From 66450a21f99636af4fafac2afd33f1a40631bc3a Mon Sep 17 00:00:00 2001 From: Jan Kiszka Date: Wed, 13 Mar 2013 12:42:34 +0100 Subject: [PATCH] KVM: x86: Rework INIT and SIPI handling A VCPU sending INIT or SIPI to some other VCPU races for setting the remote VCPU's mp_state. When we were unlucky, KVM_MP_STATE_INIT_RECEIVED was overwritten by kvm_emulate_halt and, thus, got lost. This introduces APIC events for those two signals, keeping them in kvm_apic until kvm_apic_accept_events is run over the target vcpu context. kvm_apic_has_events reports to kvm_arch_vcpu_runnable if there are pending events, thus if vcpu blocking should end. The patch comes with the side effect of effectively obsoleting KVM_MP_STATE_SIPI_RECEIVED. We still accept it from user space, but immediately translate it to KVM_MP_STATE_INIT_RECEIVED + KVM_APIC_SIPI. The vcpu itself will no longer enter the KVM_MP_STATE_SIPI_RECEIVED state. That also means we no longer exit to user space after receiving a SIPI event. Furthermore, we already reset the VCPU on INIT, only fixing up the code segment later on when SIPI arrives. Moreover, we fix INIT handling for the BSP: it never enter wait-for-SIPI but directly starts over on INIT. Tested-by: Paolo Bonzini Signed-off-by: Jan Kiszka Signed-off-by: Gleb Natapov --- arch/x86/include/asm/kvm_host.h | 3 +- arch/x86/kvm/lapic.c | 48 ++++++++++++++++++++++----- arch/x86/kvm/lapic.h | 11 +++++++ arch/x86/kvm/svm.c | 6 ---- arch/x86/kvm/vmx.c | 12 ++----- arch/x86/kvm/x86.c | 58 +++++++++++++++++++++------------ 6 files changed, 93 insertions(+), 45 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 348d85965ead..ef7f4a5cf8c7 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -345,7 +345,6 @@ struct kvm_vcpu_arch { unsigned long apic_attention; int32_t apic_arb_prio; int mp_state; - int sipi_vector; u64 ia32_misc_enable_msr; bool tpr_access_reporting; @@ -819,6 +818,7 @@ int kvm_emulate_wbinvd(struct kvm_vcpu *vcpu); void kvm_get_segment(struct kvm_vcpu *vcpu, struct kvm_segment *var, int seg); int kvm_load_segment_descriptor(struct kvm_vcpu *vcpu, u16 selector, int seg); +void kvm_vcpu_deliver_sipi_vector(struct kvm_vcpu *vcpu, unsigned int vector); int kvm_task_switch(struct kvm_vcpu *vcpu, u16 tss_selector, int idt_index, int reason, bool has_error_code, u32 error_code); @@ -1002,6 +1002,7 @@ int kvm_cpu_has_injectable_intr(struct kvm_vcpu *v); int kvm_cpu_has_interrupt(struct kvm_vcpu *vcpu); int kvm_arch_interrupt_allowed(struct kvm_vcpu *vcpu); int kvm_cpu_get_interrupt(struct kvm_vcpu *v); +void kvm_vcpu_reset(struct kvm_vcpu *vcpu); void kvm_define_shared_msr(unsigned index, u32 msr); void kvm_set_shared_msr(unsigned index, u64 val, u64 mask); diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 02b51dd4e4ad..a8e9369f41c5 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -731,7 +731,11 @@ static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode, case APIC_DM_INIT: if (!trig_mode || level) { result = 1; - vcpu->arch.mp_state = KVM_MP_STATE_INIT_RECEIVED; + /* assumes that there are only KVM_APIC_INIT/SIPI */ + apic->pending_events = (1UL << KVM_APIC_INIT); + /* make sure pending_events