[PATCH v4 18/20] KVM: x86/mmu: Refactor drop_large_spte()

[David Matlack]

drop_large_spte() drops a large SPTE if it exists and then flushes TLBs.
Its helper function, __drop_large_spte(), does the drop without the
flush.

In preparation for eager page splitting, which will need to sometimes
flush when dropping large SPTEs (and sometimes not), push the flushing
logic down into __drop_large_spte() and add a bool parameter to control
it.

No functional change intended.

Reviewed-by: Peter Xu <peterx at redhat.com>
Signed-off-by: David Matlack <dmatlack at google.com>
---
 arch/x86/kvm/mmu/mmu.c | 29 +++++++++++++++--------------
 1 file changed, 15 insertions(+), 14 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 479c581e8a96..a5961c17eb36 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1183,28 +1183,29 @@ static void drop_spte(struct kvm *kvm, u64 *sptep)
 		rmap_remove(kvm, sptep);
 }
 
-
-static bool __drop_large_spte(struct kvm *kvm, u64 *sptep)
+static void __drop_large_spte(struct kvm *kvm, u64 *sptep, bool flush)
 {
-	if (is_large_pte(*sptep)) {
-		WARN_ON(sptep_to_sp(sptep)->role.level == PG_LEVEL_4K);
-		drop_spte(kvm, sptep);
-		return true;
-	}
+	struct kvm_mmu_page *sp;
 
-	return false;
-}
+	if (!is_large_pte(*sptep))
+		return;
 
-static void drop_large_spte(struct kvm_vcpu *vcpu, u64 *sptep)
-{
-	if (__drop_large_spte(vcpu->kvm, sptep)) {
-		struct kvm_mmu_page *sp = sptep_to_sp(sptep);
+	sp = sptep_to_sp(sptep);
+	WARN_ON(sp->role.level == PG_LEVEL_4K);
 
-		kvm_flush_remote_tlbs_with_address(vcpu->kvm, sp->gfn,
+	drop_spte(kvm, sptep);
+
+	if (flush) {
+		kvm_flush_remote_tlbs_with_address(kvm, sp->gfn,
 			KVM_PAGES_PER_HPAGE(sp->role.level));
 	}
 }
 
+static void drop_large_spte(struct kvm_vcpu *vcpu, u64 *sptep)
+{
+	return __drop_large_spte(vcpu->kvm, sptep, true);
+}
+
 /*
  * Write-protect on the specified @sptep, @pt_protect indicates whether
  * spte write-protection is caused by protecting shadow page table.
-- 
2.36.0.rc2.479.g8af0fa9b8e-goog