linux-kernel - [PATCH v6 4/4] KVM: arm64/mmu: count KVM s2 mmu usage in secondary pagetable stats

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Message-Id: <20220628220938.3657876-5-yosryahmed@google.com>
Date:   Tue, 28 Jun 2022 22:09:38 +0000
From:   Yosry Ahmed <yosryahmed@...gle.com>
To:     Tejun Heo <tj@...nel.org>, Johannes Weiner <hannes@...xchg.org>,
        Zefan Li <lizefan.x@...edance.com>,
        Marc Zyngier <maz@...nel.org>,
        James Morse <james.morse@....com>,
        Alexandru Elisei <alexandru.elisei@....com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        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>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...nel.org>,
        Roman Gushchin <roman.gushchin@...ux.dev>,
        Shakeel Butt <shakeelb@...gle.com>,
        Oliver Upton <oupton@...gle.com>
Cc:     Huang@...gle.com, Shaoqin <shaoqin.huang@...el.com>,
        cgroups@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, kvmarm@...ts.cs.columbia.edu,
        kvm@...r.kernel.org, linux-mm@...ck.org,
        Yosry Ahmed <yosryahmed@...gle.com>,
        Oliver Upton <oliver.upton@...ux.dev>
Subject: [PATCH v6 4/4] KVM: arm64/mmu: count KVM s2 mmu usage in secondary
 pagetable stats

Count the pages used by KVM in arm64 for stage2 mmu in memory stats
under secondary pagetable stats (e.g. "SecPageTables" in /proc/meminfo)
to give better visibility into the memory consumption of KVM mmu in a
similar way to how normal user page tables are accounted.

Signed-off-by: Yosry Ahmed <yosryahmed@...gle.com>
Reviewed-by: Oliver Upton <oliver.upton@...ux.dev>
---
 arch/arm64/kvm/mmu.c | 36 ++++++++++++++++++++++++++++++++----
 1 file changed, 32 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
index 87f1cd0df36ea..9d5a8e93d2fdc 100644
--- a/arch/arm64/kvm/mmu.c
+++ b/arch/arm64/kvm/mmu.c
@@ -92,9 +92,13 @@ static bool kvm_is_device_pfn(unsigned long pfn)
 static void *stage2_memcache_zalloc_page(void *arg)
 {
 	struct kvm_mmu_memory_cache *mc = arg;
+	void *virt;
 
 	/* Allocated with __GFP_ZERO, so no need to zero */
-	return kvm_mmu_memory_cache_alloc(mc);
+	virt = kvm_mmu_memory_cache_alloc(mc);
+	if (virt)
+		kvm_account_pgtable_pages(virt, 1);
+	return virt;
 }
 
 static void *kvm_host_zalloc_pages_exact(size_t size)
@@ -102,6 +106,21 @@ static void *kvm_host_zalloc_pages_exact(size_t size)
 	return alloc_pages_exact(size, GFP_KERNEL_ACCOUNT | __GFP_ZERO);
 }
 
+static void *kvm_s2_zalloc_pages_exact(size_t size)
+{
+	void *virt = kvm_host_zalloc_pages_exact(size);
+
+	if (virt)
+		kvm_account_pgtable_pages(virt, (size >> PAGE_SHIFT));
+	return virt;
+}
+
+static void kvm_s2_free_pages_exact(void *virt, size_t size)
+{
+	kvm_account_pgtable_pages(virt, -(size >> PAGE_SHIFT));
+	free_pages_exact(virt, size);
+}
+
 static void kvm_host_get_page(void *addr)
 {
 	get_page(virt_to_page(addr));
@@ -112,6 +131,15 @@ static void kvm_host_put_page(void *addr)
 	put_page(virt_to_page(addr));
 }
 
+static void kvm_s2_put_page(void *addr)
+{
+	struct page *p = virt_to_page(addr);
+	/* Dropping last refcount, the page will be freed */
+	if (page_count(p) == 1)
+		kvm_account_pgtable_pages(addr, -1);
+	put_page(p);
+}
+
 static int kvm_host_page_count(void *addr)
 {
 	return page_count(virt_to_page(addr));
@@ -625,10 +653,10 @@ static int get_user_mapping_size(struct kvm *kvm, u64 addr)
 
 static struct kvm_pgtable_mm_ops kvm_s2_mm_ops = {
 	.zalloc_page		= stage2_memcache_zalloc_page,
-	.zalloc_pages_exact	= kvm_host_zalloc_pages_exact,
-	.free_pages_exact	= free_pages_exact,
+	.zalloc_pages_exact	= kvm_s2_zalloc_pages_exact,
+	.free_pages_exact	= kvm_s2_free_pages_exact,
 	.get_page		= kvm_host_get_page,
-	.put_page		= kvm_host_put_page,
+	.put_page		= kvm_s2_put_page,
 	.page_count		= kvm_host_page_count,
 	.phys_to_virt		= kvm_host_va,
 	.virt_to_phys		= kvm_host_pa,
-- 
2.37.0.rc0.161.g10f37bed90-goog