KVM: introduce kvm->srcu and convert kvm_set_memory_region to SRCU update

Use two steps for memslot deletion: mark the slot invalid (which stops
instantiation of new shadow pages for that slot, but allows destruction),
then instantiate the new empty slot.

Also simplifies kvm_handle_hva locking.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index 18698799e365..f1cae7d6113d 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1503,7 +1503,11 @@ static void enter_pmode(struct kvm_vcpu *vcpu)
 static gva_t rmode_tss_base(struct kvm *kvm)
 {
         if (!kvm->arch.tss_addr) {
-                gfn_t base_gfn = kvm->memslots->memslots[0].base_gfn +
+                struct kvm_memslots *slots;
+                gfn_t base_gfn;
+
+                slots = rcu_dereference(kvm->memslots);
+                base_gfn = kvm->memslots->memslots[0].base_gfn +
                                  kvm->memslots->memslots[0].npages - 3;
                 return base_gfn << PAGE_SHIFT;
         }