Gleb Natapov wrote:
> On Sun, Sep 21, 2008 at 06:57:32PM +0200, Jan Kiszka wrote:
>> Gleb Natapov wrote:
>>> Hi Jan,
>>>
>>> On Fri, Sep 19, 2008 at 02:04:37PM +0200, Jan Kiszka wrote:
>>>> static void vmx_inject_irq(struct kvm_vcpu *vcpu, int irq)
>>>> {
>>>> struct vcpu_vmx *vmx = to_vmx(vcpu);
>>>> @@ -2356,6 +2384,29 @@ static void vmx_inject_nmi(struct kvm_vc
>>>> {
>>>> struct vcpu_vmx *vmx = to_vmx(vcpu);
>>>>
>>>> + if (!cpu_has_virtual_nmis()) {
>>>> + int desc_size = is_long_mode(vcpu) ? 16 : 8;
>>>> + struct descriptor_table dt;
>>>> + gpa_t gpa;
>>>> + u64 desc;
>>>> +
>>>> + /*
>>>> + * Deny delivery if the NMI will not be handled by an
>>>> + * interrupt gate (workaround depends on IRQ masking).
>>>> + */
>>>> + vmx_get_idt(vcpu, &dt);
>>>> + if (!vcpu->arch.rmode.active && dt.limit
>>>> + >= desc_size * (NMI_VECTOR + 1) - 1) {
>>>> + gpa = vcpu->arch.mmu.gva_to_gpa(vcpu,
>>>> + dt.base + desc_size * NMI_VECTOR);
>>>> + if (kvm_read_guest(vcpu->kvm, gpa, &desc, 8) == 0
>>>> + && ((desc >> 40) & 0x7) != 0x6)
>>>> + return;
>>>> + }
>>> Windows2003 sets NMI entry in IDT as a task gate (0x5) during hibernation
>>> and this check
>>> prevents it from shutting down itself. It hangs in "It is save to turn
>>> your computer now" screen.
>> Grmbl, what a weird guest...
> This is a known trick that some OSes use.OK. Out of curiosity: What is that trick precisely? > >> Is this a regression of this patch because NMIs were considered broken >> by Windows on that host CPU so far? >> > Nope. This is not a regression. Hibernation hangs in the same place with > the current git on this machine. It works on newer CPUs. > > >>> If I replace this part by: >>> if(vmx->soft_vnmi_blocked) >>> return; >>> It shut itself down properly. >> OK, but that almost always evaluates to false here. > Without this check guest BSODs. CPU 0 send two NMI in a row to CPU 1 and > if second one is accepted something goes wrong. That should have been caught at the caller site of vmx_inject_nmi already, having to catch it here is an indication of a deeper problem. Are you sure the NMIs are sent by CPU (i.e. kvm_inject_nmi is called twice)? Maybe it is a bug I fixed meanwhile, an updated series goes out later this morning. Jan
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