From: Ben Gardon <bgardon@google.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: Paolo Bonzini <pbonzini@redhat.com>, Peter Xu <peterx@redhat.com>,
Sean Christopherson <seanjc@google.com>,
David Matlack <dmatlack@google.com>,
Vipin Sharma <vipinsh@google.com>,
Ricardo Koller <ricarkol@google.com>,
Ben Gardon <bgardon@google.com>
Subject: [PATCH 11/21] KVM: x86/MMU: Cleanup shrinker interface with Shadow MMU
Date: Thu, 2 Feb 2023 18:27:59 +0000 [thread overview]
Message-ID: <20230202182809.1929122-12-bgardon@google.com> (raw)
In-Reply-To: <20230202182809.1929122-1-bgardon@google.com>
The MMU shrinker currently only operates on the Shadow MMU, but having
the entire implemenatation in shadow_mmu.c is awkward since much of the
function isn't Shadow MMU specific. There has also been talk of changing
the target of the shrinker to the MMU caches rather than already allocated
page tables. As a result, it makes sense to move some of the implementation
back to mmu.c.
No functional change intended.
Signed-off-by: Ben Gardon <bgardon@google.com>
---
arch/x86/kvm/mmu/mmu.c | 43 ++++++++++++++++++++++++
arch/x86/kvm/mmu/shadow_mmu.c | 62 ++++++++---------------------------
arch/x86/kvm/mmu/shadow_mmu.h | 3 +-
3 files changed, 58 insertions(+), 50 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index cef481a17a519..3ea54b08239aa 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -3145,6 +3145,49 @@ static unsigned long mmu_shrink_count(struct shrinker *shrink,
return percpu_counter_read_positive(&kvm_total_used_mmu_pages);
}
+unsigned long mmu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
+{
+ struct kvm *kvm;
+ int nr_to_scan = sc->nr_to_scan;
+ unsigned long freed = 0;
+
+ mutex_lock(&kvm_lock);
+
+ list_for_each_entry(kvm, &vm_list, vm_list) {
+ /*
+ * Never scan more than sc->nr_to_scan VM instances.
+ * Will not hit this condition practically since we do not try
+ * to shrink more than one VM and it is very unlikely to see
+ * !n_used_mmu_pages so many times.
+ */
+ if (!nr_to_scan--)
+ break;
+
+ /*
+ * n_used_mmu_pages is accessed without holding kvm->mmu_lock
+ * here. We may skip a VM instance errorneosly, but we do not
+ * want to shrink a VM that only started to populate its MMU
+ * anyway.
+ */
+ if (!kvm->arch.n_used_mmu_pages &&
+ !kvm_shadow_mmu_has_zapped_obsolete_pages(kvm))
+ continue;
+
+ freed = kvm_shadow_mmu_shrink_scan(kvm, sc->nr_to_scan);
+
+ /*
+ * unfair on small ones
+ * per-vm shrinkers cry out
+ * sadness comes quickly
+ */
+ list_move_tail(&kvm->vm_list, &vm_list);
+ break;
+ }
+
+ mutex_unlock(&kvm_lock);
+ return freed;
+}
+
static struct shrinker mmu_shrinker = {
.count_objects = mmu_shrink_count,
.scan_objects = mmu_shrink_scan,
diff --git a/arch/x86/kvm/mmu/shadow_mmu.c b/arch/x86/kvm/mmu/shadow_mmu.c
index 1be680bce15a6..76c50aca3c487 100644
--- a/arch/x86/kvm/mmu/shadow_mmu.c
+++ b/arch/x86/kvm/mmu/shadow_mmu.c
@@ -3160,7 +3160,7 @@ void kvm_zap_obsolete_pages(struct kvm *kvm)
kvm_mmu_commit_zap_page(kvm, &kvm->arch.zapped_obsolete_pages);
}
-static bool kvm_has_zapped_obsolete_pages(struct kvm *kvm)
+bool kvm_shadow_mmu_has_zapped_obsolete_pages(struct kvm *kvm)
{
return unlikely(!list_empty_careful(&kvm->arch.zapped_obsolete_pages));
}
@@ -3429,60 +3429,24 @@ void kvm_rmap_zap_collapsible_sptes(struct kvm *kvm,
kvm_arch_flush_remote_tlbs_memslot(kvm, slot);
}
-unsigned long mmu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
+unsigned long kvm_shadow_mmu_shrink_scan(struct kvm *kvm, int pages_to_free)
{
- struct kvm *kvm;
- int nr_to_scan = sc->nr_to_scan;
unsigned long freed = 0;
+ int idx;
- mutex_lock(&kvm_lock);
-
- list_for_each_entry(kvm, &vm_list, vm_list) {
- int idx;
- LIST_HEAD(invalid_list);
-
- /*
- * Never scan more than sc->nr_to_scan VM instances.
