Date:   Mon,  6 Mar 2023 14:41:15 -0800
In-Reply-To: <20230306224127.1689967-1-vipinsh@google.com>
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Message-ID: <20230306224127.1689967-7-vipinsh@google.com>
Subject: [Patch v4 06/18] KVM: x86/mmu: Shrink split_shadow_page_cache via MMU shrinker
From:   Vipin Sharma <vipinsh@google.com>
To:     seanjc@google.com, pbonzini@redhat.com, bgardon@google.com,
        dmatlack@google.com
Cc:     jmattson@google.com, mizhang@google.com, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org, Vipin Sharma <vipinsh@google.com>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Use MMU shrinker to free unused pages in split_shadow_page_cache.
Refactor the code and make common function to try emptying the page cache.

Signed-off-by: Vipin Sharma <vipinsh@google.com>
---
 arch/x86/kvm/mmu/mmu.c | 34 +++++++++++++++++++++-------------
 1 file changed, 21 insertions(+), 13 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 0ebb8a2eaf47..73a0ac9c11ce 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -6696,13 +6696,24 @@ void kvm_mmu_invalidate_mmio_sptes(struct kvm *kvm, u64 gen)
 	}
 }
 
+static int mmu_memory_cache_try_empty(struct kvm_mmu_memory_cache *cache,
+				      struct mutex *cache_lock)
+{
+	int freed = 0;
+
+	if (mutex_trylock(cache_lock)) {
+		freed = cache->nobjs;
+		kvm_mmu_empty_memory_cache(cache);
+		mutex_unlock(cache_lock);
+	}
+	return freed;
+}
+
 static unsigned long mmu_shrink_scan(struct shrinker *shrink,
 				     struct shrink_control *sc)
 {
 	struct kvm *kvm, *next_kvm, *first_kvm = NULL;
-	struct kvm_mmu_memory_cache *cache;
 	unsigned long i, freed = 0;
-	struct mutex *cache_lock;
 	struct kvm_vcpu *vcpu;
 
 	mutex_lock(&kvm_lock);
@@ -6716,18 +6727,15 @@ static unsigned long mmu_shrink_scan(struct shrinker *shrink,
 		list_move_tail(&kvm->vm_list, &vm_list);
 
 		kvm_for_each_vcpu(i, vcpu, kvm) {
-			cache = &vcpu->arch.mmu_shadow_page_cache;
-			cache_lock = &vcpu->arch.mmu_shadow_page_cache_lock;
-			if (mutex_trylock(cache_lock)) {
-				if (cache->nobjs) {
-					freed += cache->nobjs;
-					kvm_mmu_empty_memory_cache(cache);
-				}
-				mutex_unlock(cache_lock);
-				if (freed >= sc->nr_to_scan)
-					goto out;
-			}
+			freed += mmu_memory_cache_try_empty(&vcpu->arch.mmu_shadow_page_cache,
+							    &vcpu->arch.mmu_shadow_page_cache_lock);
+			if (freed >= sc->nr_to_scan)
+				goto out;
 		}
+		freed += mmu_memory_cache_try_empty(&kvm->arch.split_shadow_page_cache,
+						    &kvm->slots_lock);
+		if (freed >= sc->nr_to_scan)
+			goto out;
 	}
 out:
 	mutex_unlock(&kvm_lock);
-- 
2.40.0.rc0.216.gc4246ad0f0-goog