On 06/07/2017 12:48, 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 four environment variables: > > KVM_VM_CREATED indicates how many times a new VM has been created. It > is useful for example to trigger specific actions when > the first VM is started > KVM_VM_COUNT indicates how many VMs are currently active. This can be > used for logging or monitoring purposes > KVM_VM_PID has the pid of the KVM process that has been started or > stopped. This can be used to perform process-specific > tuning. > KVM_VM_STATS_PATH contains the path in /sys to the directory with all > the runtime statistics for this VM. This is useful > for performance monitoring and profiling. > > 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 <[email protected]> > --- > virt/kvm/kvm_main.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 50 insertions(+) > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 6e3b12c..f4cf7d2 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -130,6 +130,12 @@ EXPORT_SYMBOL_GPL(kvm_rebooting); > > static bool largepages_enabled = true; > > +#define KVM_EVENT_CREATE_VM 0 > +#define KVM_EVENT_DESTROY_VM 1 > +static void kvm_uevent_notify_change(unsigned int type, struct kvm *kvm); > +static unsigned long long kvm_createvm_count; > +static unsigned long long kvm_active_vms; > + > bool kvm_is_reserved_pfn(kvm_pfn_t pfn) > { > if (pfn_valid(pfn)) > @@ -740,6 +746,7 @@ static void kvm_destroy_vm(struct kvm *kvm) > int i; > struct mm_struct *mm = kvm->mm; > > + kvm_uevent_notify_change(KVM_EVENT_DESTROY_VM, kvm); > kvm_destroy_vm_debugfs(kvm); > kvm_arch_sync_events(kvm); > spin_lock(&kvm_lock); > @@ -3212,6 +3219,7 @@ static int kvm_dev_ioctl_create_vm(unsigned long type) > fput(file); > return -ENOMEM; > } > + kvm_uevent_notify_change(KVM_EVENT_CREATE_VM, kvm); > > fd_install(r, file); > return r; > @@ -3864,6 +3872,48 @@ static const struct file_operations *stat_fops[] = { > [KVM_STAT_VM] = &vm_stat_fops, > }; > > +static void kvm_uevent_notify_change(unsigned int type, struct kvm *kvm) > +{ > + char cbuf[40], abuf[40], pidbuf[40], pathvar[18] = "KVM_VM_STATS_PATH="; > + char *ptr[5] = {cbuf, abuf, pidbuf, NULL, NULL}; > + char *tmp, *pathbuf; > + unsigned long long created, active; > + > + if (!kvm_dev.this_device || !kvm || !kvm->debugfs_dentry) > + return; > + > + spin_lock(&kvm_lock); > + if (type == KVM_EVENT_CREATE_VM) { > + kvm_createvm_count++; > + kvm_active_vms++; > + } else if (type == KVM_EVENT_DESTROY_VM) { > + kvm_active_vms--; > + } > + created = kvm_createvm_count; > + active = kvm_active_vms; > + spin_unlock(&kvm_lock); > + > + pathbuf = kmalloc(PATH_MAX, GFP_KERNEL); > + if (pathbuf) { > + tmp = dentry_path_raw(kvm->debugfs_dentry, > + pathbuf + sizeof(pathvar), > + PATH_MAX - sizeof(pathvar)); > + if (!IS_ERR(tmp)) { > + memcpy(tmp - sizeof(pathvar), pathvar, sizeof(pathvar)); > + ptr[3] = tmp - sizeof(pathvar); > + } > + } > + snprintf(cbuf, sizeof(cbuf), "KVM_VM_CREATED=%llu", created); > + snprintf(abuf, sizeof(abuf), "KVM_VM_ACTIVE=%llu", active); > + snprintf(pidbuf, sizeof(pidbuf), "KVM_VM_PID=%s", > + kvm->debugfs_dentry->d_name.name); > + tmp = strchr(pidbuf, '-'); > + if (tmp) > + *tmp = '\0'; > + kobject_uevent_env(&kvm_dev.this_device->kobj, KOBJ_CHANGE, ptr); > + kfree(pathbuf); > +} > + > static int kvm_init_debug(void) > { > int r = -EEXIST; >
Looks good to me (I haven't tested it) for 4.13. Paolo
