From 536395260582be7443b0b35b0bbb89ffe3947f62 Mon Sep 17 00:00:00 2001 From: Joao Martins Date: Thu, 3 Mar 2022 15:41:22 +0000 Subject: [PATCH] KVM: x86/xen: handle PV timers oneshot mode If the guest has offloaded the timer virq, handle the following hypercalls for programming the timer: VCPUOP_set_singleshot_timer VCPUOP_stop_singleshot_timer set_timer_op(timestamp_ns) The event channel corresponding to the timer virq is then used to inject events once timer deadlines are met. For now we back the PV timer with hrtimer. [ dwmw2: Add save/restore, 32-bit compat mode, immediate delivery, don't check timer in kvm_vcpu_has_event() ] Signed-off-by: Joao Martins Signed-off-by: David Woodhouse Signed-off-by: Paolo Bonzini Message-Id: <20220303154127.202856-13-dwmw2@infradead.org> Signed-off-by: Paolo Bonzini --- arch/x86/include/asm/kvm_host.h | 4 + arch/x86/kvm/irq.c | 10 +- arch/x86/kvm/xen.c | 211 ++++++++++++++++++++++++++++++++ arch/x86/kvm/xen.h | 28 +++++ include/uapi/linux/kvm.h | 6 + 5 files changed, 257 insertions(+), 2 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 9e3408542b41..8193d5285544 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -614,6 +614,10 @@ struct kvm_vcpu_xen { u64 runstate_times[4]; unsigned long evtchn_pending_sel; u32 vcpu_id; /* The Xen / ACPI vCPU ID */ + u32 timer_virq; + u64 timer_expires; /* In guest epoch */ + atomic_t timer_pending; + struct hrtimer timer; }; struct kvm_vcpu_arch { diff --git a/arch/x86/kvm/irq.c b/arch/x86/kvm/irq.c index 172b05343cfd..f371f1292ca3 100644 --- a/arch/x86/kvm/irq.c +++ b/arch/x86/kvm/irq.c @@ -22,10 +22,14 @@ */ int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu) { + int r = 0; + if (lapic_in_kernel(vcpu)) - return apic_has_pending_timer(vcpu); + r = apic_has_pending_timer(vcpu); + if (kvm_xen_timer_enabled(vcpu)) + r += kvm_xen_has_pending_timer(vcpu); - return 0; + return r; } EXPORT_SYMBOL(kvm_cpu_has_pending_timer); @@ -143,6 +147,8 @@ void kvm_inject_pending_timer_irqs(struct kvm_vcpu *vcpu) { if (lapic_in_kernel(vcpu)) kvm_inject_apic_timer_irqs(vcpu); + if (kvm_xen_timer_enabled(vcpu)) + kvm_xen_inject_timer_irqs(vcpu); } EXPORT_SYMBOL_GPL(kvm_inject_pending_timer_irqs); diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c index 244cf3cd858a..0e1595dc8c5f 100644 --- a/arch/x86/kvm/xen.c +++ b/arch/x86/kvm/xen.c @@ -23,6 +23,7 @@ #include "trace.h" +static int kvm_xen_set_evtchn(struct kvm_xen_evtchn *xe, struct kvm *kvm); static int kvm_xen_setattr_evtchn(struct kvm *kvm, struct kvm_xen_hvm_attr *data); static bool kvm_xen_hcall_evtchn_send(struct kvm_vcpu *vcpu, u64 param, u64 *r); @@ -108,6 +109,66 @@ out: return ret; } +void kvm_xen_inject_timer_irqs(struct kvm_vcpu *vcpu) +{ + if (atomic_read(&vcpu->arch.xen.timer_pending) > 0) { + struct kvm_xen_evtchn e; + + e.vcpu_id = vcpu->vcpu_id; + e.vcpu_idx = vcpu->vcpu_idx; + e.port = vcpu->arch.xen.timer_virq; + e.priority = KVM_IRQ_ROUTING_XEN_EVTCHN_PRIO_2LEVEL; + + kvm_xen_set_evtchn(&e, vcpu->kvm); + + vcpu->arch.xen.timer_expires = 0; + atomic_set(&vcpu->arch.xen.timer_pending, 0); + } +} + +static enum hrtimer_restart xen_timer_callback(struct hrtimer *timer) +{ + struct kvm_vcpu *vcpu = container_of(timer, struct kvm_vcpu, + arch.xen.timer); + if (atomic_read(&vcpu->arch.xen.timer_pending)) + return HRTIMER_NORESTART; + + atomic_inc(&vcpu->arch.xen.timer_pending); + kvm_make_request(KVM_REQ_UNBLOCK, vcpu); + kvm_vcpu_kick(vcpu); + + return HRTIMER_NORESTART; +} + +static void kvm_xen_start_timer(struct kvm_vcpu *vcpu, u64 guest_abs, s64 delta_ns) +{ + atomic_set(&vcpu->arch.xen.timer_pending, 0); + vcpu->arch.xen.timer_expires = guest_abs; + + if (delta_ns <= 0) { + xen_timer_callback(&vcpu->arch.xen.timer); + } else { + ktime_t ktime_now = ktime_get(); + hrtimer_start(&vcpu->arch.xen.timer, + ktime_add_ns(ktime_now, delta_ns), + HRTIMER_MODE_ABS_HARD); + } +} + +static void kvm_xen_stop_timer(struct kvm_vcpu *vcpu) +{ + hrtimer_cancel(&vcpu->arch.xen.timer); + vcpu->arch.xen.timer_expires = 0; + atomic_set(&vcpu->arch.xen.timer_pending, 0); +} + +static void kvm_xen_init_timer(struct kvm_vcpu *vcpu) +{ + hrtimer_init(&vcpu->arch.xen.timer, CLOCK_MONOTONIC, + HRTIMER_MODE_ABS_HARD); + vcpu->arch.xen.timer.function = xen_timer_callback; +} + static void kvm_xen_update_runstate(struct kvm_vcpu *v, int state) { struct kvm_vcpu_xen *vx = &v->arch.xen; @@ -612,6 +673,28 @@ int kvm_xen_vcpu_set_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data) } break; + case KVM_XEN_VCPU_ATTR_TYPE_TIMER: + if (data->u.timer.port) { + if (data->u.timer.priority != KVM_IRQ_ROUTING_XEN_EVTCHN_PRIO_2LEVEL) { + r = -EINVAL; + break; + } + vcpu->arch.xen.timer_virq = data->u.timer.port; + kvm_xen_init_timer(vcpu); + + /* Restart the timer if it's set */ + if (data->u.timer.expires_ns) + kvm_xen_start_timer(vcpu, data->u.timer.expires_ns, + data->u.timer.expires_ns - + get_kvmclock_ns(vcpu->kvm)); + } else if (kvm_xen_timer_enabled(vcpu)) { + kvm_xen_stop_timer(vcpu); + vcpu->arch.xen.timer_virq = 0; + } + + r = 0; + break; + default: break; } @@ -692,6 +775,13 @@ int kvm_xen_vcpu_get_attr(struct kvm_vcpu *vcpu, struct kvm_xen_vcpu_attr *data) r = 0; break; + case KVM_XEN_VCPU_ATTR_TYPE_TIMER: + data->u.timer.port = vcpu->arch.xen.timer_virq; + data->u.timer.priority = KVM_IRQ_ROUTING_XEN_EVTCHN_PRIO_2LEVEL; + data->u.timer.expires_ns = vcpu->arch.xen.timer_expires; + r = 0; + break; + default: break; } @@ -827,6 +917,112 @@ static bool kvm_xen_hcall_sched_op(struct kvm_vcpu *vcpu, int cmd, u64 param, u6 return false; } +struct compat_vcpu_set_singleshot_timer { + uint64_t timeout_abs_ns; + uint32_t flags; +} __attribute__((packed)); + +static bool kvm_xen_hcall_vcpu_op(struct