diff options
| -rw-r--r-- | arch/x86/kvm/x86.c | 16 | ||||
| -rw-r--r-- | include/linux/kvm_host.h | 1 | ||||
| -rw-r--r-- | virt/kvm/kvm_main.c | 11 |
3 files changed, 15 insertions, 13 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index a2a785472431..35f82f2c66f6 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3208,18 +3208,15 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, struct kvm_memslots *slots, *old_slots; unsigned long *dirty_bitmap; - r = -ENOMEM; - dirty_bitmap = vmalloc(n); - if (!dirty_bitmap) - goto out; + dirty_bitmap = memslot->dirty_bitmap_head; + if (memslot->dirty_bitmap == dirty_bitmap) + dirty_bitmap += n / sizeof(long); memset(dirty_bitmap, 0, n); r = -ENOMEM; slots = kzalloc(sizeof(struct kvm_memslots), GFP_KERNEL); - if (!slots) { - vfree(dirty_bitmap); + if (!slots) goto out; - } memcpy(slots, kvm->memslots, sizeof(struct kvm_memslots)); slots->memslots[log->slot].dirty_bitmap = dirty_bitmap; slots->generation++; @@ -3235,11 +3232,8 @@ int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, spin_unlock(&kvm->mmu_lock); r = -EFAULT; - if (copy_to_user(log->dirty_bitmap, dirty_bitmap, n)) { - vfree(dirty_bitmap); + if (copy_to_user(log->dirty_bitmap, dirty_bitmap, n)) goto out; - } - vfree(dirty_bitmap); } else { r = -EFAULT; if (clear_user(log->dirty_bitmap, n)) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 462b982fedfb..bcf71c7730f0 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -150,6 +150,7 @@ struct kvm_memory_slot { unsigned long flags; unsigned long *rmap; unsigned long *dirty_bitmap; + unsigned long *dirty_bitmap_head; struct { unsigned long rmap_pde; int write_count; diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 0021c2862140..27649fdaa007 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -449,8 +449,9 @@ static void kvm_destroy_dirty_bitmap(struct kvm_memory_slot *memslot) if (!memslot->dirty_bitmap) return; - vfree(memslot->dirty_bitmap); + vfree(memslot->dirty_bitmap_head); memslot->dirty_bitmap = NULL; + memslot->dirty_bitmap_head = NULL; } /* @@ -537,15 +538,21 @@ static int kvm_vm_release(struct inode *inode, struct file *filp) return 0; } +/* + * Allocation size is twice as large as the actual dirty bitmap size. + * This makes it possible to do double buffering: see x86's + * kvm_vm_ioctl_get_dirty_log(). + */ static int kvm_create_dirty_bitmap(struct kvm_memory_slot *memslot) { - unsigned long dirty_bytes = kvm_dirty_bitmap_bytes(memslot); + unsigned long dirty_bytes = 2 * kvm_dirty_bitmap_bytes(memslot); memslot->dirty_bitmap = vmalloc(dirty_bytes); if (!memslot->dirty_bitmap) return -ENOMEM; memset(memslot->dirty_bitmap, 0, dirty_bytes); + memslot->dirty_bitmap_head = memslot->dirty_bitmap; return 0; } |