On 23/01/2017 17:03, David Hildenbrand wrote: > Am 22.01.2017 um 09:52 schrieb Dmitry Vyukov: >> On Sat, Nov 12, 2016 at 2:56 AM, Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote: >>> Hello, >>> >>> The following program triggers WARNING in kvm_apic_accept_events: >>> https://gist.githubusercontent.com/dvyukov/95b845a2e637485568ea1ef181a72370/raw/d90717dd67128b21715c5e794568a1600f613d97/gistfile1.txt >>> >>> On commit 015ed9433be2b476ec7e2e6a9a411a56e3b5b035 (Nov 11). >>> >>> ------------[ cut here ]------------ >>> WARNING: CPU: 1 PID: 23523 at arch/x86/kvm/lapic.c:2330 >>> kvm_apic_accept_events+0x3f6/0x460 >>> Modules linked in:[ 55.632648] CPU: 1 PID: 2812 Comm: a.out Not >>> tainted 4.9.0-rc4+ #41 >>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011 >>> ffff88006be77978 ffffffff81c2f79b 0000000000000000 0000000000000000 >>> ffffffff8322d6a0 ffffffff81127426 ffff88006be779c0 ffffffff8123ffef >>> ffffffff811acc46 ffffffff0000091a ffffffff8322d6a0 000000000000091a >>> Call Trace: >>> [< inline >] __dump_stack lib/dump_stack.c:15 >>> [<ffffffff81c2f79b>] dump_stack+0xb3/0x118 lib/dump_stack.c:51 >>> [<ffffffff8123ffef>] __warn+0x19f/0x1e0 kernel/panic.c:550 >>> [<ffffffff812401fc>] warn_slowpath_null+0x2c/0x40 kernel/panic.c:585 >>> [<ffffffff81127426>] kvm_apic_accept_events+0x3f6/0x460 >>> arch/x86/kvm/lapic.c:2330 >>> [< inline >] vcpu_block arch/x86/kvm/x86.c:6793 >>> [< inline >] vcpu_run arch/x86/kvm/x86.c:6828 >>> [<ffffffff810b8f20>] kvm_arch_vcpu_ioctl_run+0x1580/0x5a90 >>> arch/x86/kvm/x86.c:6984 >>> [<ffffffff8106091e>] kvm_vcpu_ioctl+0x61e/0xdd0 >>> arch/x86/kvm/../../../virt/kvm/kvm_main.c:2557 >>> [< inline >] vfs_ioctl fs/ioctl.c:43 >>> [<ffffffff816b16fc>] do_vfs_ioctl+0x18c/0x1040 fs/ioctl.c:679 >>> [< inline >] SYSC_ioctl fs/ioctl.c:694 >>> [<ffffffff816b263f>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685 >>> [<ffffffff831ebd01>] entry_SYSCALL_64_fastpath+0x1f/0xc2 >>> arch/x86/entry/entry_64.S:209 >>> ---[ end trace b2415ddd1b26dce6 ]--- >> >> >> ping >> > > Our VCPU is in SMM mode but is switched into KVM_MP_STATE_INIT_RECEIVED. > > The relevant warning is (arch/x86/kvm/lapic.c:kvm_apic_accept_events()) > > if (is_smm(vcpu)) { > WARN_ON_ONCE(vcpu->arch.mp_state == KVM_MP_STATE_INIT_RECEIVED); > .... > > Something like that might help (untested): > > > From: David Hildenbrand <david@xxxxxxxxxx> > Date: Mon, 23 Jan 2017 16:42:23 +0100 > Subject: [PATCH] KVM: x86: fix illegal MP_STATE when in/entering SMM > > If we already entered/are about to enter SMM, don't allow > switching to INIT/SIPI_RECEIVED, otherwise the next call to > kvm_apic_accept_events() will report a warning. > > Fixes: cd7764fe9f73 ("KVM: x86: latch INITs while in system management mode") > Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx> > Signed-off-by: David Hildenbrand <david@xxxxxxxxxx> > --- > arch/x86/kvm/x86.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 57d8a85..06ffc91 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -7247,6 +7247,12 @@ int kvm_arch_vcpu_ioctl_set_mpstate(struct kvm_vcpu *vcpu, > mp_state->mp_state != KVM_MP_STATE_RUNNABLE) > return -EINVAL; > > + /* INITs are latched while in SMM */ > + if ((is_smm(vcpu) || vcpu->arch.smi_pending) && > + (mp_state->mp_state == KVM_MP_STATE_SIPI_RECEIVED || > + mp_state->mp_state == KVM_MP_STATE_INIT_RECEIVED)) > + return -EINVAL; > + > if (mp_state->mp_state == KVM_MP_STATE_SIPI_RECEIVED) { > vcpu->arch.mp_state = KVM_MP_STATE_INIT_RECEIVED; > set_bit(KVM_APIC_SIPI, &vcpu->arch.apic->pending_events); > Looks good, thanks for analyzing it. I'll try making a minimal testcase... Paolo
