linux-kernel - [PATCH 22/42] KVM: SVM: remove needless mmap_sem acquision from nested_svm

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Date:	Mon, 16 Nov 2009 14:19:23 +0200
From:	Avi Kivity <avi@...hat.com>
To:	linux-kernel@...r.kernel.org
Cc:	kvm@...r.kernel.org
Subject: [PATCH 22/42] KVM: SVM: remove needless mmap_sem acquision from nested_svm_map

From: Marcelo Tosatti <mtosatti@...hat.com>

nested_svm_map unnecessarily takes mmap_sem around gfn_to_page, since
gfn_to_page / get_user_pages are responsible for it.

Signed-off-by: Marcelo Tosatti <mtosatti@...hat.com>
Acked-by: Alexander Graf <agraf@...e.de>
Signed-off-by: Avi Kivity <avi@...hat.com>
---
 arch/x86/kvm/svm.c |    3 ---
 1 files changed, 0 insertions(+), 3 deletions(-)

diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index 92048a6..f54c4f9 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -1396,10 +1396,7 @@ static void *nested_svm_map(struct vcpu_svm *svm, u64 gpa, enum km_type idx)
 {
 	struct page *page;
 
-	down_read(&current->mm->mmap_sem);
 	page = gfn_to_page(svm->vcpu.kvm, gpa >> PAGE_SHIFT);
-	up_read(&current->mm->mmap_sem);
-
 	if (is_error_page(page))
 		goto error;
 
-- 
1.6.5.2

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