diff options
Diffstat (limited to 'virt/kvm/kvm_main.c')
| -rw-r--r-- | virt/kvm/kvm_main.c | 91 |
1 files changed, 71 insertions, 20 deletions
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 1632e466ad6f..7420aa468b75 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -856,7 +856,7 @@ static int kvm_vm_release(struct inode *inode, struct file *filp) /* * Allocation size is twice as large as the actual dirty bitmap size. - * See x86's kvm_vm_ioctl_get_dirty_log() why this is needed. + * See kvm_vm_ioctl_get_dirty_log() why this is needed. */ static int kvm_create_dirty_bitmap(struct kvm_memory_slot *memslot) { @@ -1104,12 +1104,9 @@ int __kvm_set_memory_region(struct kvm *kvm, * Make a full copy of the old memslot, the pointer will become stale * when the memslots are re-sorted by update_memslots(), and the old * memslot needs to be referenced after calling update_memslots(), e.g. - * to free its resources and for arch specific behavior. Kill @tmp - * after making a copy to deter potentially dangerous usage. + * to free its resources and for arch specific behavior. */ - tmp = id_to_memslot(__kvm_memslots(kvm, as_id), id); - old = *tmp; - tmp = NULL; + old = *id_to_memslot(__kvm_memslots(kvm, as_id), id); if (!mem->memory_size) return kvm_delete_memslot(kvm, mem, &old, as_id); @@ -1201,6 +1198,7 @@ static int kvm_vm_ioctl_set_memory_region(struct kvm *kvm, return kvm_set_memory_region(kvm, mem); } +#ifndef CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT int kvm_get_dirty_log(struct kvm *kvm, struct kvm_dirty_log *log, int *is_dirty) { @@ -1234,13 +1232,12 @@ int kvm_get_dirty_log(struct kvm *kvm, } EXPORT_SYMBOL_GPL(kvm_get_dirty_log); -#ifdef CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT +#else /* CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT */ /** * kvm_get_dirty_log_protect - get a snapshot of dirty pages * and reenable dirty page tracking for the corresponding pages. * @kvm: pointer to kvm instance * @log: slot id and address to which we copy the log - * @flush: true if TLB flush is needed by caller * * We need to keep it in mind that VCPU threads can write to the bitmap * concurrently. So, to avoid losing track of dirty pages we keep the @@ -1257,8 +1254,7 @@ EXPORT_SYMBOL_GPL(kvm_get_dirty_log); * exiting to userspace will be logged for the next call. * */ -int kvm_get_dirty_log_protect(struct kvm *kvm, - struct kvm_dirty_log *log, bool *flush) +static int kvm_get_dirty_log_protect(struct kvm *kvm, struct kvm_dirty_log *log) { struct kvm_memslots *slots; struct kvm_memory_slot *memslot; @@ -1266,6 +1262,7 @@ int kvm_get_dirty_log_protect(struct kvm *kvm, unsigned long n; unsigned long *dirty_bitmap; unsigned long *dirty_bitmap_buffer; + bool flush; as_id = log->slot >> 16; id = (u16)log->slot; @@ -1279,8 +1276,10 @@ int kvm_get_dirty_log_protect(struct kvm *kvm, if (!dirty_bitmap) return -ENOENT; + kvm_arch_sync_dirty_log(kvm, memslot); + n = kvm_dirty_bitmap_bytes(memslot); - *flush = false; + flush = false; if (kvm->manual_dirty_log_protect) { /* * Unlike kvm_get_dirty_log, we always return false in *flush, @@ -1303,7 +1302,7 @@ int kvm_get_dirty_log_protect(struct kvm *kvm, if (!dirty_bitmap[i]) continue; - *flush = true; + flush = true; mask = xchg(&dirty_bitmap[i], 0); dirty_bitmap_buffer[i] = mask; @@ -1314,21 +1313,55 @@ int kvm_get_dirty_log_protect(struct kvm *kvm, spin_unlock(&kvm->mmu_lock); } + if (flush) + kvm_arch_flush_remote_tlbs_memslot(kvm, memslot); + if (copy_to_user(log->dirty_bitmap, dirty_bitmap_buffer, n)) return -EFAULT; return 0; } -EXPORT_SYMBOL_GPL(kvm_get_dirty_log_protect); + + +/** + * kvm_vm_ioctl_get_dirty_log - get and clear the log of dirty pages in a slot + * @kvm: kvm instance + * @log: slot id and address to which we copy the log + * + * Steps 1-4 below provide general overview of dirty page logging. See + * kvm_get_dirty_log_protect() function description for additional details. + * + * We call kvm_get_dirty_log_protect() to handle steps 1-3, upon return we + * always flush the TLB (step 4) even if previous step failed and the dirty + * bitmap may be corrupt. Regardless of previous outcome the KVM logging API + * does not preclude user space subsequent dirty log read. Flushing TLB ensures + * writes will be marked dirty for next log read. + * + * 1. Take a snapshot of the bit and clear it if needed. + * 2. Write protect the corresponding page. + * 3. Copy the snapshot to the userspace. + * 4. Flush TLB's if needed. + */ +static int kvm_vm_ioctl_get_dirty_log(struct kvm *kvm, + struct kvm_dirty_log *log) +{ + int r; + + mutex_lock(&kvm->slots_lock); + + r = kvm_get_dirty_log_protect(kvm, log); + + mutex_unlock(&kvm->slots_lock); + return r; +} /** * kvm_clear_dirty_log_protect - clear dirty bits in the bitmap * and reenable dirty page tracking for the corresponding pages. * @kvm: pointer to kvm instance * @log: slot id and address from which to fetch the bitmap of dirty pages - * @flush: true if TLB flush is needed by caller */ -int kvm_clear_dirty_log_protect(struct kvm *kvm, - struct kvm_clear_dirty_log *log, bool *flush) +static int kvm_clear_dirty_log_protect(struct kvm *kvm, + struct kvm_clear_dirty_log *log) { struct kvm_memslots *slots; struct kvm_memory_slot *memslot; @@ -1337,6 +1370,7 @@ int kvm_clear_dirty_log_protect(struct kvm *kvm, unsigned long i, n; unsigned long *dirty_bitmap; unsigned long *dirty_bitmap_buffer; + bool flush; as_id = log->slot >> 16; id = (u16)log->slot; @@ -1360,7 +1394,9 @@ int kvm_clear_dirty_log_protect(struct kvm *kvm, (log->num_pages < memslot->npages - log->first_page && (log->num_pages & 63))) return -EINVAL; - *flush = false; + kvm_arch_sync_dirty_log(kvm, memslot); + + flush = false; dirty_bitmap_buffer = kvm_second_dirty_bitmap(memslot); if (copy_from_user(dirty_bitmap_buffer, log->dirty_bitmap, n)) return -EFAULT; @@ -1383,17 +1419,32 @@ int kvm_clear_dirty_log_protect(struct kvm *kvm, * a problem if userspace sets them in log->dirty_bitmap. */ if (mask) { - *flush = true; + flush = true; kvm_arch_mmu_enable_log_dirty_pt_masked(kvm, memslot, offset, mask); } } spin_unlock(&kvm->mmu_lock); + if (flush) + kvm_arch_flush_remote_tlbs_memslot(kvm, memslot); + return 0; } -EXPORT_SYMBOL_GPL(kvm_clear_dirty_log_protect); -#endif + +static int kvm_vm_ioctl_clear_dirty_log(struct kvm *kvm, + struct kvm_clear_dirty_log *log) +{ + int r; + + mutex_lock(&kvm->slots_lock); + + r = kvm_clear_dirty_log_protect(kvm, log); + + mutex_unlock(&kvm->slots_lock); + return r; +} +#endif /* CONFIG_KVM_GENERIC_DIRTYLOG_READ_PROTECT */ bool kvm_largepages_enabled(void) { |