From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752162AbdGDJ1u (ORCPT ); Tue, 4 Jul 2017 05:27:50 -0400 Received: from mx1.redhat.com ([209.132.183.28]:40848 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751631AbdGDJ1s (ORCPT ); Tue, 4 Jul 2017 05:27:48 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 71C5A40F1C Authentication-Results: ext-mx06.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx06.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=pbonzini@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 71C5A40F1C Subject: Re: [PATCH v1 1/1] KVM: trigger uevents when starting or stopping a VM To: Christian Borntraeger , Claudio Imbrenda , kvm@vger.kernel.org Cc: linux-kernel@vger.kernel.org References: <1499159018-19782-1-git-send-email-imbrenda@linux.vnet.ibm.com> <8d239a6c-3625-6964-7fd2-b753f2e15bf5@redhat.com> <3de04174-46d3-8741-2088-218b48ad20be@de.ibm.com> From: Paolo Bonzini Message-ID: Date: Tue, 4 Jul 2017 11:27:44 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.0 MIME-Version: 1.0 In-Reply-To: <3de04174-46d3-8741-2088-218b48ad20be@de.ibm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.30]); Tue, 04 Jul 2017 09:27:47 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/07/2017 11:25, Christian Borntraeger wrote: > On 07/04/2017 11:23 AM, Paolo Bonzini wrote: >> >> >> On 04/07/2017 11:03, Claudio Imbrenda wrote: >>> This patch adds a few lines to the KVM common code to fire a >>> KOBJ_CHANGE uevent whenever a KVM VM is created or destroyed. The event >>> carries two environment variables: >>> KVM_VM_CREATED which indicates how many times a new VM has been created, >>> KVM_VM_COUNT which indicates how many VMs are currently active. >> >> I'm not sure why KVM_VM_CREATED is useful, KVM_VM_COUNT can be a bit >> more interesting though not much. > > I am certainly interested in an trigger from "kvm was never used" to "kvm was used", > so having something like KVM_VM_CREATED has a value for me. Fair enough, that's a good use. Please add it to the commit message, however. Paolo >> But since we are at it, let's also add a PID. That one is the really >> useful one, because it gives you something to look at in debugfs. >> Another possibility is to add the debugfs directory name directly >> (KVM_VM_STATS_PATH or something like that). >> >> Paolo >> >>> Specific udev rules can be then set up in userspace to deal with the >>> creation or destruction of VMs as needed. >>> >>> Signed-off-by: Claudio Imbrenda >>> --- >>> virt/kvm/kvm_main.c | 25 +++++++++++++++++++++++++ >>> 1 file changed, 25 insertions(+) >>> >>> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c >>> index 6e3b12c..f67aa59 100644 >>> --- a/virt/kvm/kvm_main.c >>> +++ b/virt/kvm/kvm_main.c >>> @@ -130,6 +130,10 @@ EXPORT_SYMBOL_GPL(kvm_rebooting); >>> >>> static bool largepages_enabled = true; >>> >>> +static void kvm_uevent_notify_change(u64 created, u64 active); >>> +static u64 kvm_createvm_count; >>> +static u64 kvm_active_vms; >>> + >>> bool kvm_is_reserved_pfn(kvm_pfn_t pfn) >>> { >>> if (pfn_valid(pfn)) >>> @@ -627,6 +631,7 @@ static struct kvm *kvm_create_vm(unsigned long type) >>> { >>> int r, i; >>> struct kvm *kvm = kvm_arch_alloc_vm(); >>> + u64 activevms, createdvms; >>> >>> if (!kvm) >>> return ERR_PTR(-ENOMEM); >>> @@ -686,9 +691,12 @@ static struct kvm *kvm_create_vm(unsigned long type) >>> >>> spin_lock(&kvm_lock); >>> list_add(&kvm->vm_list, &vm_list); >>> + createdvms = ++kvm_createvm_count; >>> + activevms = ++kvm_active_vms; >>> spin_unlock(&kvm_lock); >>> >>> preempt_notifier_inc(); >>> + kvm_uevent_notify_change(createdvms, activevms); >>> >>> return kvm; >>> >>> @@ -739,11 +747,14 @@ static void kvm_destroy_vm(struct kvm *kvm) >>> { >>> int i; >>> struct mm_struct *mm = kvm->mm; >>> + u64 activevms, createdvms; >>> >>> kvm_destroy_vm_debugfs(kvm); >>> kvm_arch_sync_events(kvm); >>> spin_lock(&kvm_lock); >>> list_del(&kvm->vm_list); >>> + activevms = --kvm_active_vms; >>> + createdvms = kvm_createvm_count; >>> spin_unlock(&kvm_lock); >>> kvm_free_irq_routing(kvm); >>> for (i = 0; i < KVM_NR_BUSES; i++) { >>> @@ -767,6 +778,7 @@ static void kvm_destroy_vm(struct kvm *kvm) >>> preempt_notifier_dec(); >>> hardware_disable_all(); >>> mmdrop(mm); >>> + kvm_uevent_notify_change(createdvms, activevms); >>> } >>> >>> void kvm_get_kvm(struct kvm *kvm) >>> @@ -3864,6 +3876,19 @@ static const struct file_operations *stat_fops[] = { >>> [KVM_STAT_VM] = &vm_stat_fops, >>> }; >>> >>> +static void kvm_uevent_notify_change(u64 created, u64 active) >>> +{ >>> + char createvm_buf[40]; >>> + char activevm_buf[40]; >>> + char *ptr[3] = {createvm_buf, activevm_buf, NULL}; >>> + >>> + if (!kvm_dev.this_device) >>> + return; >>> + snprintf(createvm_buf, 40, "KVM_VM_CREATED=%llu", created); >>> + snprintf(activevm_buf, 40, "KVM_VM_ACTIVE=%llu", active); >>> + kobject_uevent_env(&kvm_dev.this_device->kobj, KOBJ_CHANGE, ptr); >>> +} >>> + >>> static int kvm_init_debug(void) >>> { >>> int r = -EEXIST; >>> >> >