linux-kernel - [PATCH 08/15] KVM: MMU: count used shadow pages on preparing path

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Date:	Tue, 07 Jun 2011 21:02:45 +0800
From:	Xiao Guangrong <xiaoguangrong@...fujitsu.com>
To:	Avi Kivity <avi@...hat.com>
CC:	Marcelo Tosatti <mtosatti@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>, KVM <kvm@...r.kernel.org>
Subject: [PATCH 08/15] KVM: MMU: count used shadow pages on preparing path

Move counting used shadow pages from committing path to preparing path to
reduce tlb flush on some paths

Signed-off-by: Xiao Guangrong <xiaoguangrong@...fujitsu.com>
---
 arch/x86/kvm/mmu.c |   10 +++++-----
 1 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 05e604d..43e7ca1 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -1039,7 +1039,7 @@ static inline void kvm_mod_used_mmu_pages(struct kvm *kvm, int nr)
 	percpu_counter_add(&kvm_total_used_mmu_pages, nr);
 }
 
-static void kvm_mmu_free_page(struct kvm *kvm, struct kvm_mmu_page *sp)
+static void kvm_mmu_free_page(struct kvm_mmu_page *sp)
 {
 	ASSERT(is_empty_shadow_page(sp->spt));
 	hlist_del(&sp->hash_link);
@@ -1048,7 +1048,6 @@ static void kvm_mmu_free_page(struct kvm *kvm, struct kvm_mmu_page *sp)
 	if (!sp->role.direct)
 		free_page((unsigned long)sp->gfns);
 	kmem_cache_free(mmu_page_header_cache, sp);
-	kvm_mod_used_mmu_pages(kvm, -1);
 }
 
 static unsigned kvm_page_table_hashfn(gfn_t gfn)
@@ -1655,6 +1654,7 @@ static int kvm_mmu_prepare_zap_page(struct kvm *kvm, struct kvm_mmu_page *sp,
 		/* Count self */
 		ret++;
 		list_move(&sp->link, invalid_list);
+		kvm_mod_used_mmu_pages(kvm, -1);
 	} else {
 		list_move(&sp->link, &kvm->arch.active_mmu_pages);
 		kvm_reload_remote_mmus(kvm);
@@ -1678,7 +1678,7 @@ static void kvm_mmu_commit_zap_page(struct kvm *kvm,
 	do {
 		sp = list_first_entry(invalid_list, struct kvm_mmu_page, link);
 		WARN_ON(!sp->role.invalid || sp->root_count);
-		kvm_mmu_free_page(kvm, sp);
+		kvm_mmu_free_page(sp);
 	} while (!list_empty(invalid_list));
 
 }
@@ -1704,8 +1704,8 @@ void kvm_mmu_change_mmu_pages(struct kvm *kvm, unsigned int goal_nr_mmu_pages)
 			page = container_of(kvm->arch.active_mmu_pages.prev,
 					    struct kvm_mmu_page, link);
 			kvm_mmu_prepare_zap_page(kvm, page, &invalid_list);
-			kvm_mmu_commit_zap_page(kvm, &invalid_list);
 		}
+		kvm_mmu_commit_zap_page(kvm, &invalid_list);
 		goal_nr_mmu_pages = kvm->arch.n_used_mmu_pages;
 	}
 
@@ -3290,9 +3290,9 @@ void __kvm_mmu_free_some_pages(struct kvm_vcpu *vcpu)
 		sp = container_of(vcpu->kvm->arch.active_mmu_pages.prev,
 				  struct kvm_mmu_page, link);
 		kvm_mmu_prepare_zap_page(vcpu->kvm, sp, &invalid_list);
-		kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
 		++vcpu->kvm->stat.mmu_recycled;
 	}
+	kvm_mmu_commit_zap_page(vcpu->kvm, &invalid_list);
 }
 
 int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gva_t cr2, u32 error_code,
-- 
1.7.4.4

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