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https://github.com/edk2-porting/linux-next.git
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b95a8a27c3
Switch to the generic VDSO clock mode storage. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com> (VDSO parts) Acked-by: Juergen Gross <jgross@suse.com> (Xen parts) Acked-by: Paolo Bonzini <pbonzini@redhat.com> (KVM parts) Link: https://lkml.kernel.org/r/20200207124403.152039903@linutronix.de
378 lines
9.5 KiB
C
378 lines
9.5 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/* KVM paravirtual clock driver. A clocksource implementation
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Copyright (C) 2008 Glauber de Oliveira Costa, Red Hat Inc.
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*/
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#include <linux/clocksource.h>
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#include <linux/kvm_para.h>
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#include <asm/pvclock.h>
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#include <asm/msr.h>
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#include <asm/apic.h>
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#include <linux/percpu.h>
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#include <linux/hardirq.h>
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#include <linux/cpuhotplug.h>
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#include <linux/sched.h>
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#include <linux/sched/clock.h>
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/set_memory.h>
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#include <asm/hypervisor.h>
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#include <asm/mem_encrypt.h>
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#include <asm/x86_init.h>
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#include <asm/reboot.h>
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#include <asm/kvmclock.h>
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static int kvmclock __initdata = 1;
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static int kvmclock_vsyscall __initdata = 1;
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static int msr_kvm_system_time __ro_after_init = MSR_KVM_SYSTEM_TIME;
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static int msr_kvm_wall_clock __ro_after_init = MSR_KVM_WALL_CLOCK;
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static u64 kvm_sched_clock_offset __ro_after_init;
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static int __init parse_no_kvmclock(char *arg)
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{
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kvmclock = 0;
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return 0;
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}
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early_param("no-kvmclock", parse_no_kvmclock);
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static int __init parse_no_kvmclock_vsyscall(char *arg)
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{
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kvmclock_vsyscall = 0;
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return 0;
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}
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early_param("no-kvmclock-vsyscall", parse_no_kvmclock_vsyscall);
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/* Aligned to page sizes to match whats mapped via vsyscalls to userspace */
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#define HV_CLOCK_SIZE (sizeof(struct pvclock_vsyscall_time_info) * NR_CPUS)
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#define HVC_BOOT_ARRAY_SIZE \
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(PAGE_SIZE / sizeof(struct pvclock_vsyscall_time_info))
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static struct pvclock_vsyscall_time_info
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hv_clock_boot[HVC_BOOT_ARRAY_SIZE] __bss_decrypted __aligned(PAGE_SIZE);
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static struct pvclock_wall_clock wall_clock __bss_decrypted;
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static DEFINE_PER_CPU(struct pvclock_vsyscall_time_info *, hv_clock_per_cpu);
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static struct pvclock_vsyscall_time_info *hvclock_mem;
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static inline struct pvclock_vcpu_time_info *this_cpu_pvti(void)
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{
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return &this_cpu_read(hv_clock_per_cpu)->pvti;
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}
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static inline struct pvclock_vsyscall_time_info *this_cpu_hvclock(void)
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{
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return this_cpu_read(hv_clock_per_cpu);
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}
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/*
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* The wallclock is the time of day when we booted. Since then, some time may
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* have elapsed since the hypervisor wrote the data. So we try to account for
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* that with system time
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*/
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static void kvm_get_wallclock(struct timespec64 *now)
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{
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wrmsrl(msr_kvm_wall_clock, slow_virt_to_phys(&wall_clock));
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preempt_disable();
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pvclock_read_wallclock(&wall_clock, this_cpu_pvti(), now);
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preempt_enable();
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}
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static int kvm_set_wallclock(const struct timespec64 *now)
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{
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return -ENODEV;
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}
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static u64 kvm_clock_read(void)
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{
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u64 ret;
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preempt_disable_notrace();
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ret = pvclock_clocksource_read(this_cpu_pvti());
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preempt_enable_notrace();
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return ret;
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}
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static u64 kvm_clock_get_cycles(struct clocksource *cs)
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{
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return kvm_clock_read();
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}
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static u64 kvm_sched_clock_read(void)
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{
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return kvm_clock_read() - kvm_sched_clock_offset;
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}
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static inline void kvm_sched_clock_init(bool stable)
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{
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if (!stable)
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clear_sched_clock_stable();
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kvm_sched_clock_offset = kvm_clock_read();
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pv_ops.time.sched_clock = kvm_sched_clock_read;
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pr_info("kvm-clock: using sched offset of %llu cycles",
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kvm_sched_clock_offset);
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BUILD_BUG_ON(sizeof(kvm_sched_clock_offset) >
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sizeof(((struct pvclock_vcpu_time_info *)NULL)->system_time));
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}
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/*
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* If we don't do that, there is the possibility that the guest
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* will calibrate under heavy load - thus, getting a lower lpj -
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* and execute the delays themselves without load. This is wrong,
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* because no delay loop can finish beforehand.
