linux-kernel - [PATCH 1/3] KVM: MMU: release noslot pfn on the fail path properly

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Message-ID: <5049908A.7070501@linux.vnet.ibm.com>
Date:	Fri, 07 Sep 2012 14:13:30 +0800
From:	Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.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 1/3] KVM: MMU: release noslot pfn on the fail path properly

We can not directly call kvm_release_pfn_clean to release the pfn
since we can meet noslot pfn which is used to cache mmio info into
spte

Introduce mmu_release_pfn_clean to do this kind of thing

Signed-off-by: Xiao Guangrong <xiaoguangrong@...ux.vnet.ibm.com>
---
 arch/x86/kvm/mmu.c         |   19 ++++++++++++++-----
 arch/x86/kvm/paging_tmpl.h |    4 ++--
 2 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 399c177..3c10bca 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2432,6 +2432,16 @@ done:
 	return ret;
 }

+/*
+ * The primary user is page fault path which call it to properly
+ * release noslot_pfn.
+ */
+static void mmu_release_pfn_clean(pfn_t pfn)
+{
+	if (!is_error_pfn(pfn))
+		kvm_release_pfn_clean(pfn);
+}
+
 static void mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
 			 unsigned pt_access, unsigned pte_access,
 			 int user_fault, int write_fault,
@@ -2497,8 +2507,7 @@ static void mmu_set_spte(struct kvm_vcpu *vcpu, u64 *sptep,
 		}
 	}

-	if (!is_error_pfn(pfn))
-		kvm_release_pfn_clean(pfn);
+	mmu_release_pfn_clean(pfn);
 }

 static void nonpaging_new_cr3(struct kvm_vcpu *vcpu)
@@ -2618,7 +2627,7 @@ static int __direct_map(struct kvm_vcpu *vcpu, gpa_t v, int write,
 					      1, ACC_ALL, iterator.sptep);
 			if (!sp) {
 				pgprintk("nonpaging_map: ENOMEM\n");
-				kvm_release_pfn_clean(pfn);
+				mmu_release_pfn_clean(pfn);
 				return -ENOMEM;
 			}

@@ -2882,7 +2891,7 @@ static int nonpaging_map(struct kvm_vcpu *vcpu, gva_t v, u32 error_code,

 out_unlock:
 	spin_unlock(&vcpu->kvm->mmu_lock);
-	kvm_release_pfn_clean(pfn);
+	mmu_release_pfn_clean(pfn);
 	return 0;
 }

@@ -3350,7 +3359,7 @@ static int tdp_page_fault(struct kvm_vcpu *vcpu, gva_t gpa, u32 error_code,

 out_unlock:
 	spin_unlock(&vcpu->kvm->mmu_lock);
-	kvm_release_pfn_clean(pfn);
+	mmu_release_pfn_clean(pfn);
 	return 0;
 }

diff --git a/arch/x86/kvm/paging_tmpl.h b/arch/x86/kvm/paging_tmpl.h
index bf8c42b..f075259 100644
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -544,7 +544,7 @@ static u64 *FNAME(fetch)(struct kvm_vcpu *vcpu, gva_t addr,
 out_gpte_changed:
 	if (sp)
 		kvm_mmu_put_page(sp, it.sptep);
-	kvm_release_pfn_clean(pfn);
+	mmu_release_pfn_clean(pfn);
 	return NULL;
 }

@@ -645,7 +645,7 @@ static int FNAME(page_fault)(struct kvm_vcpu *vcpu, gva_t addr, u32 error_code,

 out_unlock:
 	spin_unlock(&vcpu->kvm->mmu_lock);
-	kvm_release_pfn_clean(pfn);
+	mmu_release_pfn_clean(pfn);
 	return 0;
 }

-- 
1.7.7.6

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