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

[Gleb Natapov <gleb@redhat.com>]

On Wed, Sep 09, 2009 at 06:21:48PM +0200, Jan Kiszka wrote:
> 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.
> 
This will be done as part of transition to on_vcpu() for vcpu ioctls.

> > 
> >> 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.
> 
Ah this one line. Yes it is. But I have not good commit message for this
one liner change for upstream :)

--
			Gleb.