linux-kernel - [PATCH 3/4] KVM: Refactor mark_page_dirty_in

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Message-Id: <20230116040405.260935-4-gshan@redhat.com>
Date:   Mon, 16 Jan 2023 12:04:04 +0800
From:   Gavin Shan <gshan@...hat.com>
To:     kvmarm@...ts.linux.dev
Cc:     kvmarm@...ts.cs.columbia.edu, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, pbonzini@...hat.com, maz@...nel.org,
        corbet@....net, james.morse@....com, suzuki.poulose@....com,
        oliver.upton@...ux.dev, yuzenghui@...wei.com,
        catalin.marinas@....com, will@...nel.org, ricarkol@...gle.com,
        eric.auger@...hat.com, yuzhe@...china.com, renzhengeek@...il.com,
        ardb@...nel.org, peterx@...hat.com, seanjc@...gle.com,
        shan.gavin@...il.com
Subject: [PATCH 3/4] KVM: Refactor mark_page_dirty_in_slot()

Refactor mark_page_dirty_in_slot() to bail early if the memory slot
isn't existing or dirty page tracking is disabled on it. It's the
preparatory work for the forth coming fixes.

No functional change intended.

Signed-off-by: Gavin Shan <gshan@...hat.com>
---
 virt/kvm/kvm_main.c | 19 +++++++++++--------
 1 file changed, 11 insertions(+), 8 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 9c60384b5ae0..90f538433916 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3317,6 +3317,8 @@ void mark_page_dirty_in_slot(struct kvm *kvm,
 		 	     gfn_t gfn)
 {
 	struct kvm_vcpu *vcpu = kvm_get_running_vcpu();
+	unsigned long rel_gfn;
+	u32 slot;
 
 #ifdef CONFIG_HAVE_KVM_DIRTY_RING
 	if (WARN_ON_ONCE(vcpu && vcpu->kvm != kvm))
@@ -3325,15 +3327,16 @@ void mark_page_dirty_in_slot(struct kvm *kvm,
 	WARN_ON_ONCE(!vcpu && !kvm_arch_allow_write_without_running_vcpu(kvm));
 #endif
 
-	if (memslot && kvm_slot_dirty_track_enabled(memslot)) {
-		unsigned long rel_gfn = gfn - memslot->base_gfn;
-		u32 slot = (memslot->as_id << 16) | memslot->id;
+	if (!memslot || !kvm_slot_dirty_track_enabled(memslot))
+		return;
 
-		if (kvm->dirty_ring_size && vcpu)
-			kvm_dirty_ring_push(vcpu, slot, rel_gfn);
-		else if (memslot->dirty_bitmap)
-			set_bit_le(rel_gfn, memslot->dirty_bitmap);
-	}
+	rel_gfn = gfn - memslot->base_gfn;
+	slot = (memslot->as_id << 16) | memslot->id;
+
+	if (kvm->dirty_ring_size && vcpu)
+		kvm_dirty_ring_push(vcpu, slot, rel_gfn);
+	else if (memslot->dirty_bitmap)
+		set_bit_le(rel_gfn, memslot->dirty_bitmap);
 }
 EXPORT_SYMBOL_GPL(mark_page_dirty_in_slot);
 
-- 
2.23.0