From b9a1254c31cc63d1f30fa37b782ebab70e9f0665 Mon Sep 17 00:00:00 2001 From: Wanpeng Li Date: Mon, 5 Jun 2017 05:19:09 -0700 Subject: [PATCH] KVM: nVMX: Fix exception injection MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit commit d4912215d1031e4fb3d1038d2e1857218dba0d0a upstream. 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. 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. Cc: Paolo Bonzini Cc: Radim Krčmář Signed-off-by: Wanpeng Li Fixes: e011c663b9c7 ("KVM: nVMX: Check all exceptions for intercept during delivery to L2") Signed-off-by: Radim Krčmář Signed-off-by: Greg Kroah-Hartman --- 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 259e9b28ccf8..e06ec5333da1 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -2436,7 +2436,7 @@ 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; -- 2.11.4.GIT