KVM: MMU: unify slots_lock usage

Unify slots_lock acquision around vcpu_run(). This is simpler and less
error-prone.

Also fix some callsites that were not grabbing the lock properly.

[avi: drop slots_lock while in guest mode to avoid holding the lock
      for indefinite periods]

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

diff --cc arch/x86/kvm/mmu.c
Simple merge

diff --cc arch/x86/kvm/paging_tmpl.h
Simple merge

diff --cc arch/x86/kvm/vmx.c
Simple merge

diff --cc arch/x86/kvm/x86.c
Simple merge

diff --cc include/asm-x86/kvm_host.h
Simple merge