diff options
| -rw-r--r-- | drivers/virtio/virtio_mem.c | 116 |
1 files changed, 114 insertions, 2 deletions
diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c index 270ddeaec059..a3ec795be8be 100644 --- a/drivers/virtio/virtio_mem.c +++ b/drivers/virtio/virtio_mem.c @@ -123,7 +123,7 @@ struct virtio_mem { * * When this lock is held the pointers can't change, ONLINE and * OFFLINE blocks can't change the state and no subblocks will get - * plugged. + * plugged/unplugged. */ struct mutex hotplug_mutex; bool hotplug_active; @@ -280,6 +280,12 @@ static int virtio_mem_mb_state_prepare_next_mb(struct virtio_mem *vm) _mb_id++) \ if (virtio_mem_mb_get_state(_vm, _mb_id) == _state) +#define virtio_mem_for_each_mb_state_rev(_vm, _mb_id, _state) \ + for (_mb_id = _vm->next_mb_id - 1; \ + _mb_id >= _vm->first_mb_id && _vm->nb_mb_state[_state]; \ + _mb_id--) \ + if (virtio_mem_mb_get_state(_vm, _mb_id) == _state) + /* * Mark all selected subblocks plugged. * @@ -326,6 +332,19 @@ static bool virtio_mem_mb_test_sb_plugged(struct virtio_mem *vm, } /* + * Test if all selected subblocks are unplugged. + */ +static bool virtio_mem_mb_test_sb_unplugged(struct virtio_mem *vm, + unsigned long mb_id, int sb_id, + int count) +{ + const int bit = (mb_id - vm->first_mb_id) * vm->nb_sb_per_mb + sb_id; + + /* TODO: Helper similar to bitmap_set() */ + return find_next_bit(vm->sb_bitmap, bit + count, bit) >= bit + count; +} + +/* * Find the first plugged subblock. Returns vm->nb_sb_per_mb in case there is * none. */ @@ -513,6 +532,9 @@ static void virtio_mem_notify_offline(struct virtio_mem *vm, BUG(); break; } + + /* trigger the workqueue, maybe we can now unplug memory. */ + virtio_mem_retry(vm); } static void virtio_mem_notify_online(struct virtio_mem *vm, unsigned long mb_id, @@ -1123,6 +1145,94 @@ out_unlock: } /* + * Unplug the desired number of plugged subblocks of an offline memory block. + * Will fail if any subblock cannot get unplugged (instead of skipping it). + * + * Will modify the state of the memory block. Might temporarily drop the + * hotplug_mutex. + * + * Note: Can fail after some subblocks were successfully unplugged. + */ +static int virtio_mem_mb_unplug_any_sb_offline(struct virtio_mem *vm, + unsigned long mb_id, + uint64_t *nb_sb) +{ + int rc; + + rc = virtio_mem_mb_unplug_any_sb(vm, mb_id, nb_sb); + + /* some subblocks might have been unplugged even on failure */ + if (!virtio_mem_mb_test_sb_plugged(vm, mb_id, 0, vm->nb_sb_per_mb)) + virtio_mem_mb_set_state(vm, mb_id, + VIRTIO_MEM_MB_STATE_OFFLINE_PARTIAL); + if (rc) + return rc; + + if (virtio_mem_mb_test_sb_unplugged(vm, mb_id, 0, vm->nb_sb_per_mb)) { + /* + * Remove the block from Linux - this should never fail. + * Hinder the block from getting onlined by marking it + * unplugged. Temporarily drop the mutex, so + * any pending GOING_ONLINE requests can be serviced/rejected. + */ + virtio_mem_mb_set_state(vm, mb_id, + VIRTIO_MEM_MB_STATE_UNUSED); + + mutex_unlock(&vm->hotplug_mutex); + rc = virtio_mem_mb_remove(vm, mb_id); + BUG_ON(rc); + mutex_lock(&vm->hotplug_mutex); + } + return 0; +} + +/* + * Try to unplug the requested amount of memory. + */ +static int virtio_mem_unplug_request(struct virtio_mem *vm, uint64_t diff) +{ + uint64_t nb_sb = diff / vm->subblock_size; + unsigned long mb_id; + int rc; + + if (!nb_sb) + return 0; + + /* + * We'll drop the mutex a couple of times when it is safe to do so. + * This might result in some blocks switching the state (online/offline) + * and we could miss them in this run - we will retry again later. + */ + mutex_lock(&vm->hotplug_mutex); + + /* Try to unplug subblocks of partially plugged offline blocks. */ + virtio_mem_for_each_mb_state_rev(vm, mb_id, + VIRTIO_MEM_MB_STATE_OFFLINE_PARTIAL) { + rc = virtio_mem_mb_unplug_any_sb_offline(vm, mb_id, + &nb_sb); + if (rc || !nb_sb) + goto out_unlock; + cond_resched(); + } + + /* Try to unplug subblocks of plugged offline blocks. */ + virtio_mem_for_each_mb_state_rev(vm, mb_id, + VIRTIO_MEM_MB_STATE_OFFLINE) { + rc = virtio_mem_mb_unplug_any_sb_offline(vm, mb_id, + &nb_sb); + if (rc || !nb_sb) + goto out_unlock; + cond_resched(); + } + + mutex_unlock(&vm->hotplug_mutex); + return 0; +out_unlock: + mutex_unlock(&vm->hotplug_mutex); + return rc; +} + +/* * Try to unplug all blocks that couldn't be unplugged before, for example, * because the hypervisor was busy. */ @@ -1204,8 +1314,10 @@ retry: if (vm->requested_size > vm->plugged_size) { diff = vm->requested_size - vm->plugged_size; rc = virtio_mem_plug_request(vm, diff); + } else { + diff = vm->plugged_size - vm->requested_size; + rc = virtio_mem_unplug_request(vm, diff); } - /* TODO: try to unplug memory */ } switch (rc) { |