From 305d0ab4764d36a02c8e7cddb67099aca65351ce Mon Sep 17 00:00:00 2001 From: Wanpeng Li Date: Thu, 28 Sep 2017 18:16:44 -0700 Subject: [PATCH] KVM: nVMX: Fix nested #PF intends to break L1's vmlauch/vmresume MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit ------------[ cut here ]------------ WARNING: CPU: 4 PID: 5280 at /home/kernel/linux/arch/x86/kvm//vmx.c:11394 nested_vmx_vmexit+0xc2b/0xd70 [kvm_intel] CPU: 4 PID: 5280 Comm: qemu-system-x86 Tainted: G W OE 4.13.0+ #17 RIP: 0010:nested_vmx_vmexit+0xc2b/0xd70 [kvm_intel] Call Trace: ? emulator_read_emulated+0x15/0x20 [kvm] ? segmented_read+0xae/0xf0 [kvm] vmx_inject_page_fault_nested+0x60/0x70 [kvm_intel] ? vmx_inject_page_fault_nested+0x60/0x70 [kvm_intel] x86_emulate_instruction+0x733/0x810 [kvm] vmx_handle_exit+0x2f4/0xda0 [kvm_intel] ? kvm_arch_vcpu_ioctl_run+0xd2f/0x1c60 [kvm] kvm_arch_vcpu_ioctl_run+0xdab/0x1c60 [kvm] ? kvm_arch_vcpu_load+0x62/0x230 [kvm] kvm_vcpu_ioctl+0x340/0x700 [kvm] ? kvm_vcpu_ioctl+0x340/0x700 [kvm] ? __fget+0xfc/0x210 do_vfs_ioctl+0xa4/0x6a0 ? __fget+0x11d/0x210 SyS_ioctl+0x79/0x90 entry_SYSCALL_64_fastpath+0x23/0xc2 A nested #PF is triggered during L0 emulating instruction for L2. However, it doesn't consider we should not break L1's vmlauch/vmresme. This patch fixes it by queuing the #PF exception instead ,requesting an immediate VM exit from L2 and keeping the exception for L1 pending for a subsequent nested VM exit. This should actually work all the time, making vmx_inject_page_fault_nested totally unnecessary. However, that's not working yet, so this patch can work around the issue in the meanwhile. Cc: Paolo Bonzini Cc: Radim Krčmář Signed-off-by: Wanpeng Li Signed-off-by: Paolo Bonzini --- arch/x86/kvm/vmx.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c index 7f62c94196d1..5bfa353f6354 100644 --- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -9845,7 +9845,8 @@ static void vmx_inject_page_fault_nested(struct kvm_vcpu *vcpu, WARN_ON(!is_guest_mode(vcpu)); - if (nested_vmx_is_page_fault_vmexit(vmcs12, fault->error_code)) { + if (nested_vmx_is_page_fault_vmexit(vmcs12, fault->error_code) && + !to_vmx(vcpu)->nested.nested_run_pending) { vmcs12->vm_exit_intr_error_code = fault->error_code; nested_vmx_vmexit(vcpu, EXIT_REASON_EXCEPTION_NMI, PF_VECTOR | INTR_TYPE_HARD_EXCEPTION | -- 2.20.1