kvm/x86: Fix 'lpages' kvm stat for TDM MMU

Large pages not being created properly may result in increased memory
access time. The 'lpages' kvm stat used to keep track of the current
number of large pages in the system, but with TDP MMU enabled the stat
is not showing the correct number.

This patch extends the lpages counter to cover the TDP case.
Signed-off-by: Md Shahadat Hossain Shahin <shahinmd@amazon.de>
Cc: Bartosz Szczepanek <bsz@amazon.de>
Message-Id: <1619783551459.35424@amazon.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

arch/x86/kvm/mmu/tdp_mmu.c

@@ -444,6 +444,13 @@ static void __handle_changed_spte(struct kvm *kvm, int as_id, gfn_t gfn,
 
 	trace_kvm_tdp_mmu_spte_changed(as_id, gfn, level, old_spte, new_spte);
 
+	if (is_large_pte(old_spte) != is_large_pte(new_spte)) {
+		if (is_large_pte(old_spte))
+			atomic64_sub(1, (atomic64_t*)&kvm->stat.lpages);
+		else
+			atomic64_add(1, (atomic64_t*)&kvm->stat.lpages);
+	}
+
 	/*
 	 * The only times a SPTE should be changed from a non-present to
 	 * non-present state is when an MMIO entry is installed/modified/