[dpdk-dev] [PATCH v2 5/7] net/virtio_user: add vhost kernel support
Yuanhan Liu
yuanhan.liu at linux.intel.com
Mon Dec 26 08:44:37 CET 2016
On Fri, Dec 23, 2016 at 07:14:24AM +0000, Jianfeng Tan wrote:
> + * Copyright(c) 2010-2016 Intel Corporation. All rights reserved.
^^^^^^^^^
I think it should be 2016.
> +/* 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.
> + */
> +static struct vhost_memory_kernel *
> +prepare_vhost_memory_kernel(void)
> +{
> + uint32_t i, j, k = 0;
> + struct rte_memseg *seg;
> + struct vhost_memory_region *mr;
> + struct vhost_memory_kernel *vm;
> +
> + vm = malloc(sizeof(struct vhost_memory_kernel) +
> + VHOST_KERNEL_MAX_REGIONS *
> + sizeof(struct vhost_memory_region));
> +
> + for (i = 0; i < RTE_MAX_MEMSEG; ++i) {
> + seg = &rte_eal_get_configuration()->mem_config->memseg[i];
> + if (!seg->addr)
> + break;
> +
> + int new_region = 1;
> +
> + for (j = 0; j < k; ++j) {
> + mr = &vm->regions[j];
> +
> + if (mr->userspace_addr + mr->memory_size ==
> + (uint64_t)seg->addr) {
> + mr->memory_size += seg->len;
> + new_region = 0;
> + break;
> + }
> +
> + if ((uint64_t)seg->addr + seg->len ==
> + mr->userspace_addr) {
> + mr->guest_phys_addr = (uint64_t)seg->addr;
Be careful, such cast would break 32 bit OS build.
> +static int
> +vhost_kernel_ioctl(struct virtio_user_dev *dev,
> + enum vhost_user_request req,
> + void *arg)
> +{
> + int i, ret = -1;
> + uint64_t req_kernel;
> + struct vhost_memory_kernel *vm = NULL;
> +
> + req_kernel = vhost_req_user_to_kernel[req];
> +
> + if (req_kernel == VHOST_SET_MEM_TABLE) {
> + vm = prepare_vhost_memory_kernel();
> + if (!vm)
> + return -1;
> + arg = (void *)vm;
> + }
> +
> + /* Does not work when VIRTIO_F_IOMMU_PLATFORM now, why? */
Because this feature need the vhost IOTLB support from the device
emulation. Patches for QEMU hasn't been merged yet, but it has been
there for a while.
Since we don't have the support yet, for sure it won't work. But
I'm wondering why you have to disable it explicitly?
> + if (req_kernel == VHOST_SET_FEATURES)
> + *(uint64_t *)arg &= ~(1ULL << VIRTIO_F_IOMMU_PLATFORM);
> +
> + for (i = 0; i < VHOST_KERNEL_MAX_QUEUES; ++i) {
> + if (dev->vhostfds[i] < 0)
> + continue;
> +
> + ret = ioctl(dev->vhostfds[i], req_kernel, arg);
> + if (ret < 0)
> + break;
> + }
> +
> + if (vm)
> + free(vm);
> +
> + return ret;
> +}
> +
> +/**
> + * Set up environment to talk with a vhost kernel backend.
> + *
> + * @return
> + * - (-1) if fail to set up;
> + * - (>=0) if successful.
> + */
> +static int
> +vhost_kernel_setup(struct virtio_user_dev *dev)
> +{
> + int vhostfd;
> + uint32_t q;
Why not simply use 'i'?
> +static int
> +vhost_kernel_enable_queue_pair(struct virtio_user_dev *dev,
> + uint16_t pair_idx,
> + int enable)
> +{
> + unsigned int features;
Better to rename it to "tap_features" or something? When I first saw
such name, I thought it was about vhost features.
--yliu
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