- * Will not hit this condition practically since we do not try
- * to shrink more than one VM and it is very unlikely to see
- * !n_used_mmu_pages so many times.
- */
- if (!nr_to_scan--)
- break;
- /*
- * n_used_mmu_pages is accessed without holding kvm->mmu_lock
- * here. We may skip a VM instance errorneosly, but we do not
- * want to shrink a VM that only started to populate its MMU
- * anyway.
- */
- if (!kvm->arch.n_used_mmu_pages &&
- !kvm_has_zapped_obsolete_pages(kvm))
- continue;
-
- idx = srcu_read_lock(&kvm->srcu);
- write_lock(&kvm->mmu_lock);
-
- if (kvm_has_zapped_obsolete_pages(kvm)) {
- kvm_mmu_commit_zap_page(kvm,
- &kvm->arch.zapped_obsolete_pages);
- goto unlock;
- }
+ idx = srcu_read_lock(&kvm->srcu);
+ write_lock(&kvm->mmu_lock);
- freed = kvm_mmu_zap_oldest_mmu_pages(kvm, sc->nr_to_scan);
+ if (kvm_shadow_mmu_has_zapped_obsolete_pages(kvm)) {
+ kvm_mmu_commit_zap_page(kvm, &kvm->arch.zapped_obsolete_pages);
+ goto out;
+ }
-unlock:
- write_unlock(&kvm->mmu_lock);
- srcu_read_unlock(&kvm->srcu, idx);
+ freed = kvm_mmu_zap_oldest_mmu_pages(kvm, pages_to_free);
- /*
- * unfair on small ones
- * per-vm shrinkers cry out
- * sadness comes quickly
- */
- list_move_tail(&kvm->vm_list, &vm_list);
- break;
- }
+out:
+ write_unlock(&kvm->mmu_lock);
+ srcu_read_unlock(&kvm->srcu, idx);
- mutex_unlock(&kvm_lock);
return freed;
}
diff --git a/arch/x86/kvm/mmu/shadow_mmu.h b/arch/x86/kvm/mmu/shadow_mmu.h
index 9f16c4782bfbf..9e27d03fbe368 100644
--- a/arch/x86/kvm/mmu/shadow_mmu.h
+++ b/arch/x86/kvm/mmu/shadow_mmu.h
@@ -112,7 +112,8 @@ void kvm_shadow_mmu_try_split_huge_pages(struct kvm *kvm,
void kvm_rmap_zap_collapsible_sptes(struct kvm *kvm,
const struct kvm_memory_slot *slot);
-unsigned long mmu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc);
+bool kvm_shadow_mmu_has_zapped_obsolete_pages(struct kvm *kvm);
+unsigned long kvm_shadow_mmu_shrink_scan(struct kvm *kvm, int pages_to_free);
/* Exports from paging_tmpl.h */
gpa_t paging32_gva_to_gpa(struct kvm_vcpu *vcpu, struct kvm_mmu *mmu,
--
2.39.1.519.gcb327c4b5f-goog
next prev parent reply other threads:[~2023-02-02 18:30 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-02 18:27 [PATCH 00/21] KVM: x86/MMU: Formalize the Shadow MMU Ben Gardon
2023-02-02 18:27 ` [PATCH 01/21] KVM: x86/mmu: Rename slot rmap walkers to add clarity and clean up code Ben Gardon
