> On 16. May 2019, at 15:50, Graf, Alexander <graf@xxxxxxxxxx> wrote: > > On 14.05.19 08:16, Filippo Sironi wrote: >> Start populating /sys/hypervisor with KVM entries when we're running on >> KVM. This is to replicate functionality that's available when we're >> running on Xen. >> >> Start with /sys/hypervisor/uuid, which users prefer over >> /sys/devices/virtual/dmi/id/product_uuid as a way to recognize a virtual >> machine, since it's also available when running on Xen HVM and on Xen PV >> and, on top of that doesn't require root privileges by default. >> Let's create arch-specific hooks so that different architectures can >> provide different implementations. >> >> Signed-off-by: Filippo Sironi <sironi@xxxxxxxxx> > > I think this needs something akin to > > https://www.kernel.org/doc/Documentation/ABI/stable/sysfs-hypervisor-xen > > to document which files are available. > >> --- >> v2: >> * move the retrieval of the VM UUID out of uuid_show and into >> kvm_para_get_uuid, which is a weak function that can be overwritten >> >> drivers/Kconfig | 2 ++ >> drivers/Makefile | 2 ++ >> drivers/kvm/Kconfig | 14 ++++++++++++++ >> drivers/kvm/Makefile | 1 + >> drivers/kvm/sys-hypervisor.c | 30 ++++++++++++++++++++++++++++++ >> 5 files changed, 49 insertions(+) >> create mode 100644 drivers/kvm/Kconfig >> create mode 100644 drivers/kvm/Makefile >> create mode 100644 drivers/kvm/sys-hypervisor.c >> > > [...] > >> + >> +__weak const char *kvm_para_get_uuid(void) >> +{ >> + return NULL; >> +} >> + >> +static ssize_t uuid_show(struct kobject *obj, >> + struct kobj_attribute *attr, >> + char *buf) >> +{ >> + const char *uuid = kvm_para_get_uuid(); >> + return sprintf(buf, "%s\n", uuid); > > The usual return value for the Xen /sys/hypervisor interface is > "<denied>". Wouldn't it make sense to follow that pattern for the KVM > one too? Currently, if we can not determine the UUID this will just > return (null). > > Otherwise, looks good to me. Are you aware of any other files we should > provide? Also, is there any reason not to implement ARM as well while at it? > > Alex This originated from a customer request that was using /sys/hypervisor/uuid. My guess is that we would want to expose "type" and "version" moving forward and that's when we hypervisor hooks will be useful on top of arch hooks. On a different note, any idea how to check whether the OS is running virtualized on KVM on ARM and ARM64? kvm_para_available() isn't an option and the same is true for S390 where kvm_para_available() always returns true and it would even if a KVM enabled kernel would be running on bare metal. I think we will need another arch hook to call a function that says whether the OS is running virtualized on KVM. >> +} >> + >> +static struct kobj_attribute uuid = __ATTR_RO(uuid); >> + >> +static int __init uuid_init(void) >> +{ >> + if (!kvm_para_available()) >> + return 0; >> + return sysfs_create_file(hypervisor_kobj, &uuid.attr); >> +} >> + >> +device_initcall(uuid_init); Amazon Development Center Germany GmbH Krausenstr. 38 10117 Berlin Geschaeftsfuehrer: Christian Schlaeger, Ralf Herbrich Ust-ID: DE 289 237 879 Eingetragen am Amtsgericht Charlottenburg HRB 149173 B
