KVM: Allow reading aliases with mmu_lock
This allows the mmu notifier code to run unalias_gfn with only the
mmu_lock held. Only alias writes need the mmu_lock held. Readers will
either take the slots_lock in read mode or the mmu_lock.
Signed-off-by: Andrea Arcangeli <andrea@qumranet.com>
Signed-off-by: Avi Kivity <avi@qumranet.com>
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 5916191..9870ce4 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1495,6 +1495,7 @@
goto out;
down_write(&kvm->slots_lock);
+ spin_lock(&kvm->mmu_lock);
p = &kvm->arch.aliases[alias->slot];
p->base_gfn = alias->guest_phys_addr >> PAGE_SHIFT;
@@ -1506,6 +1507,7 @@
break;
kvm->arch.naliases = n;
+ spin_unlock(&kvm->mmu_lock);
kvm_mmu_zap_all(kvm);
up_write(&kvm->slots_lock);