linux-kernel - Re: Qemu e1000 broken in -rc1 and -rc2 : bisected

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Date:	Mon, 09 Mar 2015 11:14:20 +0800
From:	"Chen, Tiejun" <tiejun.chen@...el.com>
To:	Ken Moffat <zarniwhoop@...world.com>,
	Paolo Bonzini <pbonzini@...hat.com>
CC:	linux-kernel@...r.kernel.org
Subject: Re: Qemu e1000 broken in -rc1 and -rc2 : bisected

On 2015/3/7 3:27, Ken Moffat wrote:
> On Fri, Mar 06, 2015 at 12:02:40AM +0000, Ken Moffat wrote:
>>   I have a very recent qemu i686 image, using a 3.19.0 kernel and
>> dhclient, which works fine if the host is running a 3.19.0 kernel,
>> but breaks when the host runs 4.0.0-rc1 or -rc2.
>>
>>   On those, dhclient does not get an address, so I have no network.
>> There is a message
>> e1000 0000:00:03.0 eth0: Reset adaptor
>>
>>   Before I start trying to bisect this, has anybody already seen, or
>> fixed, it ?
>>
>   Bisected.
> b4eef9b36db461ca44832226fbca614db58c0c33 is the first bad commit
> commit b4eef9b36db461ca44832226fbca614db58c0c33
> Author: Tiejun Chen <tiejun.chen@...el.com>
> Date:   Mon Dec 22 10:32:57 2014 +0100
>
>      kvm: x86: vmx: NULL out hwapic_isr_update() in case of
> !enable_apicv
>
>      In most cases calling hwapic_isr_update(), we always check if
>      kvm_apic_vid_enabled() == 1, but actually,
>      kvm_apic_vid_enabled()
>          -> kvm_x86_ops->vm_has_apicv()
>              -> vmx_vm_has_apicv() or '0' in svm case
>                  -> return enable_apicv && irqchip_in_kernel(kvm)
>
>      So its a little cost to recall vmx_vm_has_apicv() inside
>      hwapic_isr_update(), here just NULL out hwapic_isr_update() in
>      case of !enable_apicv inside hardware_setup() then make all
>      related stuffs follow this. Note we don't check this under that
>      condition of irqchip_in_kernel() since we should make sure
>      definitely any caller don't work  without in-kernel irqchip.
>
>      Signed-off-by: Tiejun Chen <tiejun.chen@...el.com>
>      Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
>
>   I have reverted this from -rc2 (big offsets, 209 and 357 lines) and
> everything is working again.
>

Did you try Linux 4.0-rc3? That includes one relevant fix,

KVM: SVM: fix interrupt injection (apic->isr_count always 0)

Thanks
Tiejun
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