Re: [PATCH 1/5] ebpf: Added eBPF initialization by fds and map update.

From: Jason Wang <jasowang@redhat.com>
To: Andrew Melnychenko <andrew@daynix.com>,
	mst@redhat.com, yuri.benditovich@daynix.com, armbru@redhat.com,
	eblake@redhat.com, berrange@redhat.com
Cc: yan@daynix.com, qemu-devel@nongnu.org
Subject: Re: [PATCH 1/5] ebpf: Added eBPF initialization by fds and map update.
Date: Fri, 20 Aug 2021 11:34:06 +0800	[thread overview]
Message-ID: <0cb9e90f-0d9f-8b31-f459-578a8fa90c7e@redhat.com> (raw)
In-Reply-To: <20210713153758.323614-2-andrew@daynix.com>

在 2021/7/13 下午11:37, Andrew Melnychenko 写道:
> -static bool ebpf_rss_set_indirections_table(struct EBPFRSSContext *ctx,
> -                                            uint16_t *indirections_table,
> -                                            size_t len)
> -{
> -    uint32_t i = 0;
> +    ctx->program_fd = program_fd;
> +    ctx->map_configuration = config_fd;
>   
> -    if (!ebpf_rss_is_loaded(ctx) || indirections_table == NULL ||
> -       len > VIRTIO_NET_RSS_MAX_TABLE_LEN) {
> +    ctx->mmap_configuration = mmap(NULL, qemu_real_host_page_size,
> +                                   PROT_READ | PROT_WRITE, MAP_SHARED,
> +                                   ctx->map_configuration, 0);
> +    if (ctx->mmap_configuration == MAP_FAILED) {
> +        trace_ebpf_error("eBPF RSS", "can not mmap eBPF configuration array");
>           return false;
>       }
>   
> -    for (; i < len; ++i) {
> -        if (bpf_map_update_elem(ctx->map_indirections_table, &i,
> -                                indirections_table + i, 0) < 0) {
> -            return false;
> -        }
> -    }
> -    return true;
> -}
> -

It looks to me you want to drop syscall path for map updating 
completely. I think we'd better keep that for backward compatibility?

Thanks