v4.19.13 snapshot.
diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
new file mode 100644
index 0000000..013fe3d
--- /dev/null
+++ b/arch/x86/kernel/kvmclock.c
@@ -0,0 +1,373 @@
+/* KVM paravirtual clock driver. A clocksource implementation
+ Copyright (C) 2008 Glauber de Oliveira Costa, Red Hat Inc.
+
+ This program is free software; you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 2 of the License, or
+ (at your option) any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU General Public License for more details.
+
+ You should have received a copy of the GNU General Public License
+ along with this program; if not, write to the Free Software
+ Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
+*/
+
+#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/reboot.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) {
+ pv_time_ops.sched_clock = kvm_clock_read;
+ clear_sched_clock_stable();
+ return;
+ }
+
+ kvm_sched_clock_offset = kvm_clock_read();
+ pv_time_ops.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
+
+/*
+ * After the clock is registered, the host will keep writing to the
+ * registered memory location. If the guest happens to shutdown, this memory
+ * won't be valid. In cases like kexec, in which you install a new kernel, this
+ * means a random memory location will be kept being written. So before any
+ * kind of shutdown from our side, we unregister the clock by writing anything
+ * that does not have the 'enable' bit set in the msr
+ */
+#ifdef CONFIG_KEXEC_CORE
+static void kvm_crash_shutdown(struct pt_regs *regs)
+{
+ native_write_msr(msr_kvm_system_time, 0, 0);
+ kvm_disable_steal_time();
+ native_machine_crash_shutdown(regs);
+}
+#endif
+
+static void kvm_shutdown(void)
+{
+ native_write_msr(msr_kvm_system_time, 0, 0);
+ kvm_disable_steal_time();
+ native_machine_shutdown();
+}
+
+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;
+ machine_ops.shutdown = kvm_shutdown;
+#ifdef CONFIG_KEXEC_CORE
+ machine_ops.crash_shutdown = kvm_crash_shutdown;
+#endif
+ kvm_get_preset_lpj();
+ clocksource_register_hz(&kvm_clock, NSEC_PER_SEC);
+ pv_info.name = "KVM";
+}