[PATCH v7 2/4] KVM: mmu: add a helper to account memory used by KVM MMU.

[Yosry Ahmed <yosryahmed@google.com>]

Add a helper to account pages used by KVM for page tables in memory
secondary pagetable stats. This function will be used by subsequent
patches in different archs.

Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
Acked-by: Marc Zyngier <maz@kernel.org>
---
 include/linux/kvm_host.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index f4519d3689e1..04c7e5f2f727 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -2247,6 +2247,19 @@ static inline void kvm_handle_signal_exit(struct kvm_vcpu *vcpu)
 }
 #endif /* CONFIG_KVM_XFER_TO_GUEST_WORK */
 
+/*
+ * If more than one page is being (un)accounted, @virt must be the address of
+ * the first page of a block of pages what were allocated together (i.e
+ * accounted together).
+ *
+ * kvm_account_pgtable_pages() is thread-safe because mod_lruvec_page_state()
+ * is thread-safe.
+ */
+static inline void kvm_account_pgtable_pages(void *virt, int nr)
+{
+	mod_lruvec_page_state(virt_to_page(virt), NR_SECONDARY_PAGETABLE, nr);
+}
+
 /*
  * This defines how many reserved entries we want to keep before we
  * kick the vcpu to the userspace to avoid dirty ring full.  This
-- 
2.37.1.595.g718a3a8f04-goog