kvm_vcpu *vcpu, bool longmode, int cmd, + int vcpu_id, u64 param, u64 *r) +{ + struct vcpu_set_singleshot_timer oneshot; + s64 delta; + gpa_t gpa; + int idx; + + if (!kvm_xen_timer_enabled(vcpu)) + return false; + + switch (cmd) { + case VCPUOP_set_singleshot_timer: + if (vcpu->arch.xen.vcpu_id != vcpu_id) { + *r = -EINVAL; + return true; + } + idx = srcu_read_lock(&vcpu->kvm->srcu); + gpa = kvm_mmu_gva_to_gpa_system(vcpu, param, NULL); + srcu_read_unlock(&vcpu->kvm->srcu, idx); + + /* + * The only difference for 32-bit compat is the 4 bytes of + * padding after the interesting part of the structure. So + * for a faithful emulation of Xen we have to *try* to copy + * the padding and return -EFAULT if we can't. Otherwise we + * might as well just have copied the 12-byte 32-bit struct. + */ + BUILD_BUG_ON(offsetof(struct compat_vcpu_set_singleshot_timer, timeout_abs_ns) != + offsetof(struct vcpu_set_singleshot_timer, timeout_abs_ns)); + BUILD_BUG_ON(sizeof_field(struct compat_vcpu_set_singleshot_timer, timeout_abs_ns) != + sizeof_field(struct vcpu_set_singleshot_timer, timeout_abs_ns)); + BUILD_BUG_ON(offsetof(struct compat_vcpu_set_singleshot_timer, flags) != + offsetof(struct vcpu_set_singleshot_timer, flags)); + BUILD_BUG_ON(sizeof_field(struct compat_vcpu_set_singleshot_timer, flags) != + sizeof_field(struct vcpu_set_singleshot_timer, flags)); + + if (!gpa || + kvm_vcpu_read_guest(vcpu, gpa, &oneshot, longmode ? sizeof(oneshot) : + sizeof(struct compat_vcpu_set_singleshot_timer))) { + *r = -EFAULT; + return true; + } + + delta = oneshot.timeout_abs_ns - get_kvmclock_ns(vcpu->kvm); + if ((oneshot.flags & VCPU_SSHOTTMR_future) && delta < 0) { + *r = -ETIME; + return true; + } + + kvm_xen_start_timer(vcpu, oneshot.timeout_abs_ns, delta); + *r = 0; + return true; + + case VCPUOP_stop_singleshot_timer: + if (vcpu->arch.xen.vcpu_id != vcpu_id) { + *r = -EINVAL; + return true; + } + kvm_xen_stop_timer(vcpu); + *r = 0; + return true; + } + + return false; +} + +static bool kvm_xen_hcall_set_timer_op(struct kvm_vcpu *vcpu, uint64_t timeout, + u64 *r) +{ + if (!kvm_xen_timer_enabled(vcpu)) + return false; + + if (timeout) { + uint64_t guest_now = get_kvmclock_ns(vcpu->kvm); + int64_t delta = timeout - guest_now; + + /* Xen has a 'Linux workaround' in do_set_timer_op() which + * checks for negative absolute timeout values (caused by + * integer overflow), and for values about 13 days in the + * future (2^50ns) which would be caused by jiffies + * overflow. For those cases, it sets the timeout 100ms in + * the future (not *too* soon, since if a guest really did + * set a long timeout on purpose we don't want to keep + * churning CPU time by waking it up). + */ + if (unlikely((int64_t)timeout < 0 || + (delta > 0 && (uint32_t) (delta >> 50) != 0))) { + delta = 100 * NSEC_PER_MSEC; + timeout = guest_now + delta; + } + + kvm_xen_start_timer(vcpu, timeout, delta); + } else { + kvm_xen_stop_timer(vcpu); + } + + *r = 0; + return true; +} + int kvm_xen_hypercall(struct kvm_vcpu *vcpu) { bool longmode; @@ -870,6 +1066,18 @@ int kvm_xen_hypercall(struct kvm_vcpu *vcpu) case __HYPERVISOR_sched_op: handled = kvm_xen_hcall_sched_op(vcpu, params[0], params[1], &r); break; + case __HYPERVISOR_vcpu_op: + handled = kvm_xen_hcall_vcpu_op(vcpu, longmode, params[0], params[1], + params[2], &r); + break; + case __HYPERVISOR_set_timer_op: { + u64 timeout = params[0]; + /* In 32-bit mode, the 64-bit timeout is in two 32-bit params. */ + if (!longmode) + timeout |= params[1] << 32; + handled = kvm_xen_hcall_set_timer_op(vcpu, timeout, &r); + break; + } default: break; } @@ -1398,6 +1606,9 @@ void kvm_xen_init_vcpu(struct kvm_vcpu *vcpu) void kvm_xen_destroy_vcpu(struct kvm_vcpu *vcpu) { + if (kvm_xen_timer_enabled(vcpu)) + kvm_xen_stop_timer(vcpu); + kvm_gfn_to_pfn_cache_destroy(vcpu->kvm, &vcpu->arch.xen.runstate_cache); kvm_gfn_to_pfn_cache_destroy(vcpu->kvm, diff --git a/arch/x86/kvm/xen.h b/arch/x86/kvm/xen.h index 54d587aae85b..ee5c4ae0755c 100644 --- a/arch/x86/kvm/xen.h +++ b/arch/x86/kvm/xen.h @@ -62,6 +62,20 @@ static inline bool kvm_xen_has_pending_events(struct kvm_vcpu *vcpu) vcpu->arch.xen.evtchn_pending_sel; } +static inline bool kvm_xen_timer_enabled(struct kvm_vcpu *vcpu) +{ + return !!vcpu->arch.xen.timer_virq; +} + +static inline int kvm_xen_has_pending_timer(struct kvm_vcpu *vcpu) +{ + if (kvm_xen_hypercall_enabled(vcpu->kvm) && kvm_xen_timer_enabled(vcpu)) + return atomic_read(&vcpu->arch.xen.timer_pending); + + return 0; +} + +void kvm_xen_inject_timer_irqs(struct kvm_vcpu *vcpu); #else static inline int kvm_xen_write_hypercall_page(struct kvm_vcpu *vcpu, u64 data) { @@ -107,6 +121,20 @@ static inline bool kvm_xen_has_pending_events(struct kvm_vcpu *vcpu) { return false; } + +static inline int kvm_xen_has_pending_timer(struct kvm_vcpu *vcpu) +{ + return 0; +} + +static inline void kvm_xen_inject_timer_irqs(struct kvm_vcpu *vcpu) +{ +} + +static inline bool kvm_xen_timer_enabled(struct kvm_vcpu *vcpu) +{ + return false; +} #endif int kvm_xen_hypercall(struct kvm_vcpu *vcpu); diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index 4b65e9f0a4d9..cb223e425223 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -1748,6 +1748,11 @@ struct kvm_xen_vcpu_attr { __u64 time_offline; } runstate; __u32 vcpu_id; + struct { + __u32 port; + __u32 priority; + __u64 expires_ns; + } timer; } u; }; @@ -1760,6 +1765,7 @@ struct kvm_xen_vcpu_attr { #define KVM_XEN_VCPU_ATTR_TYPE_RUNSTATE_ADJUST 0x5 /* Available with KVM_CAP_XEN_HVM / KVM_XEN_HVM_CONFIG_EVTCHN_SEND */ #define KVM_XEN_VCPU_ATTR_TYPE_VCPU_ID 0x6 +#define KVM_XEN_VCPU_ATTR_TYPE_TIMER 0x7 /* Secure Encrypted Virtualization command */ enum sev_cmd_id { -- 2.20.1