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KVM: use SRCU for dirty log

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Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
This commit is contained in:
Marcelo Tosatti 2009-12-23 14:35:22 -02:00
parent bc6678a33d
commit b050b015ab
1 changed files with 41 additions and 8 deletions
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49
arch/x86/kvm/x86.c
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@ -2415,27 +2415,60 @@ static int kvm_vm_ioctl_reinject(struct kvm *kvm,
int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm,
struct kvm_dirty_log *log)
{
int r;
int n;
int r, n, i;
struct kvm_memory_slot *memslot;
int is_dirty = 0;
unsigned long is_dirty = 0;
unsigned long *dirty_bitmap = NULL;
down_write(&kvm->slots_lock);
r = kvm_get_dirty_log(kvm, log, &is_dirty);
if (r)
r = -EINVAL;
if (log->slot >= KVM_MEMORY_SLOTS)
goto out;
memslot = &kvm->memslots->memslots[log->slot];
r = -ENOENT;
if (!memslot->dirty_bitmap)
goto out;
n = ALIGN(memslot->npages, BITS_PER_LONG) / 8;
r = -ENOMEM;
dirty_bitmap = vmalloc(n);
if (!dirty_bitmap)
goto out;
memset(dirty_bitmap, 0, n);
for (i = 0; !is_dirty && i < n/sizeof(long); i++)
is_dirty = memslot->dirty_bitmap[i];
/* If nothing is dirty, don't bother messing with page tables. */
if (is_dirty) {
struct kvm_memslots *slots, *old_slots;
spin_lock(&kvm->mmu_lock);
kvm_mmu_slot_remove_write_access(kvm, log->slot);
spin_unlock(&kvm->mmu_lock);
memslot = &kvm->memslots->memslots[log->slot];
n = ALIGN(memslot->npages, BITS_PER_LONG) / 8;
memset(memslot->dirty_bitmap, 0, n);
slots = kzalloc(sizeof(struct kvm_memslots), GFP_KERNEL);
if (!slots)
goto out_free;
memcpy(slots, kvm->memslots, sizeof(struct kvm_memslots));
slots->memslots[log->slot].dirty_bitmap = dirty_bitmap;
old_slots = kvm->memslots;
rcu_assign_pointer(kvm->memslots, slots);
synchronize_srcu_expedited(&kvm->srcu);
dirty_bitmap = old_slots->memslots[log->slot].dirty_bitmap;
kfree(old_slots);
}
r = 0;
if (copy_to_user(log->dirty_bitmap, dirty_bitmap, n))
r = -EFAULT;
out_free:
vfree(dirty_bitmap);
out:
up_write(&kvm->slots_lock);
return r;