Add guest side implementation of KVM virtual suspend time injection. How it works from guest's view: - Guest will be paused without going through suspend/resume path in the guest kernel - Before resuming the execution of the guest's vcpus, host will adjust the hardware clock (and kvm_clock) to the time before the suspend. - By this action, guest's CLOCK_MONOTONIC behaves as expected (stops during the host's suspension.) - the guest will receive an IRQ from the guest that notifies about the suspend which was invisible to the guest. In the handler, the guest can adjust their CLOCK_BOOTTIME to reflect the suspension. - Now, CLOCK_BOOTTIME includes the time passed during the host's suspension. Signed-off-by: Hikaru Nishida <hikalium@xxxxxxxxxxxx> --- Changes in v3: - Reused HYPERVISOR_CALLBACK_VECTOR IRQ instead of adding a new one. - Extracted arch-independent parts. arch/x86/Kconfig | 13 ++++++++ arch/x86/include/asm/idtentry.h | 2 +- arch/x86/include/asm/kvmclock.h | 9 ++++++ arch/x86/kernel/kvm.c | 14 ++++++--- arch/x86/kernel/kvmclock.c | 26 ++++++++++++++++ arch/x86/mm/fault.c | 2 +- include/linux/timekeeper_internal.h | 5 ++++ include/linux/timekeeping.h | 4 +++ kernel/time/timekeeping.c | 46 +++++++++++++++++++++++++++++ 9 files changed, 115 insertions(+), 6 deletions(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index d9830e7e1060..1d4a529d1577 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -824,6 +824,19 @@ config KVM_GUEST underlying device model, the host provides the guest with timing infrastructure such as time of day, and system time +config KVM_VIRT_SUSPEND_TIMING_GUEST + bool "Guest support for virtual suspend time injection" + depends on KVM_GUEST + default n + help + This option makes the host's suspension reflected on the guest's clocks. + In other words, guest's CLOCK_MONOTONIC will stop and + CLOCK_BOOTTIME keeps running during the host's suspension. + This feature will only be effective when both guest and host support + this feature. For the host side, see KVM_VIRT_SUSPEND_TIMING. + + If unsure, say N. + config ARCH_CPUIDLE_HALTPOLL def_bool n prompt "Disable host haltpoll when loading haltpoll driver" diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h index 1345088e9902..5e30f84ea07e 100644 --- a/arch/x86/include/asm/idtentry.h +++ b/arch/x86/include/asm/idtentry.h @@ -686,7 +686,7 @@ DECLARE_IDTENTRY_SYSVEC(HYPERVISOR_CALLBACK_VECTOR, sysvec_xen_hvm_callback); #endif #ifdef CONFIG_KVM_GUEST -DECLARE_IDTENTRY_SYSVEC(HYPERVISOR_CALLBACK_VECTOR, sysvec_kvm_asyncpf_interrupt); +DECLARE_IDTENTRY_SYSVEC(HYPERVISOR_CALLBACK_VECTOR, sysvec_kvm_hv_callback); #endif #undef X86_TRAP_OTHER diff --git a/arch/x86/include/asm/kvmclock.h b/arch/x86/include/asm/kvmclock.h index 9add14edc24d..2bf1a5c92319 100644 --- a/arch/x86/include/asm/kvmclock.h +++ b/arch/x86/include/asm/kvmclock.h @@ -20,4 +20,13 @@ static inline struct pvclock_vsyscall_time_info *this_cpu_hvclock(void) return this_cpu_read(hv_clock_per_cpu); } +#ifdef CONFIG_KVM_VIRT_SUSPEND_TIMING_GUEST +u64 kvm_get_suspend_time(void); +#else +static inline u64 kvm_get_suspend_time(void) +{ + return 0; +} +#endif + #endif /* _ASM_X86_KVM_CLOCK_H */ diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index b656456c3a94..3d84ef6d9df2 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -40,6 +40,7 @@ #include <asm/ptrace.h> #include <asm/reboot.h> #include <asm/svm.h> +#include <asm/kvmclock.h> DEFINE_STATIC_KEY_FALSE(kvm_async_pf_enabled); @@ -270,7 +271,7 @@ noinstr bool __kvm_handle_async_pf(struct pt_regs *regs, u32 token) return