From patchwork Wed May 5 20:38:55 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Steven Rostedt X-Patchwork-Id: 12240993 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3AE81C43460 for ; Wed, 5 May 2021 20:39:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1F3E3613EA for ; Wed, 5 May 2021 20:39:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234968AbhEEUkD (ORCPT ); Wed, 5 May 2021 16:40:03 -0400 Received: from mail.kernel.org ([198.145.29.99]:46990 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234675AbhEEUkC (ORCPT ); Wed, 5 May 2021 16:40:02 -0400 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 37678613E3; Wed, 5 May 2021 20:39:04 +0000 (UTC) Date: Wed, 5 May 2021 16:38:55 -0400 From: Steven Rostedt To: LKML Cc: Stefan Hajnoczi , Stefano Garzarella , "Michael S. Tsirkin" , Jason Wang , "David S. Miller" , Jakub Kicinski , kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, Joel Fernandes , Linux Trace Devel Subject: [RFC][PATCH] vhost/vsock: Add vsock_list file to map cid with vhost tasks Message-ID: <20210505163855.32dad8e7@gandalf.local.home> X-Mailer: Claws Mail 3.17.8 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org The new trace-cmd 3.0 (which is almost ready to be released) allows for tracing between host and guests with timestamp synchronization such that the events on the host and the guest can be interleaved in the proper order that they occur. KernelShark now has a plugin that visualizes this interaction. The implementation requires that the guest has a vsock CID assigned, and on the guest a "trace-cmd agent" is running, that will listen on a port for the CID. The on the host a "trace-cmd record -A guest@cid:port -e events" can be called and the host will connect to the guest agent through the cid/port pair and have the agent enable tracing on behalf of the host and send the trace data back down to it. The problem is that there is no sure fire way to find the CID for a guest. Currently, the user must know the cid, or we have a hack that looks for the qemu process and parses the --guest-cid parameter from it. But this is prone to error and does not work on other implementation (was told that crosvm does not use qemu). As I can not find a way to discover CIDs assigned to guests via any kernel interface, I decided to create this one. Note, I'm not attached to it. If there's a better way to do this, I would love to have it. But since I'm not an expert in the networking layer nor virtio, I decided to stick to what I know and add a debugfs interface that simply lists all the registered CIDs and the worker task that they are associated with. The worker task at least has the PID of the task it represents. Now I can find the cid / host process in charge of the guest pair: # cat /sys/kernel/debug/vsock_list 3 vhost-1954:2002 # ps aux | grep 1954 qemu 1954 9.9 21.3 1629092 796148 ? Sl 16:22 0:58 /usr/bin/qemu-kvm -name guest=Fedora21,debug-threads=on -S -object secret,id=masterKey0,format=raw,file=/var/lib/libvirt/qemu/domain-1-Fedora21/master-key.aes -machine pc-1.2,accel=kvm,usb=off,dump-guest-core=off -cpu qemu64 -m 1000 -overcommit mem-lock=off -smp 2,sockets=2,cores=1,threads=1 -uuid 1eefeeb0-3ac7-07c1-926e-236908313b4c -no-user-config -nodefaults -chardev socket,id=charmonitor,fd=32,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc -no-shutdown -boot strict=on -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x6 -blockdev {"driver":"host_device","filename":"/dev/mapper/vg_bxtest-GuestFedora","node-name":"libvirt-1-storage","auto-read-only":true,"discard":"unmap"} -blockdev {"node-name":"libvirt-1-format","read-only":false,"driver":"raw","file":"libvirt-1-storage"} -device ide-hd,bus=ide.0,unit=0,drive=libvirt-1- format,id=ide0-0-0,bootindex=1 -netdev tap,fd=34,id=hostnet0 -device rtl8139,netdev=hostnet0,id=net0,mac=52:54:00:9f:e9:d5,bus=pci.0,addr=0x3 -netdev tap,fd=35,id=hostnet1 -device virtio-net-pci,netdev=hostnet1,id=net1,mac=52:54:00:ec:dc:6e,bus=pci.0,addr=0x5 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -chardev pipe,id=charchannel0,path=/var/lib/trace-cmd/virt/Fedora21/trace-pipe-cpu0 -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=trace-pipe-cpu0 -chardev pipe,id=charchannel1,path=/var/lib/trace-cmd/virt/Fedora21/trace-pipe-cpu1 -device virtserialport,bus=virtio-serial0.0,nr=2,chardev=charchannel1,id=channel1,name=trace-pipe-cpu1 -vnc 127.0.0.1:0 -device cirrus-vga,id=video0,bus=pci.0,addr=0x2 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x4 -sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny -device vhost-vsock-pci,id=vsock0,guest-cid=3,vhostfd=16,bus=pci.0,addr=0x7 -msg timestamp=on root 2000 0.0 0.0 0 0 ? S 16:22 0:00 [kvm-pit/1954] root 2002 0.0 0.0 0 0 ? S 16:22 0:00 [vhost-1954] This is just an example of what I'm looking for. Just a way to find what process is using what cid. Signed-off-by: Steven Rostedt (VMware) diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c index 5e78fb719602..4f03b25b23c1 100644 --- a/drivers/vhost/vsock.c +++ b/drivers/vhost/vsock.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include "vhost.h" @@ -900,6 +901,128 @@ static struct miscdevice vhost_vsock_misc = { .fops = &vhost_vsock_fops, }; +static struct dentry *vsock_file; + +struct vsock_file_iter { + struct hlist_node *node; + int index; +}; + + +static void *vsock_next(struct seq_file *m, void *v, loff_t *pos) +{ + struct vsock_file_iter *iter = v; + struct vhost_vsock *vsock; + + if (pos) + (*pos)++; + + if (iter->index >= (int)HASH_SIZE(vhost_vsock_hash)) + return NULL; + + if (iter->node) + iter->node = rcu_dereference_raw(hlist_next_rcu(iter->node)); + + for (;;) { + if (iter->node) { + vsock = hlist_entry_safe(rcu_dereference_raw(iter->node), + struct vhost_vsock, hash); + if (vsock->guest_cid) + break; + iter->node = rcu_dereference_raw(hlist_next_rcu(iter->node)); + continue; + } + iter->index++; + if (iter->index >= HASH_SIZE(vhost_vsock_hash)) + return NULL; + + iter->node = rcu_dereference_raw(hlist_first_rcu(&vhost_vsock_hash[iter->index])); + } + return iter; +} + +static void *vsock_start(struct seq_file *m, loff_t *pos) +{ + struct vsock_file_iter *iter = m->private; + loff_t l = 0; + void *t; + + rcu_read_lock(); + + iter->index = -1; + iter->node = NULL; + t = vsock_next(m, iter, NULL); + + for (; iter->index < HASH_SIZE(vhost_vsock_hash) && l < *pos; + t = vsock_next(m, iter, &l)) + ; + + return t; +} + +static void vsock_stop(struct seq_file *m, void *p) +{ + rcu_read_unlock(); +} + +static int vsock_show(struct seq_file *m, void *v) +{ + struct vsock_file_iter *iter = v; + struct vhost_vsock *vsock; + struct task_struct *worker; + + if (!iter || iter->index >= HASH_SIZE(vhost_vsock_hash)) + return 0; + + vsock = hlist_entry_safe(rcu_dereference_raw(iter->node), struct vhost_vsock, hash); + worker = vsock->dev.worker; + seq_printf(m, "%d\t", vsock->guest_cid); + + if (worker) + seq_printf(m, "%s:%d\n", worker->comm, worker->pid); + else + seq_puts(m, "(no task)\n"); + + return 0; +} + +static const struct seq_operations vsock_file_seq_ops = { + .start = vsock_start, + .next = vsock_next, + .stop = vsock_stop, + .show = vsock_show, +}; + +static int vsock_file_open(struct inode *inode, struct file *file) +{ + struct vsock_file_iter *iter; + struct seq_file *m; + int ret; + + iter = kzalloc(sizeof(*iter), GFP_KERNEL); + if (!iter) + return -ENOMEM; + + ret = seq_open(file, &vsock_file_seq_ops); + if (ret) { + kfree(iter); + return ret; + } + + m = file->private_data; + m->private = iter; + + return 0; +} + +static const struct file_operations vsock_file_fops = { + .owner = THIS_MODULE, + .open = vsock_file_open, + .release = seq_release_private, + .read = seq_read, + .llseek = seq_lseek, +}; + static int __init vhost_vsock_init(void) { int ret; @@ -908,12 +1031,15 @@ static int __init vhost_vsock_init(void) VSOCK_TRANSPORT_F_H2G); if (ret < 0) return ret; + vsock_file = debugfs_create_file("vsock_list", 0400, + NULL, NULL, &vsock_file_fops); return misc_register(&vhost_vsock_misc); }; static void __exit vhost_vsock_exit(void) { misc_deregister(&vhost_vsock_misc); + debugfs_remove(vsock_file); vsock_core_unregister(&vhost_transport.transport); };