On Thu, Dec 15, 2011 at 11:21:37AM +0800, Liu ping fan wrote:
> On Tue, Dec 13, 2011 at 7:36 PM, Marcelo Tosatti <mtosa...@redhat.com> wrote:
> > On Mon, Dec 12, 2011 at 10:41:23AM +0800, Liu Ping Fan wrote:
> >> From: Liu Ping Fan <pingf...@linux.vnet.ibm.com>
> >>
> >> Currently, vcpu can be destructed only when kvm instance destroyed.
> >> Change this to vcpu's destruction taken when its refcnt is zero,
> >> and then vcpu MUST and CAN be destroyed before kvm's destroy.
> >>
> >> Signed-off-by: Liu Ping Fan <pingf...@linux.vnet.ibm.com>
> >> ---
> >> arch/x86/kvm/i8254.c | 10 ++++--
> >> arch/x86/kvm/i8259.c | 12 +++++--
> >> arch/x86/kvm/mmu.c | 7 ++--
> >> arch/x86/kvm/x86.c | 54 +++++++++++++++++++----------------
> >> include/linux/kvm_host.h | 71
> >> ++++++++++++++++++++++++++++++++++++++++++----
> >> virt/kvm/irq_comm.c | 7 +++-
> >> virt/kvm/kvm_main.c | 62 +++++++++++++++++++++++++++++++++------
> >> 7 files changed, 170 insertions(+), 53 deletions(-)
> >
> > This needs a full audit of paths that access vcpus. See for one example
> > bsp_vcpu pointer.
> >
> Yes, I had missed it and just paid attention to the access path to
> vcpu in kvm_lapic and the path used in async_pf. I will correct it
> later.
> BTW, I want to make it sure that because kvm_lapic will be destroyed
> before vcpu, so it is safe to bypass the access path there, and the
> situation is the same in async_pf for we have called
> kvm_clear_async_pf_completion_queue before zapping vcpu. Am I right?
>
> As to the scene like bsp_vcpu, I think that introducing refcount like
> in V2 can handle it easier. Please help to review these changes in V4
> which I will send a little later.
>
Since bsp_vcpu pointer will never be released or re-assigned introducing
reference count to keep the pointer valid is not necessary. The counter
will never reach 0 and bsp vcpu will never be freed. Just disallow
removal of bsp_vcpu. Or better get rid of bsp_vcpu at all since its only
use is invalid anyway.
--
Gleb.
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