true; } -DEFINE_IDTENTRY_SYSVEC(sysvec_kvm_asyncpf_interrupt) +DEFINE_IDTENTRY_SYSVEC(sysvec_kvm_hv_callback) { struct pt_regs *old_regs = set_irq_regs(regs); u32 token; @@ -286,6 +287,8 @@ DEFINE_IDTENTRY_SYSVEC(sysvec_kvm_asyncpf_interrupt) wrmsrl(MSR_KVM_ASYNC_PF_ACK, 1); } + timekeeping_inject_virtual_suspend_time(kvm_get_suspend_time()); + set_irq_regs(old_regs); } @@ -710,10 +713,13 @@ static void __init kvm_guest_init(void) if (kvm_para_has_feature(KVM_FEATURE_PV_EOI)) apic_set_eoi_write(kvm_guest_apic_eoi_write); - if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) { + if (kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) static_branch_enable(&kvm_async_pf_enabled); - alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, asm_sysvec_kvm_asyncpf_interrupt); - } + + if ((kvm_para_has_feature(KVM_FEATURE_ASYNC_PF_INT) && kvmapf) || + kvm_para_has_feature(KVM_FEATURE_HOST_SUSPEND_TIME)) + alloc_intr_gate(HYPERVISOR_CALLBACK_VECTOR, + asm_sysvec_kvm_hv_callback); #ifdef CONFIG_SMP if (pv_tlb_flush_supported()) { diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c index 73c74b961d0f..3e16d0ab79f3 100644 --- a/arch/x86/kernel/kvmclock.c +++ b/arch/x86/kernel/kvmclock.c @@ -16,11 +16,15 @@ #include <linux/mm.h> #include <linux/slab.h> #include <linux/set_memory.h> +#include <linux/interrupt.h> +#include <linux/irq.h> #include <asm/hypervisor.h> #include <asm/mem_encrypt.h> #include <asm/x86_init.h> #include <asm/kvmclock.h> +#include <asm/desc.h> +#include <asm/idtentry.h> static int kvmclock __initdata = 1; static int kvmclock_vsyscall __initdata = 1; @@ -48,6 +52,9 @@ early_param("no-kvmclock-vsyscall", parse_no_kvmclock_vsyscall); static struct pvclock_vsyscall_time_info hv_clock_boot[HVC_BOOT_ARRAY_SIZE] __bss_decrypted __aligned(PAGE_SIZE); +#ifdef CONFIG_KVM_VIRT_SUSPEND_TIMING_GUEST +static struct kvm_suspend_time suspend_time __bss_decrypted; +#endif static struct pvclock_wall_clock wall_clock __bss_decrypted; static struct pvclock_vsyscall_time_info *hvclock_mem; DEFINE_PER_CPU(struct pvclock_vsyscall_time_info *, hv_clock_per_cpu); @@ -281,6 +288,17 @@ static int kvmclock_setup_percpu(unsigned int cpu) return p ? 0 : -ENOMEM; } +#ifdef CONFIG_KVM_VIRT_SUSPEND_TIMING_GUEST +/** + * kvm_get_suspend_time - duration of host suspend. + * Return: Cumulative duration of host suspend in nanoseconds. + */ +u64 kvm_get_suspend_time(void) +{ + return suspend_time.suspend_time_ns; +} +#endif + void __init kvmclock_init(void) { u8 flags; @@ -295,6 +313,14 @@ void __init kvmclock_init(void) return; } +#ifdef CONFIG_KVM_VIRT_SUSPEND_TIMING_GUEST + if (kvm_para_has_feature(KVM_FEATURE_HOST_SUSPEND_TIME)) { + /* Register the suspend time structure */ + wrmsrl(MSR_KVM_HOST_SUSPEND_TIME, + slow_virt_to_phys(&suspend_time) | KVM_MSR_ENABLED); + } +#endif + if (cpuhp_setup_state(CPUHP_BP_PREPARE_DYN, "kvmclock:setup_percpu", kvmclock_setup_percpu, NULL) < 0) { return; diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 84a2c8c4af73..f36f49585d5d 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -1509,7 +1509,7 @@ DEFINE_IDTENTRY_RAW_ERRORCODE(exc_page_fault) * memory is swapped out). Note, the corresponding "page ready" event * which is injected when the memory becomes available, is delivered via * an interrupt mechanism and not a #PF exception - * (see arch/x86/kernel/kvm.c: sysvec_kvm_asyncpf_interrupt()). + * (see arch/x86/kernel/kvm.c: sysvec_kvm_hv_callback()). * * We are relying on the interrupted context being sane (valid RSP, * relevant locks not held, etc.), which is fine as long as the diff --git a/include/linux/timekeeper_internal.h b/include/linux/timekeeper_internal.h index 84ff2844df2a..0d5b29122d40 100644 --- a/include/linux/timekeeper_internal.h +++ b/include/linux/timekeeper_internal.h @@ -68,6 +68,8 @@ struct tk_read_base { * shifted nano seconds. * @ntp_error_shift: Shift conversion between clock shifted nano seconds and * ntp shifted nano seconds. + * @kvm_suspend_time: The cumulative duration of suspend injected through KVM + * in nano seconds. * @last_warning: Warning ratelimiter (DEBUG_TIMEKEEPING) * @underflow_seen: Underflow warning flag (DEBUG_TIMEKEEPING) * @overflow_seen: Overflow warning flag (DEBUG_TIMEKEEPING) @@ -124,6 +126,9 @@ struct timekeeper { u32 ntp_err_mult; /* Flag used to avoid updating NTP twice with same second */ u32 skip_second_overflow; +#ifdef CONFIG_KVM_VIRT_SUSPEND_TIMING_GUEST + u64 kvm_suspend_time; +#endif #ifdef CONFIG_DEBUG_TIMEKEEPING long last_warning; /* diff --git a/include/linux/timekeeping.h b/include/linux/timekeeping.h index f7be69c81dab..a2228300c3f9 100644 --- a/include/linux/timekeeping.h +++ b/include/linux/timekeeping.h @@ -310,4 +310,8 @@ void read_persistent_wall_and_boot_offset(struct timespec64 *wall_clock, extern int update_persistent_clock64(struct timespec64 now); #endif +#ifdef CONFIG_KVM_VIRT_SUSPEND_TIMING_GUEST +void timekeeping_inject_virtual_suspend_time(u64 total_duration_ns); +#endif + #endif diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index e77580d9f8c1..5f474cde0bae 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -2133,6 +2133,52 @@ static u64 logarithmic_accumulation(struct timekeeper *tk, u64 offset, return offset; } +#ifdef CONFIG_KVM_VIRT_SUSPEND_TIMING_GUEST +/** + * timekeeping_inject_virtual_suspend_time - Inject virtual suspend time + * when requested by the kvm host. + * @total_duration_ns: Total suspend time to be injected in nanoseconds. + */ +void timekeeping_inject_virtual_suspend_time(u64 total_duration_ns) +{ + struct timekeeper *tk = &tk_core.timekeeper; + unsigned long flags; + + raw_spin_lock_irqsave(&timekeeper_lock, flags); + if (total_duration_ns > tk->kvm_suspend_time) { + /* + * Do injection only if the time is not injected yet. + * total_duration_ns and tk->kvm_suspend_time values are + * cumulative, so the delta between them will be an amount + * of adjustments. For example, if the host suspends 2 times + * during the guest is running and each suspend is 5 seconds, + * total_duration_ns will be 5 seconds at the first injection + * and tk->kvm_suspend_time was initialized to zero so the + * adjustment injected here will be 5 - 0 = 5 seconds and + * tk->kvm_suspend_time will be updated to 5 seconds. + * On the second injection after the second resume, + * total_duration_ns will be 10 seconds and + * tk->kvm_suspend_time will be 5 seconds so 10 - 5 = 5 seconds + * of the suspend time will be injected again. + */ + struct timespec64 delta = + ns_to_timespec64(total_duration_ns - + tk->kvm_suspend_time); + tk->kvm_suspend_time = total_duration_ns; + + write_seqcount_begin(&tk_core.seq); + timekeeping_forward_now(tk); + __timekeeping_inject_sleeptime(tk, &delta); + timekeeping_update(tk, TK_CLEAR_NTP | TK_MIRROR | TK_CLOCK_WAS_SET); + write_seqcount_end(&tk_core.seq); + + /* signal hrtimers about time change */ + clock_was_set_delayed(); + } + raw_spin_unlock_irqrestore(&timekeeper_lock, flags); +} +#endif + /* * timekeeping_advance - Updates the timekeeper to the current time and * current NTP tick length -- 2.33.0.1079.g6e70778dc9-goog _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm