On 16/05/2019 14:50, Alexander Graf 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 <sir...@amazon.de> > 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>".
This string comes straight from Xen. It was an effort to reduce the quantity of interesting fingerprintable data accessable by default to unprivileged guests. See https://xenbits.xen.org/gitweb/?p=xen.git;a=commitdiff;h=a2fc8d514df2b38c310d4f4432fe06520b0769ed ~Andrew
