On Thu, 26 Mar 2015, Andrew Jones wrote: > On Wed, Mar 25, 2015 at 10:44:42AM +0100, Andrew Jones wrote: > > Hello ARM virt maintainers, > > > > I'd like to start a discussion about supporting virt-what[1]. virt-what > > allows userspace to determine if the system it's running on is running > > in a guest, and of what type (KVM, Xen, etc.). Despite it being a best > > effort tool, see the Caveat emptor in [1], it has become quite a useful > > tool, and is showing up in different places, such as OpenStack. If you > > look at the code[2], specifically [3], then you'll see how it works on > > x86, which is to use the dedicated hypervisor cpuid leaves. I'm > > wondering what equivalent we have, or can develop, for arm. > > Here are some thoughts; > > 0) there's already something we can use, and I just need to be told > > about it. > > 1) be as similar as possible to x86 by dedicating some currently > > undefined sysreg bits. This would take buy-in from lots of parties, > > so is not likely the way to go. > > 2) create a specific DT node that will get exposed through sysfs, or > > somewhere. > > 3) same as (2), but just use the nodes currently in mach-virt's DT > > as the indication we're a guest. This would just be a heuristic, > > i.e. "have virtio mmio" && psci.method == hvc, or something, > > and we'd still need a way to know if we're kvm vs. xen vs. ??. > > > > Thanks, > > drew > > > > [1] http://people.redhat.com/~rjones/virt-what/ > > [2] http://git.annexia.org/?p=virt-what.git;a=summary > > [3] http://git.annexia.org/?p=virt-what.git;a=blob_plain;f=virt-what-cpuid-helper.c;hb=HEAD > > Thanks everyone for their responses. So, the current summary seems to > be; > 1) Xen has both a DT node and an ACPI table, virt-what can learn how > to probe those. > 2) We don't have anything yet for KVM, and we're reluctant to create a > specific DT node. Anyway, we'd still need to address ACPI booted > guests some other way. > > For a short-term, DT-only, approach we could go with a heuristic, one > that includes Marc's "if hypervisor node exists, then xen, else kvm" > condition. > > How about SMBIOS for a long-term solution that works for both DT and > ACPI? We're not populating SMBIOS for arm guests yet in qemu, but now > that AAVMF has fw_cfg, we should be able to. On x86 we already have > smbios populated from qemu, although not in a way that allows us to > determine kvm vs. xen vs. tcg. I don't think that SMBIOS works with DT. > Any other suggestions? > > drew > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
