Re: [PATCH] call kvm_cpu_synchronize_state() on target vcpu

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

Gleb Natapov wrote:
> On Wed, Sep 09, 2009 at 05:57:40PM +0200, Jan Kiszka wrote:
>> Gleb Natapov wrote:
>>> On Wed, Sep 09, 2009 at 05:47:13PM +0200, Jan Kiszka wrote:
>>>> Gleb Natapov wrote:
>>>>> regs_modified logic doesn't work if io thread calls
>>>>> kvm_cpu_synchronize_state() since kvm_arch_get_registers()
>>>>> returns only after vcpu thread is back to kernel. Setting
>>>>> regs_modified to 1 at this stage causes loading of wrong vcpu
>>>>> state on the next vcpu_run().
>>>> We need this upstream too, right? Could you file the corresponding patch?
>>>>
>>> Upstream is single threaded. It shouldn't suffer from this bug.
>> Not if you enable iothread support (though I don't remember if that
> It can't work with kvm since all vcpu ioctls are called on the thread
> that issues them.

Yeah, I just recalled all that on_vcpu fuzz and that upstream is still
horribly broken /wrt iothread+kvm. But once that is fixed, we also need
this fix here.

> 
>> works now for kvm) + you are also touching shared code here. So qemu-kvm
>> would benefit from keeping the diff small.
>>
> The patch doesn't touch shared code. (it is almost impossible to tell
> what code is shared and what's not nowadays)

cpu_dump_state() is definitely shared.

Jan

-- 
Siemens AG, Corporate Technology, CT SE 2
Corporate Competence Center Embedded Linux