is visible before sending + * the request */ + smp_wmb(); kvm_make_request(KVM_REQ_EVENT, vcpu); kvm_vcpu_kick(vcpu); } else { @@ -743,13 +747,13 @@ static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode, case APIC_DM_STARTUP: apic_debug("SIPI to vcpu %d vector 0x%02x\n", vcpu->vcpu_id, vector); - if (vcpu->arch.mp_state == KVM_MP_STATE_INIT_RECEIVED) { - result = 1; - vcpu->arch.sipi_vector = vector; - vcpu->arch.mp_state = KVM_MP_STATE_SIPI_RECEIVED; - kvm_make_request(KVM_REQ_EVENT, vcpu); - kvm_vcpu_kick(vcpu); - } + result = 1; + apic->sipi_vector = vector; + /* make sure sipi_vector is visible for the receiver */ + smp_wmb(); + set_bit(KVM_APIC_SIPI, &apic->pending_events); + kvm_make_request(KVM_REQ_EVENT, vcpu); + kvm_vcpu_kick(vcpu); break; case APIC_DM_EXTINT: @@ -1860,6 +1864,34 @@ int kvm_lapic_enable_pv_eoi(struct kvm_vcpu *vcpu, u64 data) addr); } +void kvm_apic_accept_events(struct kvm_vcpu *vcpu) +{ + struct kvm_lapic *apic = vcpu->arch.apic; + unsigned int sipi_vector; + + if (!kvm_vcpu_has_lapic(vcpu)) + return; + + if (test_and_clear_bit(KVM_APIC_INIT, &apic->pending_events)) { + kvm_lapic_reset(vcpu); + kvm_vcpu_reset(vcpu); + if (kvm_vcpu_is_bsp(apic->vcpu)) + vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE; + else + vcpu->arch.mp_state = KVM_MP_STATE_INIT_RECEIVED; + } + if (test_and_clear_bit(KVM_APIC_SIPI, &apic->pending_events) && + vcpu->arch.mp_state == KVM_MP_STATE_INIT_RECEIVED) { + /* evaluate pending_events before reading the vector */ + smp_rmb(); + sipi_vector = apic->sipi_vector; + pr_debug("vcpu %d received sipi with vector # %x\n", + vcpu->vcpu_id, sipi_vector); + kvm_vcpu_deliver_sipi_vector(vcpu, sipi_vector); + vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE; + } +} + void kvm_lapic_init(void) { /* do not patch jump label more than once per second */ diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h index 1676d34ddb4e..2c721b986eec 100644 --- a/arch/x86/kvm/lapic.h +++ b/arch/x86/kvm/lapic.h @@ -5,6 +5,9 @@ #include +#define KVM_APIC_INIT 0 +#define KVM_APIC_SIPI 1 + struct kvm_timer { struct hrtimer timer; s64 period; /* unit: ns */ @@ -32,6 +35,8 @@ struct kvm_lapic { void *regs; gpa_t vapic_addr; struct page *vapic_page; + unsigned long pending_events; + unsigned int sipi_vector; }; int kvm_create_lapic(struct kvm_vcpu *vcpu); void kvm_free_lapic(struct kvm_vcpu *vcpu); @@ -39,6 +44,7 @@ void kvm_free_lapic(struct kvm_vcpu *vcpu); int kvm_apic_has_interrupt(struct kvm_vcpu *vcpu); int kvm_apic_accept_pic_intr(struct kvm_vcpu *vcpu); int kvm_get_apic_interrupt(struct kvm_vcpu *vcpu); +void kvm_apic_accept_events(struct kvm_vcpu *vcpu); void kvm_lapic_reset(struct kvm_vcpu *vcpu); u64 kvm_lapic_get_cr8(struct kvm_vcpu *vcpu); void kvm_lapic_set_tpr(struct kvm_vcpu *vcpu, unsigned long cr8); @@ -158,4 +164,9 @@ void kvm_calculate_eoi_exitmap(struct kvm_vcpu *vcpu, struct kvm_lapic_irq *irq, u64 *eoi_bitmap); +static inline bool kvm_apic_has_events(struct kvm_vcpu *vcpu) +{ + return vcpu->arch.apic->pending_events; +} + #endif diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index 907e4280116d..7219a4012a0e 