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. Signed-off-by: Jan Kiszka <[email protected]> --- This doesn't fix the wrong behaviour on INIT for the BSP yet. Leaving this honor to Paolo. I didn't try porting any INIT handling for nested on top yet but I think it should be feasible - once we know their semantics for sure, at least on Intel... arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/lapic.c | 41 +++++++++++++++++++++++++++++++------- arch/x86/kvm/lapic.h | 7 ++++++ arch/x86/kvm/x86.c | 39 ++++++++++++++++++++---------------- 4 files changed, 63 insertions(+), 25 deletions(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index 348d859..2d28e76 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -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 02b51dd..4a21a6b 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -731,7 +731,7 @@ 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; + set_bit(KVM_APIC_INIT, &apic->pending_events); kvm_make_request(KVM_REQ_EVENT, vcpu); kvm_vcpu_kick(vcpu); } else { @@ -743,13 +743,13 @@ 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 +1860,31 @@ int kvm_lapic_enable_pv_eoi(struct kvm_vcpu *vcpu, u64 data) addr); } +bool kvm_apic_has_events(struct kvm_vcpu *vcpu) +{ + return kvm_vcpu_has_lapic(vcpu) && vcpu->arch.apic->pending_events; +} + +void kvm_apic_accept_events(struct kvm_vcpu *vcpu) +{ + struct kvm_lapic *apic = vcpu->arch.apic; + + if (!kvm_vcpu_has_lapic(vcpu)) + return; + + if (test_and_clear_bit(KVM_APIC_INIT, &apic->pending_events)) + 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) { + vcpu->arch.sipi_vector = apic->sipi_vector; + 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; + } +} + 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 1676d34..ef3f4ef 100644 --- a/arch/x86/kvm/lapic.h +++ b/arch/x86/kvm/lapic.h @@ -5,6 +5,9 @@ #include <linux/kvm_host.h> +#define KVM_APIC_INIT 0 +#define KVM_APIC_SIPI 1 + struct kvm_timer { struct hrtimer timer; s64 period; /* unit: ns */ @@ -32,13 +35,17 @@ 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); int kvm_apic_has_interrupt(struct kvm_vcpu *vcpu); +bool kvm_apic_has_events(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); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index b891ac3..a0b8041 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; @@ -5663,6 +5661,11 @@ static int vcpu_enter_guest(struct kvm_vcpu *vcpu) bool req_immediate_exit = 0; if (vcpu->requests) { + kvm_apic_accept_events(vcpu); + if (vcpu->arch.mp_state == KVM_MP_STATE_INIT_RECEIVED) { + r = 1; + goto out; + } if (kvm_check_request(KVM_REQ_MMU_RELOAD, vcpu)) kvm_mmu_unload(vcpu); if (kvm_check_request(KVM_REQ_MIGRATE_TIMER, vcpu)) @@ -5847,14 +5850,6 @@ 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) { @@ -5871,8 +5866,8 @@ 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 = @@ -5880,7 +5875,8 @@ 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; @@ -5901,7 +5897,8 @@ static int __vcpu_run(struct kvm_vcpu *vcpu) ++vcpu->stat.request_irq_exits; } - kvm_check_async_pf_completion(vcpu); + if (vcpu->arch.mp_state != KVM_MP_STATE_INIT_RECEIVED) + kvm_check_async_pf_completion(vcpu); if (signal_pending(current)) { r = -EINTR; @@ -6015,6 +6012,7 @@ 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; @@ -6171,6 +6169,7 @@ 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; } @@ -6178,7 +6177,13 @@ 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 (mp_state->mp_state == KVM_MP_STATE_SIPI_RECEIVED) { + if (!kvm_vcpu_has_lapic(vcpu)) + return -EINVAL; + 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; } @@ -6515,7 +6520,7 @@ 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; @@ -6988,7 +6993,7 @@ 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)); 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