[patch 21/71] KVM: MMU: protect kvm_mmu_change_mmu_pages with mmu_lock

[Greg KH]

2.6.30-stable review patch.  If anyone has any objections, please let us know.

------------------
From: Marcelo Tosatti <mtosatti@xxxxxxxxxx>

(cherry picked from commit 7c8a83b75a38a807d37f5a4398eca2a42c8cf513)

kvm_handle_hva, called by MMU notifiers, manipulates mmu data only with
the protection of mmu_lock.

Update kvm_mmu_change_mmu_pages callers to take mmu_lock, thus protecting
against kvm_handle_hva.

Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
Signed-off-by: Avi Kivity <avi@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
---
 arch/x86/kvm/mmu.c |    2 --
 arch/x86/kvm/x86.c |    6 ++++++
 2 files changed, 6 insertions(+), 2 deletions(-)

--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2729,7 +2729,6 @@ void kvm_mmu_slot_remove_write_access(st
 {
 	struct kvm_mmu_page *sp;
 
-	spin_lock(&kvm->mmu_lock);
 	list_for_each_entry(sp, &kvm->arch.active_mmu_pages, link) {
 		int i;
 		u64 *pt;
@@ -2744,7 +2743,6 @@ void kvm_mmu_slot_remove_write_access(st
 				pt[i] &= ~PT_WRITABLE_MASK;
 	}
 	kvm_flush_remote_tlbs(kvm);
-	spin_unlock(&kvm->mmu_lock);
 }
 
 void kvm_mmu_zap_all(struct kvm *kvm)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1608,10 +1608,12 @@ static int kvm_vm_ioctl_set_nr_mmu_pages
 		return -EINVAL;
 
 	down_write(&kvm->slots_lock);
+	spin_lock(&kvm->mmu_lock);
 
 	kvm_mmu_change_mmu_pages(kvm, kvm_nr_mmu_pages);
 	kvm->arch.n_requested_mmu_pages = kvm_nr_mmu_pages;
 
+	spin_unlock(&kvm->mmu_lock);
 	up_write(&kvm->slots_lock);
 	return 0;
 }
@@ -1787,7 +1789,9 @@ int kvm_vm_ioctl_get_dirty_log(struct kv
 
 	/* If nothing is dirty, don't bother messing with page tables. */
 	if (is_dirty) {
+		spin_lock(&kvm->mmu_lock);
 		kvm_mmu_slot_remove_write_access(kvm, log->slot);
+		spin_unlock(&kvm->mmu_lock);
 		kvm_flush_remote_tlbs(kvm);
 		memslot = &kvm->memslots[log->slot];
 		n = ALIGN(memslot->npages, BITS_PER_LONG) / 8;
@@ -4419,12 +4423,14 @@ int kvm_arch_set_memory_region(struct kv
 		}
 	}
 
+	spin_lock(&kvm->mmu_lock);
 	if (!kvm->arch.n_requested_mmu_pages) {
 		unsigned int nr_mmu_pages = kvm_mmu_calculate_mmu_pages(kvm);
 		kvm_mmu_change_mmu_pages(kvm, nr_mmu_pages);
 	}
 
 	kvm_mmu_slot_remove_write_access(kvm, mem->slot);
+	spin_unlock(&kvm->mmu_lock);
 	kvm_flush_remote_tlbs(kvm);
 
 	return 0;


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