[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] ARM: KVM/XEN: how should we support virt-what?
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. Any other suggestions? drew _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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