linux-kernel - [PATCH v3 17/31] KVM: x86/mmu: Fold rmap_recycle into rmap

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Date:   Fri, 24 Sep 2021 12:31:38 -0400
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     dmatlack@...gle.com, seanjc@...gle.com
Subject: [PATCH v3 17/31] KVM: x86/mmu: Fold rmap_recycle into rmap_add

From: David Matlack <dmatlack@...gle.com>

Consolidate rmap_recycle and rmap_add into a single function since they
are only ever called together (and only from one place). This has a nice
side effect of eliminating an extra kvm_vcpu_gfn_to_memslot(). In
addition it makes mmu_set_spte(), which is a very long function, a
little shorter.

No functional change intended.

Signed-off-by: David Matlack <dmatlack@...gle.com>
Message-Id: <20210813203504.2742757-3-dmatlack@...gle.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kvm/mmu/mmu.c | 40 ++++++++++++++--------------------------
 1 file changed, 14 insertions(+), 26 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 2ddbabad5bd2..8b6dc276935f 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1071,20 +1071,6 @@ static bool rmap_can_add(struct kvm_vcpu *vcpu)
 	return kvm_mmu_memory_cache_nr_free_objects(mc);
 }
 
-static int rmap_add(struct kvm_vcpu *vcpu, u64 *spte, gfn_t gfn)
-{
-	struct kvm_memory_slot *slot;
-	struct kvm_mmu_page *sp;
-	struct kvm_rmap_head *rmap_head;
-
-	sp = sptep_to_sp(spte);
-	kvm_mmu_page_set_gfn(sp, spte - sp->spt, gfn);
-	slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
-	rmap_head = gfn_to_rmap(gfn, sp->role.level, slot);
-	return pte_list_add(vcpu, spte, rmap_head);
-}
-
-
 static void rmap_remove(struct kvm *kvm, u64 *spte)
 {
 	struct kvm_memslots *slots;
@@ -1097,9 +1083,9 @@ static void rmap_remove(struct kvm *kvm, u64 *spte)
 	gfn = kvm_mmu_page_get_gfn(sp, spte - sp->spt);
 
 	/*
-	 * Unlike rmap_add and rmap_recycle, rmap_remove does not run in the
-	 * context of a vCPU so have to determine which memslots to use based
-	 * on context information in sp->role.
+	 * Unlike rmap_add, rmap_remove does not run in the context of a vCPU
+	 * so we have to determine which memslots to use based on context
+	 * information in sp->role.
 	 */
 	slots = kvm_memslots_for_spte_role(kvm, sp->role);
 
@@ -1639,19 +1625,24 @@ static bool kvm_test_age_rmapp(struct kvm *kvm, struct kvm_rmap_head *rmap_head,
 
 #define RMAP_RECYCLE_THRESHOLD 1000
 
-static void rmap_recycle(struct kvm_vcpu *vcpu, u64 *spte, gfn_t gfn)
+static void rmap_add(struct kvm_vcpu *vcpu, u64 *spte, gfn_t gfn)
 {
 	struct kvm_memory_slot *slot;
-	struct kvm_rmap_head *rmap_head;
 	struct kvm_mmu_page *sp;
+	struct kvm_rmap_head *rmap_head;
+	int rmap_count;
 
 	sp = sptep_to_sp(spte);
+	kvm_mmu_page_set_gfn(sp, spte - sp->spt, gfn);
 	slot = kvm_vcpu_gfn_to_memslot(vcpu, gfn);
 	rmap_head = gfn_to_rmap(gfn, sp->role.level, slot);
+	rmap_count = pte_list_add(vcpu, spte, rmap_head);
 
-	kvm_unmap_rmapp(vcpu->kvm, rmap_head, NULL, gfn, sp->role.level, __pte(0));
-	kvm_flush_remote_tlbs_with_address(vcpu->kvm, sp->gfn,
-			KVM_PAGES_PER_HPAGE(sp->role.level));
+	if (rmap_count > RMAP_RECYCLE_THRESHOLD) {
+		kvm_unmap_rmapp(vcpu->kvm, rmap_head, NULL, gfn, sp->role.level, __pte(0));
+		kvm_flush_remote_tlbs_with_address(
+				vcpu->kvm, sp->gfn, KVM_PAGES_PER_HPAGE(sp->role.level));
+	}
 }
 
 bool kvm_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
@@ -2713,7 +2704,6 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
 			bool host_writable)
 {
 	int was_rmapped = 0;
-	int rmap_count;
 	int set_spte_ret;
 	int ret = RET_PF_FIXED;
 	bool flush = false;
@@ -2772,9 +2762,7 @@ static int mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
 
 	if (!was_rmapped) {
 		kvm_update_page_stats(vcpu->kvm, level, 1);
-		rmap_count = rmap_add(vcpu, sptep, gfn);
-		if (rmap_count > RMAP_RECYCLE_THRESHOLD)
-			rmap_recycle(vcpu, sptep, gfn);
+		rmap_add(vcpu, sptep, gfn);
 	}
 
 	return ret;
-- 
2.27.0