This small series picks up work from Amazon that seems to have stalled out later year around this time: listening for the vmgenid ACPI notification, and using it to "do something." Last year, that something involved a complicated userspace mmap chardev, which seems frought with difficulty. This year, I have something much simpler in mind: simply using those ACPI notifications to tell the RNG to reinitialize safely, so we don't repeat random numbers in cloned, forked, or rolled-back VM instances. This series consists of two patches. The first is a rather straightforward addition to random.c, which I feel fine about. The second patch is the reason this is just an RFC: it's a cleanup of the ACPI driver from last year, and I don't really have much experience writing, testing, debugging, or maintaining these types of drivers. Ideally this thread would yield somebody saying, "I see the intent of this; I'm happy to take over ownership of this part." That way, I can focus on the RNG part, and whoever steps up for the paravirt ACPI part can focus on that. As a final note, this series intentionally does _not_ focus on notification of these events to userspace or to other kernel consumers. Since these VM fork detection events first need to hit the RNG, we can later talk about what sorts of notifications or mmap'd counters the RNG should be making accessible to elsewhere. But that's a different sort of project and ties into a lot of more complicated concerns beyond this more basic patchset. So hopefully we can keep the discussion rather focused here to this ACPI business. Cc: dwmw@xxxxxxxxxxxx Cc: acatan@xxxxxxxxxx Cc: graf@xxxxxxxxxx Cc: colmmacc@xxxxxxxxxx Cc: sblbir@xxxxxxxxxx Cc: raduweis@xxxxxxxxxx Cc: jannh@xxxxxxxxxx Cc: gregkh@xxxxxxxxxxxxxxxxxxx Cc: tytso@xxxxxxx Jason A. Donenfeld (2): random: add mechanism for VM forks to reinitialize crng drivers/virt: add vmgenid driver for reinitializing RNG drivers/char/random.c | 58 ++++++++++++++++++ drivers/virt/Kconfig | 8 +++ drivers/virt/Makefile | 1 + drivers/virt/vmgenid.c | 133 +++++++++++++++++++++++++++++++++++++++++ include/linux/random.h | 1 + 5 files changed, 201 insertions(+) create mode 100644 drivers/virt/vmgenid.c -- 2.35.1
