Re: kvm-60: kexec in guest crashes the host

Avi Kivity
2008-02-27T14:02:53Z

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Avi Kivity wrote:
> Dan Aloni wrote:
>
>> On Wed, Feb 20, 2008 at 11:09:44AM +0200, Avi Kivity wrote:
>>
>>
>>> Dan Aloni wrote:
>>>
>>>
>>>> It happens at 100% of the times I invoke kexec.
>>>>
>>>>
>>>>
>>>>
>>> Can you provide a commandline which triggers this? I'm completely
>>> ignorant wrt kexec.
>>>
>>>
>> I managed to verify that this problem can be reproduced with the
>> 2.6.16.60 tree.
>>
>> Also, it's worth to note that with '-no-kvm' the kexec procedure works
>> successfully and the second kernel executes.
>>
>> Please use the .config that that I attached to this mail, and also apply
>> the patch I supplied (it fixes a build problem that 2.6.16 has with the
>> newer binutils versions and x86_64). I use gcc-4.1.2 to build the kernel.
>>
>> Once you have the bzImage of that guest kernel, use a root filesystem
>> and boot it straight into /bin/bash.
>>
>> Now, assuming that your guest rootfs has kexec-utils package installed,
>> do the following:
>>
>> mount -t proc proc /proc
>> kexec -l bzImage --command-line='ro root=/dev/hda1 init=/bin/bash'
>> kexec -e
>>
>> BTW, if you use the serial console with the '-nographic' switch, then
>> you might want to use kexec a little differently:
>>
>> kexec -l bzImage --command-line='ro root=/dev/hda1 init=/bin/bash console=ttyS0,115200' --serial=ttyS0 --serial-baud=115200
>>
>>
>
> I managed to reproduce it (FC6 kernel kexecing itself). It is Intel
> specific.
>
>

The attached patch fixes the problem for me.

--
error compiling committee.c: too many arguments to function

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diff --git a/kernel/vmx.c b/kernel/vmx.c
index 7ce02d2..ccc8174 100644
--- a/kernel/vmx.c
+++ b/kernel/vmx.c
@@ -1356,6 +1356,7 @@ static void vmx_set_efer(struct kvm_vcpu *vcpu, u64 efer)

msr->data = efer & ~EFER_LME;
}
+ vmx_load_host_state(vmx);
setup_msrs(vmx);
}

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