On 05/06/2017 14:19, Wanpeng Li wrote: > From: Wanpeng Li <wanpeng.li@xxxxxxxxxxx> > > WARNING: CPU: 3 PID: 2840 at arch/x86/kvm/vmx.c:10966 nested_vmx_vmexit+0xdcd/0xde0 [kvm_intel] > CPU: 3 PID: 2840 Comm: qemu-system-x86 Tainted: G OE 4.12.0-rc3+ #23 > RIP: 0010:nested_vmx_vmexit+0xdcd/0xde0 [kvm_intel] > Call Trace: > ? kvm_check_async_pf_completion+0xef/0x120 [kvm] > ? rcu_read_lock_sched_held+0x79/0x80 > vmx_queue_exception+0x104/0x160 [kvm_intel] > ? vmx_queue_exception+0x104/0x160 [kvm_intel] > kvm_arch_vcpu_ioctl_run+0x1171/0x1ce0 [kvm] > ? kvm_arch_vcpu_load+0x47/0x240 [kvm] > ? kvm_arch_vcpu_load+0x62/0x240 [kvm] > kvm_vcpu_ioctl+0x384/0x7b0 [kvm] > ? kvm_vcpu_ioctl+0x384/0x7b0 [kvm] > ? __fget+0xf3/0x210 > do_vfs_ioctl+0xa4/0x700 > ? __fget+0x114/0x210 > SyS_ioctl+0x79/0x90 > do_syscall_64+0x81/0x220 > entry_SYSCALL64_slow_path+0x25/0x25 > > This is triggered occasionally by running both win7 and win2016 in L2, in > addition, EPT is disabled on both L1 and L2. It can't be reproduced easily. > > Commit 0b6ac343fc (KVM: nVMX: Correct handling of exception injection) mentioned > that "KVM wants to inject page-faults which it got to the guest. This function > assumes it is called with the exit reason in vmcs02 being a #PF exception". > Commit e011c663 (KVM: nVMX: Check all exceptions for intercept during delivery to > L2) allows to check all exceptions for intercept during delivery to L2. However, > there is no guarantee the exit reason is exception currently, when there is an > external interrupt occurred on host, maybe a time interrupt for host which should > not be injected to guest, and somewhere queues an exception, then the function > nested_vmx_check_exception() will be called and the vmexit emulation codes will > try to emulate the "Acknowledge interrupt on exit" behavior, the warning is > triggered. > > This patch fixes it by confirming to inject exception to the guest when the exit > reason in vmcs02 is exception. I think the final part of the commit message needs to be reworded, like: Reusing the exit reason from the L2->L0 vmexit is wrong in this case, the reason must always be EXCEPTION_NMI when injecting an exception into L1 as a nested vmexit. Radim can fix it when applying. Paolo > Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx> > Cc: Radim Krčmář <rkrcmar@xxxxxxxxxx> > Signed-off-by: Wanpeng Li <wanpeng.li@xxxxxxxxxxx> > --- > v1 -> v2: > * pass EXIT_REASON_EXCEPTION_NMI instead of reusing to_vmx(vcpu)->exit_reason > > arch/x86/kvm/vmx.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 9b4b5d6..ca5d2b9 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -2425,7 +2425,7 @@ static int nested_vmx_check_exception(struct kvm_vcpu *vcpu, unsigned nr) > if (!(vmcs12->exception_bitmap & (1u << nr))) > return 0; > > - nested_vmx_vmexit(vcpu, to_vmx(vcpu)->exit_reason, > + nested_vmx_vmexit(vcpu, EXIT_REASON_EXCEPTION_NMI, > vmcs_read32(VM_EXIT_INTR_INFO), > vmcs_readl(EXIT_QUALIFICATION)); > return 1; >
