From: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
To: Ian Campbell <ian.campbell@citrix.com>
Cc: Andrew Jones <drjones@redhat.com>, <christoffer.dall@linaro.org>,
<marc.zyngier@arm.com>, <stefano.stabellini@eu.citrix.com>,
<tim@xen.org>, <wei@redhat.com>, <kvm@vger.kernel.org>,
<rjones@redhat.com>, <xen-devel@lists.xen.org>,
<kvmarm@lists.cs.columbia.edu>,
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [Xen-devel] ARM: KVM/XEN: how should we support virt-what?
Date: Wed, 25 Mar 2015 17:19:30 +0000 [thread overview]
Message-ID: <alpine.DEB.2.02.1503251718090.7982@kaball.uk.xensource.com> (raw)
In-Reply-To: <1427281736.10784.63.camel@citrix.com>
On Wed, 25 Mar 2015, Ian Campbell wrote:
> On Wed, 2015-03-25 at 10:44 +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. ??.
>
> FWIW Xen has a specific node,
> https://git.kernel.org/cgit/linux/kernel/git/devicetree/devicetree-rebasing.git/tree/Bindings/arm/xen.txt
>
> Doesn't help you with ACPI systems though. IIRC there will be a Xen
> table of some sort.
This is the Xen specific ACPI table:
http://wiki.xenproject.org/mediawiki/images/c/c4/Xen-environment-table.pdf
WARNING: multiple messages have this Message-ID (diff)
From: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
To: Ian Campbell <ian.campbell@citrix.com>
Cc: Andrew Jones <drjones@redhat.com>,
christoffer.dall@linaro.org, marc.zyngier@arm.com,
stefano.stabellini@eu.citrix.com, tim@xen.org, wei@redhat.com,
kvm@vger.kernel.orgrjones@redhat.com, xen-devel@lists.xen.org,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: Re: [Xen-devel] ARM: KVM/XEN: how should we support virt-what?
Date: Wed, 25 Mar 2015 17:19:30 +0000 [thread overview]
Message-ID: <alpine.DEB.2.02.1503251718090.7982@kaball.uk.xensource.com> (raw)
In-Reply-To: <1427281736.10784.63.camel@citrix.com>
On Wed, 25 Mar 2015, Ian Campbell wrote:
> On Wed, 2015-03-25 at 10:44 +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. ??.
>
> FWIW Xen has a specific node,
> https://git.kernel.org/cgit/linux/kernel/git/devicetree/devicetree-rebasing.git/tree/Bindings/arm/xen.txt
>
> Doesn't help you with ACPI systems though. IIRC there will be a Xen
> table of some sort.
This is the Xen specific ACPI table:
http://wiki.xenproject.org/mediawiki/images/c/c4/Xen-environment-table.pdf
WARNING: multiple messages have this Message-ID (diff)
From: stefano.stabellini@eu.citrix.com (Stefano Stabellini)
To: linux-arm-kernel@lists.infradead.org
Subject: [Xen-devel] ARM: KVM/XEN: how should we support virt-what?
Date: Wed, 25 Mar 2015 17:19:30 +0000 [thread overview]
Message-ID: <alpine.DEB.2.02.1503251718090.7982@kaball.uk.xensource.com> (raw)
In-Reply-To: <1427281736.10784.63.camel@citrix.com>
On Wed, 25 Mar 2015, Ian Campbell wrote:
> On Wed, 2015-03-25 at 10:44 +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. ??.
>
> FWIW Xen has a specific node,
> https://git.kernel.org/cgit/linux/kernel/git/devicetree/devicetree-rebasing.git/tree/Bindings/arm/xen.txt
>
> Doesn't help you with ACPI systems though. IIRC there will be a Xen
> table of some sort.
This is the Xen specific ACPI table:
http://wiki.xenproject.org/mediawiki/images/c/c4/Xen-environment-table.pdf
next prev parent reply other threads:[~2015-03-25 17:20 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-25 9:44 ARM: KVM/XEN: how should we support virt-what? Andrew Jones
2015-03-25 9:44 ` Andrew Jones
2015-03-25 10:56 ` Paolo Bonzini
2015-03-25 10:56 ` Paolo Bonzini
2015-03-25 10:56 ` Paolo Bonzini
2015-03-25 11:08 ` [Xen-devel] " Ian Campbell
2015-03-25 11:08 ` Ian Campbell
2015-03-25 11:08 ` Ian Campbell
2015-03-25 17:19 ` Stefano Stabellini
2015-03-25 17:19 ` Stefano Stabellini [this message]
2015-03-25 17:19 ` [Xen-devel] " Stefano Stabellini
2015-03-25 17:19 ` Stefano Stabellini
2015-03-25 11:08 ` Ian Campbell
2015-03-25 12:03 ` Marc Zyngier
2015-03-25 12:03 ` Marc Zyngier
2015-03-25 12:03 ` Marc Zyngier
2015-03-26 9:01 ` Andrew Jones
2015-03-26 9:01 ` Andrew Jones
2015-03-26 9:01 ` Andrew Jones
2015-03-26 18:45 ` Stefano Stabellini
2015-03-26 18:45 ` Stefano Stabellini
2015-03-26 18:45 ` Stefano Stabellini
2015-03-26 18:45 ` Stefano Stabellini
2015-03-26 18:49 ` Ard Biesheuvel
2015-03-26 18:49 ` Ard Biesheuvel
2015-03-26 18:49 ` Ard Biesheuvel
2015-03-26 18:50 ` Ard Biesheuvel
2015-03-26 18:50 ` Ard Biesheuvel
2015-03-26 18:50 ` Ard Biesheuvel
2015-03-27 10:25 ` Andrew Jones
2015-03-27 10:25 ` Andrew Jones
2015-03-27 10:25 ` Andrew Jones
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