Merge branch 'kvm-nvmx-and-vm-teardown' into HEAD

The immediate issue being fixed here is a nVMX bug where KVM fails to
detect that, after nested VM-Exit, L1 has a pending IRQ (or NMI).
However, checking for a pending interrupt accesses the legacy PIC, and
x86's kvm_arch_destroy_vm() currently frees the PIC before destroying
vCPUs, i.e. checking for IRQs during the forced nested VM-Exit results
in a NULL pointer deref; that's a prerequisite for the nVMX fix.

The remaining patches attempt to bring a bit of sanity to x86's VM
teardown code, which has accumulated a lot of cruft over the years.  E.g.
KVM currently unloads each vCPU's MMUs in a separate operation from
destroying vCPUs, all because when guest SMP support was added, KVM had a
kludgy MMU teardown flow that broke when a VM had more than one 1 vCPU.
And that oddity lived on, for 18 years...

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

include/linux/kvm_host.h

@@ -1747,7 +1747,6 @@ static inline void kvm_unregister_perf_callbacks(void) {}
 
 int kvm_arch_init_vm(struct kvm *kvm, unsigned long type);
 void kvm_arch_destroy_vm(struct kvm *kvm);
-void kvm_arch_sync_events(struct kvm *kvm);
 
 int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu);