2017-08-17 18:30-0700, Wanpeng Li: > From: Wanpeng Li <wanpeng.li@xxxxxxxxxxx> > > ------------[ cut here ]------------ > WARNING: CPU: 7 PID: 3861 at /home/kernel/ssd/kvm/arch/x86/kvm//vmx.c:11299 nested_vmx_vmexit+0x176e/0x1980 [kvm_intel] > CPU: 7 PID: 3861 Comm: qemu-system-x86 Tainted: G W OE 4.13.0-rc4+ #11 > RIP: 0010:nested_vmx_vmexit+0x176e/0x1980 [kvm_intel] > Call Trace: > ? kvm_multiple_exception+0x149/0x170 [kvm] > ? handle_emulation_failure+0x79/0x230 [kvm] > ? load_vmcs12_host_state+0xa80/0xa80 [kvm_intel] > ? check_chain_key+0x137/0x1e0 > ? reexecute_instruction.part.168+0x130/0x130 [kvm] > nested_vmx_inject_exception_vmexit+0xb7/0x100 [kvm_intel] > ? nested_vmx_inject_exception_vmexit+0xb7/0x100 [kvm_intel] > vmx_queue_exception+0x197/0x300 [kvm_intel] > kvm_arch_vcpu_ioctl_run+0x1b0c/0x2c90 [kvm] > ? kvm_arch_vcpu_runnable+0x220/0x220 [kvm] > ? preempt_count_sub+0x18/0xc0 > ? restart_apic_timer+0x17d/0x300 [kvm] > ? kvm_lapic_restart_hv_timer+0x37/0x50 [kvm] > ? kvm_arch_vcpu_load+0x1d8/0x350 [kvm] > kvm_vcpu_ioctl+0x4e4/0x910 [kvm] > ? kvm_vcpu_ioctl+0x4e4/0x910 [kvm] > ? kvm_dev_ioctl+0xbe0/0xbe0 [kvm] > > The flag "nested_run_pending", which can override the decision of which should run > next, L1 or L2. nested_run_pending=1 means that we *must* run L2 next, not L1. This > is necessary in particular when L1 did a VMLAUNCH of L2 and therefore expects L2 to > be run (and perhaps be injected with an event it specified, etc.). Nested_run_pending > is especially intended to avoid switching to L1 in the injection decision-point. > > I catch this in the queue exception path, this patch fixes it by running L2 next > instead of L1 in the queue exception path. > > Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> > Cc: Radim Krčmář <rkrcmar@xxxxxxxxxx> > Signed-off-by: Wanpeng Li <wanpeng.li@xxxxxxxxxxx> > --- > arch/x86/kvm/vmx.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index e398946..3e64a9b 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -2466,6 +2466,9 @@ static int nested_vmx_check_exception(struct kvm_vcpu *vcpu) > struct vmcs12 *vmcs12 = get_vmcs12(vcpu); > unsigned int nr = vcpu->arch.exception.nr; > > + if (to_vmx(vcpu)->nested.nested_run_pending) > + return 0; This will inject the exception into L2, even though L1 should get it. We can't return 1 either, as that would just drop the exception ... Seems like we should request an immediate VM exit from L2 and keep the exception for L1 pending for a subsequent nested VM exit. Thanks.
