linux-kernel - [PATCH 08/10] KVM: x86: MMU: Use for_each_rmap_spte macro instead of pte_list

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Message-Id: <20151120174717.7b0c31caa267aa83027e8d8f@lab.ntt.co.jp>
Date:	Fri, 20 Nov 2015 17:47:17 +0900
From:	Takuya Yoshikawa <yoshikawa_takuya_b1@....ntt.co.jp>
To:	pbonzini@...hat.com
Cc:	kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
	mtosatti@...hat.com, guangrong.xiao@...ux.intel.com
Subject: [PATCH 08/10] KVM: x86: MMU: Use for_each_rmap_spte macro instead
 of pte_list_walk()

kvm_mmu_mark_parents_unsync() alone uses pte_list_walk(), witch does
nearly the same as the for_each_rmap_spte macro.  The only difference
is that is_shadow_present_pte() checks cannot be placed there because
kvm_mmu_mark_parents_unsync() can be called with a new parent pointer
whose entry is not set yet.

By calling mark_unsync() separately for the parent and adding the parent
pointer to the parent_ptes chain later in kvm_mmu_get_page(), the macro
works with no problem.

Signed-off-by: Takuya Yoshikawa <yoshikawa_takuya_b1@....ntt.co.jp>
---
 arch/x86/kvm/mmu.c | 36 +++++++++++++-----------------------
 1 file changed, 13 insertions(+), 23 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 7f46e3e..4e29d9a 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1007,26 +1007,6 @@ static void pte_list_remove(u64 *spte, struct kvm_rmap_head *rmap_head)
 	}
 }
 
-typedef void (*pte_list_walk_fn) (u64 *spte);
-static void pte_list_walk(struct kvm_rmap_head *rmap_head, pte_list_walk_fn fn)
-{
-	struct pte_list_desc *desc;
-	int i;
-
-	if (!rmap_head->val)
-		return;
-
-	if (!(rmap_head->val & 1))
-		return fn((u64 *)rmap_head->val);
-
-	desc = (struct pte_list_desc *)(rmap_head->val & ~1ul);
-	while (desc) {
-		for (i = 0; i < PTE_LIST_EXT && desc->sptes[i]; ++i)
-			fn(desc->sptes[i]);
-		desc = desc->more;
-	}
-}
-
 static struct kvm_rmap_head *__gfn_to_rmap(gfn_t gfn, int level,
 					   struct kvm_memory_slot *slot)
 {
@@ -1749,7 +1729,12 @@ static struct kvm_mmu_page *kvm_mmu_alloc_page(struct kvm_vcpu *vcpu, int direct
 static void mark_unsync(u64 *spte);
 static void kvm_mmu_mark_parents_unsync(struct kvm_mmu_page *sp)
 {
-	pte_list_walk(&sp->parent_ptes, mark_unsync);
+	u64 *sptep;
+	struct rmap_iterator iter;
+
+	for_each_rmap_spte(&sp->parent_ptes, &iter, sptep) {
+		mark_unsync(sptep);
+	}
 }
 
 static void mark_unsync(u64 *spte)
@@ -2119,12 +2104,17 @@ static struct kvm_mmu_page *kvm_mmu_get_page(struct kvm_vcpu *vcpu,
 		if (sp->unsync && kvm_sync_page_transient(vcpu, sp))
 			break;
 
-		mmu_page_add_parent_pte(vcpu, sp, parent_pte);
 		if (sp->unsync_children) {
 			kvm_make_request(KVM_REQ_MMU_SYNC, vcpu);
 			kvm_mmu_mark_parents_unsync(sp);
-		} else if (sp->unsync)
+			if (parent_pte)
+				mark_unsync(parent_pte);
+		} else if (sp->unsync) {
 			kvm_mmu_mark_parents_unsync(sp);
+			if (parent_pte)
+				mark_unsync(parent_pte);
+		}
+		mmu_page_add_parent_pte(vcpu, sp, parent_pte);
 
 		__clear_sp_write_flooding_count(sp);
 		trace_kvm_mmu_get_page(sp, false);
-- 
2.1.0

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