[PATCH v4 3/4] KVM: x86/mmu: count KVM mmu usage in secondary pagetable stats.

Yosry Ahmed
2022-04-29T20:12:09Z

Count the pages used by KVM mmu on x86 for in secondary pagetable stats.

For the legacy mmu, accounting pagetable stats is combined KVM's
existing for mmu pages in newly introduced kvm_[un]account_mmu_page()
helpers.

For tdp mmu, introduce new tdp_[un]account_mmu_page() helpers. That
combines accounting pagetable stats with the tdp_mmu_pages counter
accounting.

tdp_mmu_pages counter introduced in this series [1]. This patch was
rebased on top of the first two patches in that series.

[1]https://lore.kernel.org/lkml/20220401063636.2414200-1-mizhang@google.com/

Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
---
arch/x86/kvm/mmu/mmu.c | 16 ++++++++++++++--
arch/x86/kvm/mmu/tdp_mmu.c | 16 ++++++++++++++--
2 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 78d8e1d8fb99..e5b0e826445d 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -1679,6 +1679,18 @@ static inline void kvm_mod_used_mmu_pages(struct kvm *kvm, long nr)
percpu_counter_add(&kvm_total_used_mmu_pages, nr);
}

+static void kvm_account_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp)
+{
+ kvm_mod_used_mmu_pages(kvm, +1);
+ kvm_account_pgtable_pages((void *)sp->spt, +1);
+}
+
+static void kvm_unaccount_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp)
+{
+ kvm_mod_used_mmu_pages(kvm, -1);
+ kvm_account_pgtable_pages((void *)sp->spt, -1);
+}
+
static void kvm_mmu_free_page(struct kvm_mmu_page *sp)
{
MMU_WARN_ON(!is_empty_shadow_page(sp->spt));
@@ -1734,7 +1746,7 @@ static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu, int direct
*/
sp->mmu_valid_gen = vcpu->kvm->arch.mmu_valid_gen;
list_add(&sp->link, &vcpu->kvm->arch.active_mmu_pages);
- kvm_mod_used_mmu_pages(vcpu->kvm, +1);
+ kvm_account_mmu_page(vcpu->kvm, sp);
return sp;
}

@@ -2363,7 +2375,7 @@ static bool __kvm_mmu_prepare_zap_page(struct kvm *kvm,
list_add(&sp->link, invalid_list);
else
list_move(&sp->link, invalid_list);
- kvm_mod_used_mmu_pages(kvm, -1);
+ kvm_unaccount_mmu_page(kvm, sp);
} else {
/*
* Remove the active root from the active page list, the root
diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c
index 3456277ade18..6295c4da5dee 100644
--- a/arch/x86/kvm/mmu/tdp_mmu.c
+++ b/arch/x86/kvm/mmu/tdp_mmu.c
@@ -371,6 +371,18 @@ static void handle_changed_spte_dirty_log(struct kvm *kvm, int as_id, gfn_t gfn,
}
}

+static void tdp_account_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp)
+{
+ atomic64_inc(&kvm->arch.tdp_mmu_pages);
+ kvm_account_pgtable_pages((void *)sp->spt, +1);
+}
+
+static void tdp_unaccount_mmu_page(struct kvm *kvm, struct kvm_mmu_page *sp)
+{
+ atomic64_dec(&kvm->arch.tdp_mmu_pages);
+ kvm_account_pgtable_pages((void *)sp->spt, -1);
+}
+
/**
* tdp_mmu_unlink_sp() - Remove a shadow page from the list of used pages
*
@@ -383,7 +395,7 @@ static void handle_changed_spte_dirty_log(struct kvm *kvm, int as_id, gfn_t gfn,
static void tdp_mmu_unlink_sp(struct kvm *kvm, struct kvm_mmu_page *sp,
bool shared)
{
- atomic64_dec(&kvm->arch.tdp_mmu_pages);
+ tdp_unaccount_mmu_page(kvm, sp);

if (!sp->lpage_disallowed)
return;
@@ -1121,7 +1133,7 @@ static int tdp_mmu_link_sp(struct kvm *kvm, struct tdp_iter *iter,
tdp_mmu_set_spte(kvm, iter, spte);
}

- atomic64_inc(&kvm->arch.tdp_mmu_pages);
+ tdp_account_mmu_page(kvm, sp);

return 0;
}
--
2.36.0.464.gb9c8b46e94-goog