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* Any heuristics is subject to fail, because ultimately, a large
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* poll of guests can be running and trouble each other. So we preset
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* lpj here
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*/
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static unsigned long kvm_get_tsc_khz(void)
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{
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setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ);
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return pvclock_tsc_khz(this_cpu_pvti());
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}
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static void __init kvm_get_preset_lpj(void)
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{
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unsigned long khz;
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u64 lpj;
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khz = kvm_get_tsc_khz();
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lpj = ((u64)khz * 1000);
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do_div(lpj, HZ);
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preset_lpj = lpj;
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}
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bool kvm_check_and_clear_guest_paused(void)
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{
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struct pvclock_vsyscall_time_info *src = this_cpu_hvclock();
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bool ret = false;
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if (!src)
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return ret;
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if ((src->pvti.flags & PVCLOCK_GUEST_STOPPED) != 0) {
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src->pvti.flags &= ~PVCLOCK_GUEST_STOPPED;
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pvclock_touch_watchdogs();
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ret = true;
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}
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return ret;
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}
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static int kvm_cs_enable(struct clocksource *cs)
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{
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vclocks_set_used(VDSO_CLOCKMODE_PVCLOCK);
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return 0;
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}
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struct clocksource kvm_clock = {
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.name = "kvm-clock",
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.read = kvm_clock_get_cycles,
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.rating = 400,
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.mask = CLOCKSOURCE_MASK(64),
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.flags = CLOCK_SOURCE_IS_CONTINUOUS,
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.enable = kvm_cs_enable,
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};
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EXPORT_SYMBOL_GPL(kvm_clock);
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static void kvm_register_clock(char *txt)
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{
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struct pvclock_vsyscall_time_info *src = this_cpu_hvclock();
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u64 pa;
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if (!src)
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return;
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pa = slow_virt_to_phys(&src->pvti) | 0x01ULL;
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wrmsrl(msr_kvm_system_time, pa);
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pr_info("kvm-clock: cpu %d, msr %llx, %s", smp_processor_id(), pa, txt);
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}
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static void kvm_save_sched_clock_state(void)
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{
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}
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static void kvm_restore_sched_clock_state(void)
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{
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kvm_register_clock("primary cpu clock, resume");
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}
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#ifdef CONFIG_X86_LOCAL_APIC
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static void kvm_setup_secondary_clock(void)
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{
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kvm_register_clock("secondary cpu clock");
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}
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#endif
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/*
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* After the clock is registered, the host will keep writing to the
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* registered memory location. If the guest happens to shutdown, this memory
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* won't be valid. In cases like kexec, in which you install a new kernel, this
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* means a random memory location will be kept being written. So before any
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* kind of shutdown from our side, we unregister the clock by writing anything
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* that does not have the 'enable' bit set in the msr
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*/
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#ifdef CONFIG_KEXEC_CORE
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static void kvm_crash_shutdown(struct pt_regs *regs)
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{
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native_write_msr(msr_kvm_system_time, 0, 0);
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kvm_disable_steal_time();
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native_machine_crash_shutdown(regs);
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}
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#endif
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static void kvm_shutdown(void)
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{
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native_write_msr(msr_kvm_system_time, 0, 0);
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kvm_disable_steal_time();
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native_machine_shutdown();
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}
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static void __init kvmclock_init_mem(void)
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{
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unsigned long ncpus;
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unsigned int order;
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struct page *p;
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int r;
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if (HVC_BOOT_ARRAY_SIZE >= num_possible_cpus())
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return;
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ncpus = num_possible_cpus() - HVC_BOOT_ARRAY_SIZE;
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order = get_order(ncpus * sizeof(*hvclock_mem));
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p = alloc_pages(GFP_KERNEL, order);
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if (!p) {
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pr_warn("%s: failed to alloc %d pages", __func__, (1U << order));
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return;
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}
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hvclock_mem = page_address(p);
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/*
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* hvclock is shared between the guest and the hypervisor, must
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* be mapped decrypted.
