On Mon, Oct 12, 2020 at 02:52:59PM +0200, David Hildenbrand wrote:
>Let's check by traversing busy system RAM resources instead, to avoid
>relying on memory block states.
>
>Don't use walk_system_ram_range(), as that works on pages and we want to
>use the bare addresses we have easily at hand.
>
>Cc: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
>Cc: Jason Wang <jasowang@xxxxxxxxxx>
>Cc: Pankaj Gupta <pankaj.gupta.linux@xxxxxxxxx>
>Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
>---
> drivers/virtio/virtio_mem.c | 19 +++++++++++++++----
> 1 file changed, 15 insertions(+), 4 deletions(-)
>
>diff --git a/drivers/virtio/virtio_mem.c b/drivers/virtio/virtio_mem.c
>index b3eebac7191f..6bbd1cfd10d3 100644
>--- a/drivers/virtio/virtio_mem.c
>+++ b/drivers/virtio/virtio_mem.c
>@@ -1749,6 +1749,20 @@ static void virtio_mem_delete_resource(struct virtio_mem *vm)
> vm->parent_resource = NULL;
> }
>
>+static int virtio_mem_range_has_system_ram(struct resource *res, void *arg)
>+{
>+ return 1;
>+}
>+
>+static bool virtio_mem_has_memory_added(struct virtio_mem *vm)
>+{
>+ const unsigned long flags = IORESOURCE_SYSTEM_RAM | IORESOURCE_BUSY;
>+
>+ return walk_iomem_res_desc(IORES_DESC_NONE, flags, vm->addr,
>+ vm->addr + vm->region_size, NULL,
>+ virtio_mem_range_has_system_ram) == 1;
>+}
>+
> static int virtio_mem_probe(struct virtio_device *vdev)
> {
> struct virtio_mem *vm;
>@@ -1870,10 +1884,7 @@ static void virtio_mem_remove(struct virtio_device *vdev)
> * the system. And there is no way to stop the driver/device from going
> * away. Warn at least.
> */
>- if (vm->nb_mb_state[VIRTIO_MEM_MB_STATE_OFFLINE] ||
>- vm->nb_mb_state[VIRTIO_MEM_MB_STATE_OFFLINE_PARTIAL] ||
>- vm->nb_mb_state[VIRTIO_MEM_MB_STATE_ONLINE] ||
>- vm->nb_mb_state[VIRTIO_MEM_MB_STATE_ONLINE_PARTIAL]) {
>+ if (virtio_mem_has_memory_added(vm)) {
I am not sure this would be more efficient.
> dev_warn(&vdev->dev, "device still has system memory added\n");
> } else {
> virtio_mem_delete_resource(vm);
BTW, I got one question during review.
Per my understanding, there are 4 states of a virtio memory block
* OFFLINE[_PARTIAL]
* ONLINE[_PARTIAL]
While, if my understanding is correct, those two offline states are transient.
If the required range is onlined, the state would be change to
ONLINE[_PARTIAL] respectively. If it is not, the state is reverted to UNUSED
or PLUGGED.
What I am lost is why you do virtio_mem_mb_remove() on OFFLINE_PARTIAL memory
block? Since we wait for the workqueue finish its job.
Also, during virtio_mem_remove(), we just handle OFFLINE_PARTIAL memory block.
How about memory block in other states? It is not necessary to remove
ONLINE[_PARTIAL] memroy blocks?
Thanks in advance, since I may missed some concepts.
>--
>2.26.2
--
Wei Yang
Help you, Help me
