KVM: MMU: kvm_pv_mmu_op should not take mmap_sem

kvm_pv_mmu_op should not take mmap_sem. All gfn_to_page() callers down
in the MMU processing will take it if necessary, so as it is it can
deadlock.

Apparently a leftover from the days before slots_lock.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>

1 files changed, 0 insertions, 3 deletions

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 078a7f1ac34c..2ad6f5481671 100644
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -2173,8 +2173,6 @@ int kvm_pv_mmu_op(struct kvm_vcpu *vcpu, unsigned long bytes,
         int r;
         struct kvm_pv_mmu_op_buffer buffer;
 
-        down_read(&current->mm->mmap_sem);
-
         buffer.ptr = buffer.buf;
         buffer.len = min_t(unsigned long, bytes, sizeof buffer.buf);
         buffer.processed = 0;
@@ -2194,7 +2192,6 @@ int kvm_pv_mmu_op(struct kvm_vcpu *vcpu, unsigned long bytes,
         r = 1;
 out:
         *ret = buffer.processed;
-        up_read(&current->mm->mmap_sem);
         return r;
 }