Re: [PATCH] KVM: Fix mmu_reload() clash with nested vmx event injection

[Marcelo Tosatti <mtosatti@redhat.com>]

On Mon, May 14, 2012 at 06:07:56PM +0300, Avi Kivity wrote:
> Currently the inject_pending_event() call during guest entry happens after
> kvm_mmu_reload().  This is for historical reasons - we used to
> inject_pending_event() in atomic context, while kvm_mmu_reload() needs task
> context.
> 
> A problem is that nested vmx can cause the mmu context to be reset, if event
> injection is intercepted and causes a #VMEXIT instead (the #VMEXIT resets
> CR0/CR3/CR4).  If this happens, we end up with invalid root_hpa, and since
> kvm_mmu_reload() has already run, no one will fix it and we end up entering
> the guest this way.
> 
> Fix by reordering event injection to be before kvm_mmu_reload().  Use
> ->cancel_injection() to undo if kvm_mmu_reload() fails.
> 
> https://bugzilla.kernel.org/show_bug.cgi?id=42980
> 
> Reported-by: Luke-Jr <luke-jr+linuxbugs@utopios.org>
> Signed-off-by: Avi Kivity <avi@redhat.com>
> ---
>  arch/x86/kvm/x86.c |   10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)

Applied, thanks.