KVM: MMU: Mark sp mmio cached when creating mmio spte

This will be used not to zap unrelated mmu pages when creating/moving
a memory slot later.

Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
Signed-off-by: Gleb Natapov <gleb@redhat.com>

arch/x86/include/asm/kvm_host.h

@@ -230,6 +230,7 @@ struct kvm_mmu_page {
 #endif
 
 	int write_flooding_count;
+	bool mmio_cached;
 };
 
 struct kvm_pio_request {

arch/x86/kvm/mmu.c

@@ -199,8 +199,11 @@ EXPORT_SYMBOL_GPL(kvm_mmu_set_mmio_spte_mask);
 
 static void mark_mmio_spte(u64 *sptep, u64 gfn, unsigned access)
 {
+	struct kvm_mmu_page *sp =  page_header(__pa(sptep));
+
 	access &= ACC_WRITE_MASK | ACC_USER_MASK;
 
+	sp->mmio_cached = true;
 	trace_mark_mmio_spte(sptep, gfn, access);
 	mmu_spte_set(sptep, shadow_mmio_mask | access | gfn << PAGE_SHIFT);
 }