On Thu, 16 Feb 2023 12:47:52 +0100
David Hildenbrand <da...@redhat.com> wrote:
> Checking whether the memory regions are equal is sufficient: if they are
> equal, then most certainly the contained fd is equal.
sounds reasonable to me.
>
> The whole vhost-user memslot handling is suboptimal and overly
> complicated. We shouldn't have to lookup a RAM memory regions we got
> notified about in vhost_user_get_mr_data() using a host pointer. But that
While on janitor duty can you fixup following?
vhost_user_get_mr_data() -> memory_region_from_host ->
-> qemu_ram_block_from_host()
for qemu_ram_block_from_host doc comment seems to out of
sync (ram_addr not longer exists)
> requires a bigger rework -- especially an alternative vhost_set_mem_table()
> backend call that simply consumes MemoryRegionSections.
just skimming through usage of vhost_user_get_mr_data() it looks like
we are first collecting MemoryRegionSection-s into tmp_sections
then we do vhost_commit we convert then into vhost_memory_region list
and the we are trying hard to convert addresses from the later
to back to MemoryRegions we've lost during tmp_sections conversion
all over the place.
To me it looks like we should drop conversion to vhost_dev::mem
and replace its usage with vhost_dev::mem_sections directly
to get rid of data duplication and back and forth addr<->mr conversion.
> For now, let's just drop vhost_backend_can_merge().
>
> Signed-off-by: David Hildenbrand <da...@redhat.com>
Reviewed-by: Igor Mammedov <imamm...@redhat.com>
> ---
> hw/virtio/vhost-user.c | 14 --------------
> hw/virtio/vhost-vdpa.c | 1 -
> hw/virtio/vhost.c | 6 +-----
> include/hw/virtio/vhost-backend.h | 4 ----
> 4 files changed, 1 insertion(+), 24 deletions(-)
>
> diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
> index e68daa35d4..4bfaf559a7 100644
> --- a/hw/virtio/vhost-user.c
> +++ b/hw/virtio/vhost-user.c
> @@ -2195,19 +2195,6 @@ static int vhost_user_migration_done(struct vhost_dev
> *dev, char* mac_addr)
> return -ENOTSUP;
> }
>
> -static bool vhost_user_can_merge(struct vhost_dev *dev,
> - uint64_t start1, uint64_t size1,
> - uint64_t start2, uint64_t size2)
> -{
> - ram_addr_t offset;
> - int mfd, rfd;
> -
> - (void)vhost_user_get_mr_data(start1, &offset, &mfd);
> - (void)vhost_user_get_mr_data(start2, &offset, &rfd);
> -
> - return mfd == rfd;
> -}
> -
> static int vhost_user_net_set_mtu(struct vhost_dev *dev, uint16_t mtu)
> {
> VhostUserMsg msg;
> @@ -2704,7 +2691,6 @@ const VhostOps user_ops = {
> .vhost_set_vring_enable = vhost_user_set_vring_enable,
> .vhost_requires_shm_log = vhost_user_requires_shm_log,
> .vhost_migration_done = vhost_user_migration_done,
> - .vhost_backend_can_merge = vhost_user_can_merge,
> .vhost_net_set_mtu = vhost_user_net_set_mtu,
> .vhost_set_iotlb_callback = vhost_user_set_iotlb_callback,
> .vhost_send_device_iotlb_msg = vhost_user_send_device_iotlb_msg,
> diff --git a/hw/virtio/vhost-vdpa.c b/hw/virtio/vhost-vdpa.c
> index 542e003101..9ab7bc8718 100644
> --- a/hw/virtio/vhost-vdpa.c
> +++ b/hw/virtio/vhost-vdpa.c
> @@ -1317,7 +1317,6 @@ const VhostOps vdpa_ops = {
> .vhost_set_config = vhost_vdpa_set_config,
> .vhost_requires_shm_log = NULL,
> .vhost_migration_done = NULL,
> - .vhost_backend_can_merge = NULL,
> .vhost_net_set_mtu = NULL,
> .vhost_set_iotlb_callback = NULL,
> .vhost_send_device_iotlb_msg = NULL,
> diff --git a/hw/virtio/vhost.c b/hw/virtio/vhost.c
> index b7fb960fa9..9d8662aa98 100644
> --- a/hw/virtio/vhost.c
> +++ b/hw/virtio/vhost.c
> @@ -733,11 +733,7 @@ static void vhost_region_add_section(struct vhost_dev
> *dev,
> size_t offset = mrs_gpa - prev_gpa_start;
>
> if (prev_host_start + offset == mrs_host &&
> - section->mr == prev_sec->mr &&
> - (!dev->vhost_ops->vhost_backend_can_merge ||
> - dev->vhost_ops->vhost_backend_can_merge(dev,
> - mrs_host, mrs_size,
> - prev_host_start, prev_size))) {
> + section->mr == prev_sec->mr) {
> uint64_t max_end = MAX(prev_host_end, mrs_host + mrs_size);
> need_add = false;
> prev_sec->offset_within_address_space =
> diff --git a/include/hw/virtio/vhost-backend.h
> b/include/hw/virtio/vhost-backend.h
> index c5ab49051e..abf1601ba2 100644
> --- a/include/hw/virtio/vhost-backend.h
> +++ b/include/hw/virtio/vhost-backend.h
> @@ -86,9 +86,6 @@ typedef int (*vhost_set_vring_enable_op)(struct vhost_dev
> *dev,
> typedef bool (*vhost_requires_shm_log_op)(struct vhost_dev *dev);
> typedef int (*vhost_migration_done_op)(struct vhost_dev *dev,
> char *mac_addr);
> -typedef bool (*vhost_backend_can_merge_op)(struct vhost_dev *dev,
> - uint64_t start1, uint64_t size1,
> - uint64_t start2, uint64_t size2);
> typedef int (*vhost_vsock_set_guest_cid_op)(struct vhost_dev *dev,
> uint64_t guest_cid);
> typedef int (*vhost_vsock_set_running_op)(struct vhost_dev *dev, int start);
> @@ -160,7 +157,6 @@ typedef struct VhostOps {
> vhost_set_vring_enable_op vhost_set_vring_enable;
> vhost_requires_shm_log_op vhost_requires_shm_log;
> vhost_migration_done_op vhost_migration_done;
> - vhost_backend_can_merge_op vhost_backend_can_merge;
> vhost_vsock_set_guest_cid_op vhost_vsock_set_guest_cid;
> vhost_vsock_set_running_op vhost_vsock_set_running;
> vhost_set_iotlb_callback_op vhost_set_iotlb_callback;
