cpu, 0) || !kvmclock_vsyscall) |
| return 0; |
| |
| flags = pvclock_read_flags(&hv_clock_boot[0].pvti); |
| if (!(flags & PVCLOCK_TSC_STABLE_BIT)) |
| return 0; |
| |
| kvm_clock.archdata.vclock_mode = VCLOCK_PVCLOCK; |
| #endif |
| |
| kvmclock_init_mem(); |
| |
| return 0; |
| } |
| early_initcall(kvm_setup_vsyscall_timeinfo); |
| |
| static int kvmclock_setup_percpu(unsigned int cpu) |
| { |
| struct pvclock_vsyscall_time_info *p = per_cpu(hv_clock_per_cpu, cpu); |
| |
| /* |
| * The per cpu area setup replicates CPU0 data to all cpu |
| * pointers. So carefully check. CPU0 has been set up in init |
| * already. |
| */ |
| if (!cpu || (p && p != per_cpu(hv_clock_per_cpu, 0))) |
| return 0; |
| |
| /* Use the static page for the first CPUs, allocate otherwise */ |
| if (cpu < HVC_BOOT_ARRAY_SIZE) |
| p = &hv_clock_boot[cpu]; |
| else if (hvclock_mem) |
| p = hvclock_mem + cpu - HVC_BOOT_ARRAY_SIZE; |
| else |
| return -ENOMEM; |
| |
| per_cpu(hv_clock_per_cpu, cpu) = p; |
| return p ? 0 : -ENOMEM; |
| } |
| |
| void __init kvmclock_init(void) |
| { |
| u8 flags; |
| |
| if (!kvm_para_available() || !kvmclock) |
| return; |
| |
| if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE2)) { |
| msr_kvm_system_time = MSR_KVM_SYSTEM_TIME_NEW; |
| msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK_NEW; |
| } else if (!kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE)) { |
| return; |
| } |
| |
| if (cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "kvmclock:setup_percpu", |
| kvmclock_setup_percpu, NULL) < 0) { |
| return; |
| } |
| |
| pr_info("kvm-clock: Using msrs %x and %x", |
| msr_kvm_system_time, msr_kvm_wall_clock); |
| |
| this_cpu_write(hv_clock_per_cpu, &hv_clock_boot[0]); |
| kvm_register_clock("primary cpu clock"); |
| pvclock_set_pvti_cpu0_va(hv_clock_boot); |
| |
| if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE_STABLE_BIT)) |
| pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT); |
| |
| flags = pvclock_read_flags(&hv_clock_boot[0].pvti); |
| kvm_sched_clock_init(flags & PVCLOCK_TSC_STABLE_BIT); |
| |
| x86_platform.calibrate_tsc = kvm_get_tsc_khz; |
| x86_platform.calibrate_cpu = kvm_get_tsc_khz; |
| x86_platform.get_wallclock = kvm_get_wallclock; |
| x86_platform.set_wallclock = kvm_set_wallclock; |
| #ifdef CONFIG_X86_LOCAL_APIC |
| x86_cpuinit.early_percpu_clock_init = kvm_setup_secondary_clock; |
| #endif |
| x86_platform.save_sched_clock_state = kvm_save_sched_clock_state; |
| x86_platform.restore_sched_clock_state = kvm_restore_sched_clock_state; |
| kvm_get_preset_lpj(); |
| |
| /* |
| * X86_FEATURE_NONSTOP_TSC is TSC runs at constant rate |
| * with P/T states and does not stop in deep C-states. |
| * |
| * Invariant TSC exposed by host means kvmclock is not necessary: |
| * can use TSC as clocksource. |
| * |
| */ |
| if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC) && |
| boot_cpu_has(X86_FEATURE_NONSTOP_TSC) && |
| !check_tsc_unstable()) |
| kvm_clock.rating = 299; |
| |
| clocksource_register_hz(&kvm_clock, NSEC_PER_SEC); |
| pv_info.name = "KVM"; |
| } |