[PATCH 2/6] kvm.git allow reading aliases with mmu_lock

Andrea Arcangeli
2008-07-25T14:26:41Z

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>

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index f7726a0..ddaf960 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1515,6 +1515,7 @@ static int kvm_vm_ioctl_set_memory_alias(struct kvm *kvm,
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;
@@ -1526,6 +1527,7 @@ static int kvm_vm_ioctl_set_memory_alias(struct kvm *kvm,
break;
kvm->arch.naliases = n;

+ spin_unlock(&kvm->mmu_lock);
kvm_mmu_zap_all(kvm);

up_write(&kvm->slots_lock);