Messages in this thread | | | Date | Thu, 15 Oct 2020 16:28:08 +0800 | From | Wei Yang <> | Subject | Re: [PATCH v1 05/29] virtio-mem: generalize check for added memory |
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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@redhat.com> >Cc: Jason Wang <jasowang@redhat.com> >Cc: Pankaj Gupta <pankaj.gupta.linux@gmail.com> >Signed-off-by: David Hildenbrand <david@redhat.com> >--- > 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
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