Re: BUG with Win7 and user-return-notifier

[Jan Kiszka <jan.kiszka@siemens.com>]

Jan Kiszka wrote:
> Avi Kivity wrote:
>> On 10/28/2009 10:40 PM, Jan Kiszka wrote:
>>>> [you can get longer, more detailed traces by using
>>>> /sys/kernel/debug/tracing/trace instead of dmesg]
>>>>
>>>> Oct 28 14:29:56 mchn012c kernel: qemu-sys-7200    0...1. 676996395us :
>>>> kvm_msr: msr_read c0000080 = 0x500
>>>> Oct 28 14:29:56 mchn012c kernel: qemu-sys-7200    0...1. 676996403us :
>>>> kvm_msr: msr_write c0000080 = 0xd01
>>>>
>>>> So Windows is setting EFER.SCE and EFER.NX while in long mode -
>>>> perfectly reasonable.  Can you rerun with the attached debug patch?
>>>>
>>>>      
>>> Log attached.
>>>    
>> So the last bits are:
>>
>> Oct 28 21:26:41 mchn012c kernel: update_transition_efer: efer_offset 4
>> efer d01
>> Oct 28 21:26:41 mchn012c kernel: update_transition_efer: ignoring all bits
>> Oct 28 21:26:41 mchn012c kernel: setup_msrs: marking efer for no reload
>>
>> We're not reloading efer (correctly, as guest efer == host efer), yet
>> vmx_save_host_state() fails while loading efer.  I've looked at
>> move_msr_up() (which is used by setup_msrs() to partition the msr space
>> into reloaded and non-reloaded msrs), and it seems correct.
>>
>> Can you see any way where update_transition_efer() returns false, yet
>> efer turns up in the first save_nmsrs entries of vmx->guest_msrs?
>>
> 
> Question: When a VCPU migrates, what syncs the shared_msrs per-cpu vars
> before or after that, or why is this no problem?
> 
> I'm currently following the theory that guest_msrs contains some
> non-EFER entry with 0 value, but shared_msrs has a different index in
> the slot passed to kvm_set_shared_msr.
> 

OK, EFER is a globally shared msr. But there still needs to be a
consensus on the slot id used for guest_msrs and
shared_msrs_global.msrs, right? move_msr_up works per-vcpu and is
obviously decoupled...

Jan

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