linux-kernel - Re: VMs freezing when host is running 4.14

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Date:   Thu, 23 Nov 2017 16:20:24 +0100
From:   Marc Haber <mh+linux-kernel@...schlus.de>
To:     Radim Krčmář <rkrcmar@...hat.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        "KVM-ML (kvm@...r.kernel.org)" <kvm@...r.kernel.org>,
        Wanpeng Li <kernellwp@...il.com>
Subject: Re: VMs freezing when host is running 4.14

On Wed, Nov 22, 2017 at 05:43:13PM +0100, Radim Krčmář wrote:
> 2017-11-22 16:52+0100, Marc Haber:
> > On Wed, Nov 22, 2017 at 04:04:42PM +0100, 王金浦 wrote:
> > > So all guest kernels are 4.14, or also other older kernel?
> > 
> > Guest kernels are also 4.14, but the issue disappears when the host is
> > downgraded to an older kernel. I therefore reckoned that the guest
> > kernel doesn't matter, but that was before I saw the trace in the log.
> 
> The two most suspicious patches since 4.13 (which I assume works) are
> 
>   664f8e26b00c ("KVM: X86: Fix loss of exception which has not yet been
>   injected")

That one does not revert cleanly, the line in questions seems to have
been removed a bit later.

Reject is:
141 [24/5001]mh@fan:~/linux/git/linux ((v4.14.1) %) $ cat arch/x86/kvm/vmx.c.rej--- arch/x86/kvm/vmx.c
+++ arch/x86/kvm/vmx.c
@@ -2516,7 +2516,7 @@ static void vmx_queue_exception(struct kvm_vcpu *vcpu)
        struct vcpu_vmx *vmx = to_vmx(vcpu);
        unsigned nr = vcpu->arch.exception.nr;
        bool has_error_code = vcpu->arch.exception.has_error_code;
-       bool reinject = vcpu->arch.exception.injected;
+       bool reinject = vcpu->arch.exception.reinject;
        u32 error_code = vcpu->arch.exception.error_code;
        u32 intr_info = nr | INTR_INFO_VALID_MASK;

> 
> and
> 
>   9a6e7c39810e ("KVM: async_pf: Fix #DF due to inject "Page not Present"
>   and "Page Ready" exceptions simultaneously")
> 
> please try reverting them to see if it helps,

That one reverted cleanly. I am now running the new kernel on the
affected machine, and I think that a second machine has joined the
market of being affected.

Would this matter on the host only or on the guests as well?

Greetings
Marc

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