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -1199,12 +1199,6 @@ static void svm_vcpu_reset(struct kvm_vcpu *vcpu) init_vmcb(svm); - if (!kvm_vcpu_is_bsp(vcpu)) { - kvm_rip_write(vcpu, 0); - svm->vmcb->save.cs.base = svm->vcpu.arch.sipi_vector << 12; - svm->vmcb->save.cs.selector = svm->vcpu.arch.sipi_vector << 8; - } - kvm_cpuid(vcpu, &eax, &dummy, &dummy, &dummy); kvm_register_write(vcpu, VCPU_REGS_RDX, eax); } diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index f588171be177..af1ffaf20892 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -4119,12 +4119,7 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu) vmx_segment_cache_clear(vmx); seg_setup(VCPU_SREG_CS); - if (kvm_vcpu_is_bsp(&vmx->vcpu)) - vmcs_write16(GUEST_CS_SELECTOR, 0xf000); - else { - vmcs_write16(GUEST_CS_SELECTOR, vmx->vcpu.arch.sipi_vector << 8); - vmcs_writel(GUEST_CS_BASE, vmx->vcpu.arch.sipi_vector << 12); - } + vmcs_write16(GUEST_CS_SELECTOR, 0xf000); seg_setup(VCPU_SREG_DS); seg_setup(VCPU_SREG_ES); @@ -4147,10 +4142,7 @@ static void vmx_vcpu_reset(struct kvm_vcpu *vcpu) vmcs_writel(GUEST_SYSENTER_EIP, 0); vmcs_writel(GUEST_RFLAGS, 0x02); - if (kvm_vcpu_is_bsp(&vmx->vcpu)) - kvm_rip_write(vcpu, 0xfff0); - else - kvm_rip_write(vcpu, 0); + kvm_rip_write(vcpu, 0xfff0); vmcs_writel(GUEST_GDTR_BASE, 0); vmcs_write32(GUEST_GDTR_LIMIT, 0xffff); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index fadd5a750476..61a5bb60af86 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -162,8 +162,6 @@ u64 __read_mostly host_xcr0; static int emulator_fix_hypercall(struct x86_emulate_ctxt *ctxt); -static void kvm_vcpu_reset(struct kvm_vcpu *vcpu); - static inline void kvm_async_pf_hash_reset(struct kvm_vcpu *vcpu) { int i; @@ -2830,10 +2828,9 @@ static void kvm_vcpu_ioctl_x86_get_vcpu_events(struct kvm_vcpu *vcpu, events->nmi.masked = kvm_x86_ops->get_nmi_mask(vcpu); events->nmi.pad = 0; - events->sipi_vector = vcpu->arch.sipi_vector; + events->sipi_vector = 0; /* never valid when reporting to user space */ events->flags = (KVM_VCPUEVENT_VALID_NMI_PENDING - | KVM_VCPUEVENT_VALID_SIPI_VECTOR | KVM_VCPUEVENT_VALID_SHADOW); memset(&events->reserved, 0, sizeof(events->reserved)); } @@ -2864,8 +2861,9 @@ static int kvm_vcpu_ioctl_x86_set_vcpu_events(struct kvm_vcpu *vcpu, vcpu->arch.nmi_pending = events->nmi.pending; kvm_x86_ops->set_nmi_mask(vcpu, events->nmi.masked); - if (events->flags & KVM_VCPUEVENT_VALID_SIPI_VECTOR) - vcpu->arch.sipi_vector = events->sipi_vector; + if (events->flags & KVM_VCPUEVENT_VALID_SIPI_VECTOR && + kvm_vcpu_has_lapic(vcpu)) + vcpu->arch.apic->sipi_vector = events->sipi_vector; kvm_make_request(KVM_REQ_EVENT, vcpu); @@ -5720,6 +5718,12 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) } if (kvm_check_request(KVM_REQ_EVENT, vcpu) || req_int_win) { + kvm_apic_accept_events(vcpu); + if (vcpu->arch.mp_state == KVM_MP_STATE_INIT_RECEIVED) { + r = 1; + goto out; + } + inject_pending_event(vcpu); /* enable NMI/IRQ window open exits if needed */ @@ -5854,14 +5858,6 @@ static int __vcpu_run(struct kvm_vcpu *vcpu) int r; struct kvm *kvm = vcpu->kvm; - if (unlikely(vcpu->arch.mp_state == KVM_MP_STATE_SIPI_RECEIVED)) { - pr_debug("vcpu %d received sipi with vector # %x\n", - vcpu->vcpu_id, vcpu->arch.sipi_vector); - kvm_lapic_reset(vcpu); - kvm_vcpu_reset(vcpu); - vcpu->arch.mp_state = KVM_MP_STATE_RUNNABLE; - } - vcpu->srcu_idx = srcu_read_lock(&kvm->srcu); r = vapic_enter(vcpu); if (r) { @@ -5878,8 +5874,8 @@ static int __vcpu_run(struct kvm_vcpu *vcpu) srcu_read_unlock(&kvm->srcu, vcpu->srcu_idx); kvm_vcpu_block(vcpu); vcpu->srcu_idx = srcu_read_lock(&kvm->srcu); - if (kvm_check_request(KVM_REQ_UNHALT, vcpu)) - { + if (kvm_check_request(KVM_REQ_UNHALT, vcpu)) { + kvm_apic_accept_events(vcpu); switch(vcpu->arch.mp_state) { case KVM_MP_STATE_HALTED: vcpu->arch.mp_state = @@ -5887,7 +5883,8 @@ static int __vcpu_run(struct kvm_vcpu *vcpu) case KVM_MP_STATE_RUNNABLE: vcpu->arch.apf.halted = false; break; - case KVM_MP_STATE_SIPI_RECEIVED: + case KVM_MP_STATE_INIT_RECEIVED: + break; default: r = -EINTR; break; @@ -6022,6 +6019,7 @@ int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run) if (unlikely(vcpu->arch.mp_state == KVM_MP_STATE_UNINITIALIZED)) { kvm_vcpu_block(vcpu); + kvm_apic_accept_events(vcpu); clear_bit(KVM_REQ_UNHALT, &vcpu->requests); r = -EAGAIN; goto out; @@ -6178,6 +6176,7 @@ int kvm_arch_vcpu_ioctl_get_sregs(struct kvm_vcpu *vcpu, int kvm_arch_vcpu_ioctl_get_mpstate(struct kvm_vcpu *vcpu, struct kvm_mp_state *mp_state) { + kvm_apic_accept_events(vcpu); mp_state->mp_state = vcpu->arch.mp_state; return 0; } @@ -6185,7 +6184,15 @@ int kvm_arch_vcpu_ioctl_get_mpstate(struct kvm_vcpu *vcpu, int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu, struct kvm_mp_state *mp_state) { - vcpu->arch.mp_state = mp_state->mp_state; + if (!kvm_vcpu_has_lapic(vcpu) && + mp_state->mp_state != KVM_MP_STATE_RUNNABLE) + return -EINVAL; + + if (mp_state->mp_state == KVM_MP_STATE_SIPI_RECEIVED) { + vcpu->arch.mp_state = KVM_MP_STATE_INIT_RECEIVED; + set_bit(KVM_APIC_SIPI, &vcpu->arch.apic->pending_events); + } else + vcpu->arch.mp_state = mp_state->mp_state; kvm_make_request(KVM_REQ_EVENT, vcpu); return 0; } @@ -6522,7 +6529,7 @@ void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu) kvm_x86_ops->vcpu_free(vcpu); } -static void kvm_vcpu_reset(struct kvm_vcpu *vcpu) +void kvm_vcpu_reset(struct kvm_vcpu *vcpu) { atomic_set(&vcpu->arch.nmi_queued, 0); vcpu->arch.nmi_pending = 0; @@ -6552,6 +6559,17 @@ static void kvm_vcpu_reset(struct kvm_vcpu *vcpu) kvm_x86_ops->vcpu_reset(vcpu); } +void kvm_vcpu_deliver_sipi_vector(struct kvm_vcpu *vcpu, unsigned int vector) +{ + struct kvm_segment cs; + + kvm_get_segment(vcpu, &cs, VCPU_SREG_CS); + cs.selector = vector << 8; + cs.base = vector << 12; + kvm_set_segment(vcpu, &cs, VCPU_SREG_CS); + kvm_rip_write(vcpu, 0); +} + int kvm_arch_hardware_enable(void *garbage) { struct kvm *kvm; @@ -6995,7 +7013,7 @@ int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu) return (vcpu->arch.mp_state == KVM_MP_STATE_RUNNABLE && !vcpu->arch.apf.halted) || !list_empty_careful(&vcpu->async_pf.done) - || vcpu->arch.mp_state == KVM_MP_STATE_SIPI_RECEIVED + || kvm_apic_has_events(vcpu) || atomic_read(&vcpu->arch.nmi_queued) || (kvm_arch_interrupt_allowed(vcpu) && kvm_cpu_has_interrupt(vcpu)); -- 2.39.5