[dpdk-stable] [PATCH 3/3] net/virtio-user: fix memory hotplug support in vhost-kernel

[Burakov, Anatoly]

On 05-Sep-18 5:28 AM, Tiwei Bie wrote:
> It's possible to have much more hugepage backed memory regions
> than what vhost-kernel supports due to the memory hotplug, which
> may cause problems. A better solution is to have the virtio-user
> pass all the memory ranges reserved by DPDK to vhost-kernel.
> 
> Fixes: 12ecb2f63b12 ("net/virtio-user: support memory hotplug")
> Cc: stable at dpdk.org
> 
> Signed-off-by: Tiwei Bie <tiwei.bie at intel.com>
> ---
>   drivers/net/virtio/virtio_user/vhost_kernel.c | 38 +++++++++----------
>   1 file changed, 18 insertions(+), 20 deletions(-)
> 
> diff --git a/drivers/net/virtio/virtio_user/vhost_kernel.c b/drivers/net/virtio/virtio_user/vhost_kernel.c
> index 897fee0af..9338166d9 100644
> --- a/drivers/net/virtio/virtio_user/vhost_kernel.c
> +++ b/drivers/net/virtio/virtio_user/vhost_kernel.c
> @@ -70,41 +70,41 @@ static uint64_t vhost_req_user_to_kernel[] = {
>   	[VHOST_USER_SET_MEM_TABLE] = VHOST_SET_MEM_TABLE,
>   };
>   
> -struct walk_arg {
> -	struct vhost_memory_kernel *vm;
> -	uint32_t region_nr;
> -};
>   static int
> -add_memory_region(const struct rte_memseg_list *msl __rte_unused,
> -		const struct rte_memseg *ms, size_t len, void *arg)
> +add_memseg_list(const struct rte_memseg_list *msl, void *arg)
>   {
> -	struct walk_arg *wa = arg;
> +	struct vhost_memory_kernel *vm = arg;
>   	struct vhost_memory_region *mr;
>   	void *start_addr;
> +	uint64_t len;
>   
> -	if (wa->region_nr >= max_regions)
> +	if (vm->nregions >= max_regions)
>   		return -1;
>   
> -	mr = &wa->vm->regions[wa->region_nr++];
> -	start_addr = ms->addr;
> +	start_addr = msl->base_va;
> +	len = msl->page_sz * msl->memseg_arr.len;
> +
> +	mr = &vm->regions[vm->nregions++];
>   
>   	mr->guest_phys_addr = (uint64_t)(uintptr_t)start_addr;
>   	mr->userspace_addr = (uint64_t)(uintptr_t)start_addr;
>   	mr->memory_size = len;
> -	mr->mmap_offset = 0;
> +	mr->mmap_offset = 0; /* flags_padding */
> +
> +	PMD_DRV_LOG(DEBUG, "index=%u addr=%p len=%" PRIu64,
> +			vm->nregions - 1, start_addr, len);
>   
>   	return 0;
>   }
>   
> -/* By default, vhost kernel module allows 64 regions, but DPDK allows
> - * 256 segments. As a relief, below function merges those virtually
> - * adjacent memsegs into one region.
> +/* By default, vhost kernel module allows 64 regions, but DPDK may
> + * have much more memory regions. Below function will treat each
> + * contiguous memory space reserved by DPDK as one region.
>    */
>   static struct vhost_memory_kernel *
>   prepare_vhost_memory_kernel(void)
>   {
>   	struct vhost_memory_kernel *vm;
> -	struct walk_arg wa;
>   
>   	vm = malloc(sizeof(struct vhost_memory_kernel) +
>   			max_regions *
> @@ -112,20 +112,18 @@ prepare_vhost_memory_kernel(void)
>   	if (!vm)
>   		return NULL;
>   
> -	wa.region_nr = 0;
> -	wa.vm = vm;
> +	vm->nregions = 0;
> +	vm->padding = 0;
>   
>   	/*
>   	 * The memory lock has already been taken by memory subsystem
>   	 * or virtio_user_start_device().
>   	 */
> -	if (rte_memseg_contig_walk_thread_unsafe(add_memory_region, &wa) < 0) {
> +	if (rte_memseg_list_walk_thread_unsafe(add_memseg_list, vm) < 0) {
>   		free(vm);
>   		return NULL;
>   	}
>   
> -	vm->nregions = wa.region_nr;
> -	vm->padding = 0;
>   	return vm;
>   }
>   
> 

Doesn't that assume single file segments mode?

-- 
Thanks,
Anatoly