linux-kernel - [PATCH v12 65/84] KVM: LoongArch: Mark "struct page" pfns accessed only in "slow" page fault path

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Message-ID: <20240726235234.228822-66-seanjc@google.com>
Date: Fri, 26 Jul 2024 16:52:14 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Paolo Bonzini <pbonzini@...hat.com>, Marc Zyngier <maz@...nel.org>, 
	Oliver Upton <oliver.upton@...ux.dev>, Tianrui Zhao <zhaotianrui@...ngson.cn>, 
	Bibo Mao <maobibo@...ngson.cn>, Huacai Chen <chenhuacai@...nel.org>, 
	Michael Ellerman <mpe@...erman.id.au>, Anup Patel <anup@...infault.org>, 
	Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt <palmer@...belt.com>, 
	Albert Ou <aou@...s.berkeley.edu>, Christian Borntraeger <borntraeger@...ux.ibm.com>, 
	Janosch Frank <frankja@...ux.ibm.com>, Claudio Imbrenda <imbrenda@...ux.ibm.com>, 
	Sean Christopherson <seanjc@...gle.com>
Cc: kvm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
	kvmarm@...ts.linux.dev, loongarch@...ts.linux.dev, linux-mips@...r.kernel.org, 
	linuxppc-dev@...ts.ozlabs.org, kvm-riscv@...ts.infradead.org, 
	linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	David Matlack <dmatlack@...gle.com>, David Stevens <stevensd@...omium.org>
Subject: [PATCH v12 65/84] KVM: LoongArch: Mark "struct page" pfns accessed
 only in "slow" page fault path

Mark pages accessed only in the slow path, before dropping mmu_lock when
faulting in guest memory so that LoongArch can convert to
kvm_release_faultin_page() without tripping its lockdep assertion on
mmu_lock being held.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/loongarch/kvm/mmu.c | 20 ++------------------
 1 file changed, 2 insertions(+), 18 deletions(-)

diff --git a/arch/loongarch/kvm/mmu.c b/arch/loongarch/kvm/mmu.c
index 364dd35e0557..52b5c16cf250 100644
--- a/arch/loongarch/kvm/mmu.c
+++ b/arch/loongarch/kvm/mmu.c
@@ -552,12 +552,10 @@ bool kvm_test_age_gfn(struct kvm *kvm, struct kvm_gfn_range *range)
 static int kvm_map_page_fast(struct kvm_vcpu *vcpu, unsigned long gpa, bool write)
 {
 	int ret = 0;
-	kvm_pfn_t pfn = 0;
 	kvm_pte_t *ptep, changed, new;
 	gfn_t gfn = gpa >> PAGE_SHIFT;
 	struct kvm *kvm = vcpu->kvm;
 	struct kvm_memory_slot *slot;
-	struct page *page;
 
 	spin_lock(&kvm->mmu_lock);
 
@@ -570,8 +568,6 @@ static int kvm_map_page_fast(struct kvm_vcpu *vcpu, unsigned long gpa, bool writ
 
 	/* Track access to pages marked old */
 	new = kvm_pte_mkyoung(*ptep);
-	/* call kvm_set_pfn_accessed() after unlock */
-
 	if (write && !kvm_pte_dirty(new)) {
 		if (!kvm_pte_write(new)) {
 			ret = -EFAULT;
@@ -595,23 +591,11 @@ static int kvm_map_page_fast(struct kvm_vcpu *vcpu, unsigned long gpa, bool writ
 	}
 
 	changed = new ^ (*ptep);
-	if (changed) {
+	if (changed)
 		kvm_set_pte(ptep, new);
-		pfn = kvm_pte_pfn(new);
-		page = kvm_pfn_to_refcounted_page(pfn);
-		if (page)
-			get_page(page);
-	}
+
 	spin_unlock(&kvm->mmu_lock);
 
-	if (changed) {
-		if (kvm_pte_young(changed))
-			kvm_set_pfn_accessed(pfn);
-
-		if (page)
-			put_page(page);
-	}
-
 	if (kvm_pte_dirty(changed))
 		mark_page_dirty(kvm, gfn);
 
-- 
2.46.0.rc1.232.g9752f9e123-goog