This is a note to let you know that I've just added the patch titled
KVM: nVMX: reset nested_run_pending if the vCPU is going to be reset
to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: kvm-nvmx-reset-nested_run_pending-if-the-vcpu-is-going-to-be-reset.patch and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
From foo@baz Tue Dec 12 13:38:50 CET 2017
From: Wanpeng Li wanpeng.li@hotmail.com Date: Mon, 6 Mar 2017 04:03:28 -0800 Subject: KVM: nVMX: reset nested_run_pending if the vCPU is going to be reset
From: Wanpeng Li wanpeng.li@hotmail.com
[ Upstream commit 2f707d97982286b307ef2a9b034e19aabc1abb56 ]
Reported by syzkaller:
WARNING: CPU: 1 PID: 27742 at arch/x86/kvm/vmx.c:11029 nested_vmx_vmexit+0x5c35/0x74d0 arch/x86/kvm/vmx.c:11029 CPU: 1 PID: 27742 Comm: a.out Not tainted 4.10.0+ #229 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:15 [inline] dump_stack+0x2ee/0x3ef lib/dump_stack.c:51 panic+0x1fb/0x412 kernel/panic.c:179 __warn+0x1c4/0x1e0 kernel/panic.c:540 warn_slowpath_null+0x2c/0x40 kernel/panic.c:583 nested_vmx_vmexit+0x5c35/0x74d0 arch/x86/kvm/vmx.c:11029 vmx_leave_nested arch/x86/kvm/vmx.c:11136 [inline] vmx_set_msr+0x1565/0x1910 arch/x86/kvm/vmx.c:3324 kvm_set_msr+0xd4/0x170 arch/x86/kvm/x86.c:1099 do_set_msr+0x11e/0x190 arch/x86/kvm/x86.c:1128 __msr_io arch/x86/kvm/x86.c:2577 [inline] msr_io+0x24b/0x450 arch/x86/kvm/x86.c:2614 kvm_arch_vcpu_ioctl+0x35b/0x46a0 arch/x86/kvm/x86.c:3497 kvm_vcpu_ioctl+0x232/0x1120 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2721 vfs_ioctl fs/ioctl.c:43 [inline] do_vfs_ioctl+0x1bf/0x1790 fs/ioctl.c:683 SYSC_ioctl fs/ioctl.c:698 [inline] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:689 entry_SYSCALL_64_fastpath+0x1f/0xc2
The syzkaller folks reported a nested_run_pending warning during userspace clear VMX capability which is exposed to L1 before.
The warning gets thrown while doing
(*(uint32_t*)0x20aecfe8 = (uint32_t)0x1); (*(uint32_t*)0x20aecfec = (uint32_t)0x0); (*(uint32_t*)0x20aecff0 = (uint32_t)0x3a); (*(uint32_t*)0x20aecff4 = (uint32_t)0x0); (*(uint64_t*)0x20aecff8 = (uint64_t)0x0); r[29] = syscall(__NR_ioctl, r[4], 0x4008ae89ul, 0x20aecfe8ul, 0, 0, 0, 0, 0, 0);
i.e. KVM_SET_MSR ioctl with
struct kvm_msrs { .nmsrs = 1, .pad = 0, .entries = { {.index = MSR_IA32_FEATURE_CONTROL, .reserved = 0, .data = 0} } }
The VMLANCH/VMRESUME emulation should be stopped since the CPU is going to reset here. This patch resets the nested_run_pending since the CPU is going to be reset hence there should be nothing pending.
Reported-by: Dmitry Vyukov dvyukov@google.com Suggested-by: Radim Krčmář rkrcmar@redhat.com Cc: Paolo Bonzini pbonzini@redhat.com Cc: Radim Krčmář rkrcmar@redhat.com Cc: Dmitry Vyukov dvyukov@google.com Cc: David Hildenbrand david@redhat.com Signed-off-by: Wanpeng Li wanpeng.li@hotmail.com Reviewed-by: David Hildenbrand david@redhat.com Reviewed-by: Jim Mattson jmattson@google.com Signed-off-by: Radim Krčmář rkrcmar@redhat.com Signed-off-by: Sasha Levin alexander.levin@verizon.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/x86/kvm/vmx.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -10555,8 +10555,10 @@ static void nested_vmx_vmexit(struct kvm */ static void vmx_leave_nested(struct kvm_vcpu *vcpu) { - if (is_guest_mode(vcpu)) + if (is_guest_mode(vcpu)) { + to_vmx(vcpu)->nested.nested_run_pending = 0; nested_vmx_vmexit(vcpu, -1, 0, 0); + } free_nested(to_vmx(vcpu)); }
Patches currently in stable-queue which might be from wanpeng.li@hotmail.com are
queue-4.4/kvm-nvmx-reset-nested_run_pending-if-the-vcpu-is-going-to-be-reset.patch