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*/
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if (sev_active()) {
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r = set_memory_decrypted((unsigned long) hvclock_mem,
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1UL << order);
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if (r) {
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__free_pages(p, order);
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hvclock_mem = NULL;
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pr_warn("kvmclock: set_memory_decrypted() failed. Disabling\n");
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return;
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}
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}
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memset(hvclock_mem, 0, PAGE_SIZE << order);
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}
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static int __init kvm_setup_vsyscall_timeinfo(void)
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{
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#ifdef CONFIG_X86_64
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u8 flags;
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if (!per_cpu(hv_clock_per_cpu, 0) || !kvmclock_vsyscall)
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return 0;
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flags = pvclock_read_flags(&hv_clock_boot[0].pvti);
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if (!(flags & PVCLOCK_TSC_STABLE_BIT))
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return 0;
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kvm_clock.vdso_clock_mode = VDSO_CLOCKMODE_PVCLOCK;
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#endif
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kvmclock_init_mem();
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return 0;
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}
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early_initcall(kvm_setup_vsyscall_timeinfo);
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static int kvmclock_setup_percpu(unsigned int cpu)
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{
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struct pvclock_vsyscall_time_info *p = per_cpu(hv_clock_per_cpu, cpu);
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/*
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* The per cpu area setup replicates CPU0 data to all cpu
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* pointers. So carefully check. CPU0 has been set up in init
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* already.
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*/
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if (!cpu || (p && p != per_cpu(hv_clock_per_cpu, 0)))
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return 0;
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/* Use the static page for the first CPUs, allocate otherwise */
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if (cpu < HVC_BOOT_ARRAY_SIZE)
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p = &hv_clock_boot[cpu];
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else if (hvclock_mem)
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p = hvclock_mem + cpu - HVC_BOOT_ARRAY_SIZE;
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else
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return -ENOMEM;
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per_cpu(hv_clock_per_cpu, cpu) = p;
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return p ? 0 : -ENOMEM;
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}
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void __init kvmclock_init(void)
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{
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u8 flags;
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if (!kvm_para_available() || !kvmclock)
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return;
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if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE2)) {
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msr_kvm_system_time = MSR_KVM_SYSTEM_TIME_NEW;
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msr_kvm_wall_clock = MSR_KVM_WALL_CLOCK_NEW;
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} else if (!kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE)) {
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return;
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}
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if (cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "kvmclock:setup_percpu",
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kvmclock_setup_percpu, NULL) < 0) {
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return;
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}
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pr_info("kvm-clock: Using msrs %x and %x",
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msr_kvm_system_time, msr_kvm_wall_clock);
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this_cpu_write(hv_clock_per_cpu, &hv_clock_boot[0]);
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kvm_register_clock("primary cpu clock");
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pvclock_set_pvti_cpu0_va(hv_clock_boot);
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if (kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE_STABLE_BIT))
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pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT);
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flags = pvclock_read_flags(&hv_clock_boot[0].pvti);
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kvm_sched_clock_init(flags & PVCLOCK_TSC_STABLE_BIT);
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x86_platform.calibrate_tsc = kvm_get_tsc_khz;
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x86_platform.calibrate_cpu = kvm_get_tsc_khz;
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x86_platform.get_wallclock = kvm_get_wallclock;
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x86_platform.set_wallclock = kvm_set_wallclock;
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#ifdef CONFIG_X86_LOCAL_APIC
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x86_cpuinit.early_percpu_clock_init = kvm_setup_secondary_clock;
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#endif
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x86_platform.save_sched_clock_state = kvm_save_sched_clock_state;
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x86_platform.restore_sched_clock_state = kvm_restore_sched_clock_state;
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machine_ops.shutdown = kvm_shutdown;
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#ifdef CONFIG_KEXEC_CORE
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machine_ops.crash_shutdown = kvm_crash_shutdown;
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#endif
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kvm_get_preset_lpj();
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/*
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* X86_FEATURE_NONSTOP_TSC is TSC runs at constant rate
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* with P/T states and does not stop in deep C-states.
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*
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* Invariant TSC exposed by host means kvmclock is not necessary:
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* can use TSC as clocksource.
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*
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*/
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if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC) &&
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boot_cpu_has(X86_FEATURE_NONSTOP_TSC) &&
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!check_tsc_unstable())
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kvm_clock.rating = 299;
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clocksource_register_hz(&kvm_clock, NSEC_PER_SEC);
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pv_info.name = "KVM";
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}
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