linux-kernel - [PATCH 3/3] KVM: x86/mmu: Extract zapping of rmaps for gfn range to separate helper

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Message-Id: <20211022010005.1454978-4-seanjc@google.com>
Date:   Thu, 21 Oct 2021 18:00:05 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Maxim Levitsky <mlevitsk@...hat.com>,
        "Maciej S . Szmigiero" <maciej.szmigiero@...cle.com>,
        Ben Gardon <bgardon@...gle.com>
Subject: [PATCH 3/3] KVM: x86/mmu: Extract zapping of rmaps for gfn range to
 separate helper

Extract the zapping of rmaps, a.k.a. legacy MMU, for a gfn range to a
separate helper to clean up the unholy mess that kvm_zap_gfn_range() has
become.  In addition to deep nesting, the rmaps zapping spreads out the
declaration of several variables and is generally a mess.  Clean up the
mess now so that future work to improve the memslots implementation
doesn't need to deal with it.

Cc: Maciej S. Szmigiero <maciej.szmigiero@...cle.com>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/mmu/mmu.c | 52 ++++++++++++++++++++++++------------------
 1 file changed, 30 insertions(+), 22 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index e8b8a665e2e9..182d35a216d4 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5667,40 +5667,48 @@ void kvm_mmu_uninit_vm(struct kvm *kvm)
 	kvm_mmu_uninit_tdp_mmu(kvm);
 }
 
+static bool __kvm_zap_rmaps(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end)
+{
+	const struct kvm_memory_slot *memslot;
+	struct kvm_memslots *slots;
+	bool flush = false;
+	gfn_t start, end;
+	int i;
+
+	if (!kvm_memslots_have_rmaps(kvm))
+		return flush;
+
+	for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
+		slots = __kvm_memslots(kvm, i);
+		kvm_for_each_memslot(memslot, slots) {
+			start = max(gfn_start, memslot->base_gfn);
+			end = min(gfn_end, memslot->base_gfn + memslot->npages);
+			if (start >= end)
+				continue;
+
+			flush = slot_handle_level_range(kvm, memslot, kvm_zap_rmapp,
+							PG_LEVEL_4K, KVM_MAX_HUGEPAGE_LEVEL,
+							start, end - 1, true, flush);
+		}
+	}
+
+	return flush;
+}
+
 /*
  * Invalidate (zap) SPTEs that cover GFNs from gfn_start and up to gfn_end
  * (not including it)
  */
 void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end)
 {
-	struct kvm_memslots *slots;
-	struct kvm_memory_slot *memslot;
+	bool flush;
 	int i;
-	bool flush = false;
 
 	write_lock(&kvm->mmu_lock);
 
 	kvm_inc_notifier_count(kvm, gfn_start, gfn_end);
 
-	if (kvm_memslots_have_rmaps(kvm)) {
-		for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
-			slots = __kvm_memslots(kvm, i);
-			kvm_for_each_memslot(memslot, slots) {
-				gfn_t start, end;
-
-				start = max(gfn_start, memslot->base_gfn);
-				end = min(gfn_end, memslot->base_gfn + memslot->npages);
-				if (start >= end)
-					continue;
-
-				flush = slot_handle_level_range(kvm,
-						(const struct kvm_memory_slot *) memslot,
-						kvm_zap_rmapp, PG_LEVEL_4K,
-						KVM_MAX_HUGEPAGE_LEVEL, start,
-						end - 1, true, flush);
-			}
-		}
-	}
+	flush = __kvm_zap_rmaps(kvm, gfn_start, gfn_end);
 
 	if (is_tdp_mmu_enabled(kvm)) {
 		for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++)
-- 
2.33.0.1079.g6e70778dc9-goog