linux-kernel - [PATCH 4.9 19/31] kvm: x86: Do not release the page inside mmu_set

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Date:   Fri, 15 Nov 2019 14:20:48 +0800
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Junaid Shahid <junaids@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Ben Hutchings <ben@...adent.org.uk>
Subject: [PATCH 4.9 19/31] kvm: x86: Do not release the page inside mmu_set_spte()

From: Junaid Shahid <junaids@...gle.com>

commit 43fdcda96e2550c6d1c46fb8a78801aa2f7276ed upstream.

Release the page at the call-site where it was originally acquired.
This makes the exit code cleaner for most call sites, since they
do not need to duplicate code between success and the failure
label.

Signed-off-by: Junaid Shahid <junaids@...gle.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/x86/kvm/mmu.c         |   18 +++++++-----------
 arch/x86/kvm/paging_tmpl.h |    8 +++-----
 2 files changed, 10 insertions(+), 16 deletions(-)

--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2671,8 +2671,6 @@ static int mmu_set_spte(struct kvm_vcpu
 		}
 	}
 
-	kvm_release_pfn_clean(pfn);
-
 	return ret;
 }
 
@@ -2707,9 +2705,11 @@ static int direct_pte_prefetch_many(stru
 	if (ret <= 0)
 		return -1;
 
-	for (i = 0; i < ret; i++, gfn++, start++)
+	for (i = 0; i < ret; i++, gfn++, start++) {
 		mmu_set_spte(vcpu, start, access, 0, sp->role.level, gfn,
 			     page_to_pfn(pages[i]), true, true);
+		put_page(pages[i]);
+	}
 
 	return 0;
 }
@@ -3055,6 +3055,7 @@ static int nonpaging_map(struct kvm_vcpu
 	if (handle_abnormal_pfn(vcpu, v, gfn, pfn, ACC_ALL, &r))
 		return r;
 
+	r = RET_PF_RETRY;
 	spin_lock(&vcpu->kvm->mmu_lock);
 	if (mmu_notifier_retry(vcpu->kvm, mmu_seq))
 		goto out_unlock;
@@ -3062,14 +3063,11 @@ static int nonpaging_map(struct kvm_vcpu
 	if (likely(!force_pt_level))
 		transparent_hugepage_adjust(vcpu, &gfn, &pfn, &level);
 	r = __direct_map(vcpu, write, map_writable, level, gfn, pfn, prefault);
-	spin_unlock(&vcpu->kvm->mmu_lock);
-
-	return r;
 
 out_unlock:
 	spin_unlock(&vcpu->kvm->mmu_lock);
 	kvm_release_pfn_clean(pfn);
-	return RET_PF_RETRY;
+	return r;
 }
 
 
@@ -3593,6 +3591,7 @@ static int tdp_page_fault(struct kvm_vcp
 	if (handle_abnormal_pfn(vcpu, 0, gfn, pfn, ACC_ALL, &r))
 		return r;
 
+	r = RET_PF_RETRY;
 	spin_lock(&vcpu->kvm->mmu_lock);
 	if (mmu_notifier_retry(vcpu->kvm, mmu_seq))
 		goto out_unlock;
@@ -3600,14 +3599,11 @@ static int tdp_page_fault(struct kvm_vcp
 	if (likely(!force_pt_level))
 		transparent_hugepage_adjust(vcpu, &gfn, &pfn, &level);
 	r = __direct_map(vcpu, write, map_writable, level, gfn, pfn, prefault);
-	spin_unlock(&vcpu->kvm->mmu_lock);
-
-	return r;
 
 out_unlock:
 	spin_unlock(&vcpu->kvm->mmu_lock);
 	kvm_release_pfn_clean(pfn);
-	return RET_PF_RETRY;
+	return r;
 }
 
 static void nonpaging_init_context(struct kvm_vcpu *vcpu,
--- a/arch/x86/kvm/paging_tmpl.h
+++ b/arch/x86/kvm/paging_tmpl.h
@@ -499,6 +499,7 @@ FNAME(prefetch_gpte)(struct kvm_vcpu *vc
 	mmu_set_spte(vcpu, spte, pte_access, 0, PT_PAGE_TABLE_LEVEL, gfn, pfn,
 		     true, true);
 
+	kvm_release_pfn_clean(pfn);
 	return true;
 }
 
@@ -650,7 +651,6 @@ static int FNAME(fetch)(struct kvm_vcpu
 	return ret;
 
 out_gpte_changed:
-	kvm_release_pfn_clean(pfn);
 	return RET_PF_RETRY;
 }
 
@@ -799,6 +799,7 @@ static int FNAME(page_fault)(struct kvm_
 			walker.pte_access &= ~ACC_EXEC_MASK;
 	}
 
+	r = RET_PF_RETRY;
 	spin_lock(&vcpu->kvm->mmu_lock);
 	if (mmu_notifier_retry(vcpu->kvm, mmu_seq))
 		goto out_unlock;
@@ -811,14 +812,11 @@ static int FNAME(page_fault)(struct kvm_
 			 level, pfn, map_writable, prefault);
 	++vcpu->stat.pf_fixed;
 	kvm_mmu_audit(vcpu, AUDIT_POST_PAGE_FAULT);
-	spin_unlock(&vcpu->kvm->mmu_lock);
-
-	return r;
 
 out_unlock:
 	spin_unlock(&vcpu->kvm->mmu_lock);
 	kvm_release_pfn_clean(pfn);
-	return RET_PF_RETRY;
+	return r;
 }
 
 static gpa_t FNAME(get_level1_sp_gpa)(struct kvm_mmu_page *sp)