lkml.org 
[lkml]   [2009]   [Aug]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 29/46] KVM: MMU: fix missing locking in alloc_mmu_pages
Date
From: Marcelo Tosatti <mtosatti@redhat.com>

n_requested_mmu_pages/n_free_mmu_pages are used by
kvm_mmu_change_mmu_pages to calculate the number of pages to zap.

alloc_mmu_pages, called from the vcpu initialization path, modifies this
variables without proper locking, which can result in a negative value
in kvm_mmu_change_mmu_pages (say, with cpu hotplug).

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
---
arch/x86/kvm/mmu.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 87c67f4..86c2551 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2728,12 +2728,14 @@ static int alloc_mmu_pages(struct kvm_vcpu *vcpu)

ASSERT(vcpu);

+ spin_lock(&vcpu->kvm->mmu_lock);
if (vcpu->kvm->arch.n_requested_mmu_pages)
vcpu->kvm->arch.n_free_mmu_pages =
vcpu->kvm->arch.n_requested_mmu_pages;
else
vcpu->kvm->arch.n_free_mmu_pages =
vcpu->kvm->arch.n_alloc_mmu_pages;
+ spin_unlock(&vcpu->kvm->mmu_lock);
/*
* When emulating 32-bit mode, cr3 is only 32 bits even on x86_64.
* Therefore we need to allocate shadow page tables in the first
--
1.6.4.1


\
 
 \ /
  Last update: 2009-08-23 14:11    [W:0.103 / U:0.736 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site