This patch implements the doorbell msr emulation for nested AVIC.
Signed-off-by: Maxim Levitsky mlevitsk@redhat.com --- arch/x86/kvm/svm/avic.c | 49 +++++++++++++++++++++++++++++++++++++++++ arch/x86/kvm/svm/svm.c | 2 ++ arch/x86/kvm/svm/svm.h | 1 + 3 files changed, 52 insertions(+)
diff --git a/arch/x86/kvm/svm/avic.c b/arch/x86/kvm/svm/avic.c index e8c53fd77f0b1..149df26e17462 100644 --- a/arch/x86/kvm/svm/avic.c +++ b/arch/x86/kvm/svm/avic.c @@ -1165,6 +1165,55 @@ unsigned long avic_vcpu_get_apicv_inhibit_reasons(struct kvm_vcpu *vcpu) return 0; }
+int avic_emulate_doorbell_write(struct kvm_vcpu *vcpu, u64 data) +{ + int source_l1_apicid = vcpu->vcpu_id; + int target_l1_apicid = data & AVIC_DOORBELL_PHYSICAL_ID_MASK; + bool target_running, target_nested; + struct kvm_vcpu *target; + struct vcpu_svm *svm = to_svm(vcpu); + + if (!svm->avic_enabled || (data & ~AVIC_DOORBELL_PHYSICAL_ID_MASK)) + return 1; + + target = avic_vcpu_by_l1_apicid(vcpu->kvm, target_l1_apicid); + if (!target) + /* Guest bug: targeting invalid APIC ID. */ + return 0; + + target_running = READ_ONCE(target->mode) == IN_GUEST_MODE; + target_nested = is_guest_mode(target); + + trace_kvm_avic_nested_doorbell(source_l1_apicid, target_l1_apicid, + target_nested, target_running); + + /* + * Target is not in the nested mode, thus the doorbell doesn't affect it. + * If it just became nested after is_guest_mode was checked, + * it means that it just processed AVIC state and KVM doesn't need + * to send it another doorbell. + */ + if (!target_nested) + return 0; + + /* + * If the target vCPU is in guest mode, kick the real doorbell. + * Otherwise KVM needs to try to wake it up if it was sleeping. + * + * If the target is not longer in guest mode (just exited it), + * it will either halt and before that it will notice pending IRR + * bits, and cancel halting, or it will enter the guest mode again, + * and notice the IRR bits as well. + */ + if (target_running) + wrmsr(MSR_AMD64_SVM_AVIC_DOORBELL, + kvm_cpu_get_apicid(READ_ONCE(target->cpu)), 0); + else + kvm_vcpu_wake_up(target); + + return 0; +} + static u32 *avic_get_logical_id_entry(struct kvm_vcpu *vcpu, u32 ldr, bool flat) { struct kvm_svm *kvm_svm = to_kvm_svm(vcpu->kvm); diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index d96a73931d1e5..b31bab832360e 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -2772,6 +2772,8 @@ static int svm_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr) u32 ecx = msr->index; u64 data = msr->data; switch (ecx) { + case MSR_AMD64_SVM_AVIC_DOORBELL: + return avic_emulate_doorbell_write(vcpu, data); case MSR_AMD64_TSC_RATIO:
if (!svm->tsc_scaling_enabled) { diff --git a/arch/x86/kvm/svm/svm.h b/arch/x86/kvm/svm/svm.h index 93fd9d6f5fd85..14e2c5c451cad 100644 --- a/arch/x86/kvm/svm/svm.h +++ b/arch/x86/kvm/svm/svm.h @@ -714,6 +714,7 @@ unsigned long avic_vcpu_get_apicv_inhibit_reasons(struct kvm_vcpu *vcpu); void avic_reload_apic_pages(struct kvm_vcpu *vcpu); void avic_free_nested(struct kvm_vcpu *vcpu); bool avic_nested_has_interrupt(struct kvm_vcpu *vcpu); +int avic_emulate_doorbell_write(struct kvm_vcpu *vcpu, u64 data);
struct avic_physid_table * avic_physid_shadow_table_get(struct kvm_vcpu *vcpu, gfn_t gfn);