From 1459f5c6b8b8dfbc16adf4844421d46459c9ab1f Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Fri, 6 Jan 2023 01:12:41 +0000 Subject: [PATCH] KVM: x86: Handle APICv updates for APIC "mode" changes via request Use KVM_REQ_UPDATE_APICV to react to APIC "mode" changes, i.e. to handle the APIC being hardware enabled/disabled and/or x2APIC being toggled. There is no need to immediately update APICv state, the only requirement is that APICv be updating prior to the next VM-Enter. Making a request will allow piggybacking KVM_REQ_UPDATE_APICV to "inhibit" the APICv memslot when x2APIC is enabled. Doing that directly from kvm_lapic_set_base() isn't feasible as KVM's SRCU must not be held when modifying memslots (to avoid deadlock), and may or may not be held when kvm_lapic_set_base() is called, i.e. KVM can't do the right thing without tracking that is rightly buried behind CONFIG_PROVE_RCU=y. Suggested-by: Maxim Levitsky Reviewed-by: Maxim Levitsky Signed-off-by: Sean Christopherson Message-Id: <20230106011306.85230-9-seanjc@google.com> Signed-off-by: Paolo Bonzini --- arch/x86/kvm/lapic.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 2183a9b8efa5..3ed74ad60516 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -2401,7 +2401,7 @@ void kvm_lapic_set_base(struct kvm_vcpu *vcpu, u64 value) kvm_apic_set_x2apic_id(apic, vcpu->vcpu_id); if ((old_value ^ value) & (MSR_IA32_APICBASE_ENABLE | X2APIC_ENABLE)) { - kvm_vcpu_update_apicv(vcpu); + kvm_make_request(KVM_REQ_APICV_UPDATE, vcpu); static_call_cond(kvm_x86_set_virtual_apic_mode)(vcpu); }