2023-02-02 18:27 ` [PATCH 02/21] KVM: x86/mmu: Replace comment with an actual lockdep assertion on mmu_lock Ben Gardon
2023-02-02 18:27 ` [PATCH 03/21] KVM: x86/mmu: Clean up mmu.c functions that put return type on separate line Ben Gardon
2023-02-02 18:27 ` [PATCH 04/21] KVM: x86/MMU: Add shadow_mmu.(c|h) Ben Gardon
2023-02-02 18:27 ` [PATCH 05/21] KVM: x86/MMU: Expose functions for the Shadow MMU Ben Gardon
2023-02-02 18:27 ` [PATCH 06/21] KVM: x86/mmu: Get rid of is_cpuid_PSE36() Ben Gardon
2023-03-20 18:51 ` Sean Christopherson
2023-02-02 18:27 ` [PATCH 07/21] KVM: x86/MMU: Move the Shadow MMU implementation to shadow_mmu.c Ben Gardon
2023-02-02 18:27 ` [PATCH 08/21] KVM: x86/MMU: Expose functions for paging_tmpl.h Ben Gardon
2023-02-02 18:27 ` [PATCH 09/21] KVM: x86/MMU: Move paging_tmpl.h includes to shadow_mmu.c Ben Gardon
2023-03-20 18:41 ` Sean Christopherson
2023-03-21 18:43 ` Ben Gardon
2023-02-02 18:27 ` [PATCH 10/21] KVM: x86/MMU: Clean up Shadow MMU exports Ben Gardon
2023-02-02 18:27 ` Ben Gardon [this message]
2023-02-04 13:52 ` [PATCH 11/21] KVM: x86/MMU: Cleanup shrinker interface with Shadow MMU kernel test robot
2023-02-04 19:10 ` kernel test robot
2023-02-02 18:28 ` [PATCH 12/21] KVM: x86/MMU: Clean up naming of exported Shadow MMU functions Ben Gardon
2023-02-02 18:28 ` [PATCH 13/21] KVM: x86/MMU: Fix naming on prepare / commit zap page functions Ben Gardon
2023-02-02 18:28 ` [PATCH 14/21] KVM: x86/MMU: Factor Shadow MMU wrprot / clear dirty ops out of mmu.c Ben Gardon
2023-02-02 18:28 ` [PATCH 15/21] KVM: x86/MMU: Remove unneeded exports from shadow_mmu.c Ben Gardon
2023-02-04 14:44 ` kernel test robot
2023-02-02 18:28 ` [PATCH 16/21] KVM: x86/MMU: Wrap uses of kvm_handle_gfn_range in mmu.c Ben Gardon
2023-02-02 18:28 ` [PATCH 17/21] KVM: x86/MMU: Add kvm_shadow_mmu_ to the last few functions in shadow_mmu.h Ben Gardon
2023-02-02 18:28 ` [PATCH 18/21] KVM: x86/mmu: Move split cache topup functions to shadow_mmu.c Ben Gardon
2023-02-02 18:28 ` [PATCH 19/21] KVM: x86/mmu: Move Shadow MMU part of kvm_mmu_zap_all() to shadow_mmu.h Ben Gardon
2023-02-02 18:28 ` [PATCH 20/21] KVM: x86/mmu: Move Shadow MMU init/teardown to shadow_mmu.c Ben Gardon
2023-02-02 18:28 ` [PATCH 21/21] KVM: x86/mmu: Split out Shadow MMU lockless walk begin/end Ben Gardon
2023-03-20 19:09 ` [PATCH 00/21] KVM: x86/MMU: Formalize the Shadow MMU Sean Christopherson
2023-03-23 23:02 ` Sean Christopherson
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