From: "Raslan, KarimAllah" <karahmed@amazon.de>
To: "Sironi, Filippo" <sironi@amazon.de>,
"Graf, Alexander" <graf@amazon.com>
Cc: "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
"konrad.wilk@oracle.com" <konrad.wilk@oracle.com>,
"Marc.Zyngier@arm.com" <Marc.Zyngier@arm.com>,
"cohuck@redhat.com" <cohuck@redhat.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"borntraeger@de.ibm.com" <borntraeger@de.ibm.com>,
"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>,
"boris.ostrovsky@oracle.com" <boris.ostrovsky@oracle.com>,
"christoffer.dall@linaro.org" <christoffer.dall@linaro.org>
Subject: Re: [Xen-devel] [PATCH v2 1/2] KVM: Start populating /sys/hypervisor with KVM entries
Date: Fri, 31 May 2019 09:12:03 +0000 [thread overview]
Message-ID: <1559293922.14762.2.camel@amazon.de> (raw)
In-Reply-To: <6b3dadf9-6240-6440-b784-50bec605bf2c@amazon.com>
On Fri, 2019-05-31 at 11:06 +0200, Alexander Graf wrote:
> On 17.05.19 17:41, Sironi, Filippo wrote:
> >
> > >
> > > On 16. May 2019, at 15:50, Graf, Alexander <graf@amazon.com> 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 <sironi@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>". Wouldn't it make sense to follow that pattern for the KVM
> > > one too? Currently, if we can not determine the UUID this will just
> > > return (null).
> > >
> > > Otherwise, looks good to me. Are you aware of any other files we should
> > > provide? Also, is there any reason not to implement ARM as well while at it?
> > >
> > > Alex
> > This originated from a customer request that was using /sys/hypervisor/uuid.
> > My guess is that we would want to expose "type" and "version" moving
> > forward and that's when we hypervisor hooks will be useful on top
> > of arch hooks.
> >
> > On a different note, any idea how to check whether the OS is running
> > virtualized on KVM on ARM and ARM64? kvm_para_available() isn't an
>
>
> Yeah, ARM doesn't have any KVM PV FWIW. I also can't find any explicit
> hint passed into guests that we are indeed running in KVM. The closest
> thing I can see is the SMBIOS product identifier in QEMU which gets
> patched to "KVM Virtual Machine". Maybe we'll have to do with that for
> the sake of backwards compatibility ...
How about "psci_ops.conduit" (PSCI_CONDUIT_HVC vs PSCI_CONDUIT_SMC)?
>
>
> >
> > option and the same is true for S390 where kvm_para_available()
> > always returns true and it would even if a KVM enabled kernel would
> > be running on bare metal.
>
>
> For s390, you can figure the topology out using the sthyi instruction.
> I'm not sure if there is a nice in-kernel API to leverage that though.
> In fact, kvm_para_available() probably should check sthyi output to
> determine whether we really can use it, no? Christian?
>
>
> Alex
>
>
> >
> >
> > I think we will need another arch hook to call a function that says
> > whether the OS is running virtualized on KVM.
> >
> > >
> > > >
> > > > +}
> > > > +
> > > > +static struct kobj_attribute uuid = __ATTR_RO(uuid);
> > > > +
> > > > +static int __init uuid_init(void)
> > > > +{
> > > > + if (!kvm_para_available())
> > > > + return 0;
> > > > + return sysfs_create_file(hypervisor_kobj, &uuid.attr);
> > > > +}
> > > > +
> > > > +device_initcall(uuid_init);
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next prev parent reply other threads:[~2019-05-31 9:12 UTC|newest]
Thread overview: 48+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1539078879-4372-1-git-send-email-sironi@amazon.de>
[not found] ` <c81b65ba-c562-1869-483b-aee5229501e0@de.ibm.com>
2018-10-09 16:21 ` [PATCH] KVM: Start populating /sys/hypervisor with KVM entries Boris Ostrovsky
[not found] ` <61740f41-c7e3-edaf-68ac-2e4c4a99523b@oracle.com>
2018-10-09 17:50 ` Cornelia Huck
2019-05-14 15:16 ` [Xen-devel] " Filippo Sironi
2019-05-14 15:16 ` [Xen-devel] [PATCH v2 1/2] " Filippo Sironi
2019-05-14 15:26 ` Christian Borntraeger
2019-05-14 16:09 ` Sironi, Filippo
2019-05-14 16:09 ` [Xen-devel] " Sironi, Filippo
2019-05-14 16:31 ` Christian Borntraeger
2019-05-14 16:31 ` [Xen-devel] " Christian Borntraeger
2019-05-14 22:08 ` Sironi, Filippo
2019-05-14 22:08 ` [Xen-devel] " Sironi, Filippo
2019-05-14 15:26 ` Christian Borntraeger
2019-05-16 13:50 ` [Xen-devel] " Alexander Graf
2019-05-16 14:02 ` Andrew Cooper
2019-05-16 14:02 ` [Xen-devel] " Andrew Cooper
2019-05-16 14:08 ` Alexander Graf
2019-05-16 14:08 ` [Xen-devel] " Alexander Graf
2019-05-16 15:02 ` Boris Ostrovsky
2019-05-16 15:14 ` Sironi, Filippo
2019-05-16 15:14 ` [Xen-devel] " Sironi, Filippo
2019-05-16 15:02 ` Boris Ostrovsky
2019-05-17 15:41 ` [Xen-devel] " Sironi, Filippo
2019-05-31 9:06 ` Alexander Graf
2019-05-31 9:12 ` Raslan, KarimAllah [this message]
2019-05-31 9:26 ` Alexander Graf
2019-05-31 9:26 ` Alexander Graf
2019-05-31 9:38 ` [Xen-devel] " Marc Zyngier
2019-05-31 9:38 ` Marc Zyngier
2019-05-31 9:12 ` Raslan, KarimAllah
2019-05-31 9:06 ` Alexander Graf
2019-05-17 15:41 ` Sironi, Filippo
2019-05-16 13:50 ` Alexander Graf
2019-05-14 15:16 ` Filippo Sironi
2019-05-14 15:16 ` [Xen-devel] [PATCH v2 2/2] KVM: x86: Implement the arch-specific hook to report the VM UUID Filippo Sironi
2019-05-16 13:56 ` Alexander Graf
2019-05-16 15:25 ` Sironi, Filippo
2019-05-16 15:33 ` Alexander Graf
2019-05-16 16:40 ` Boris Ostrovsky
2019-05-16 17:41 ` Sironi, Filippo
2019-05-16 17:49 ` Alexander Graf
2019-05-16 17:49 ` Alexander Graf
2019-05-16 17:41 ` Sironi, Filippo
2019-05-16 16:40 ` Boris Ostrovsky
2019-05-16 15:33 ` Alexander Graf
2019-05-16 15:25 ` Sironi, Filippo
2019-05-16 13:56 ` Alexander Graf
2019-05-14 15:16 ` Filippo Sironi
2019-05-14 15:16 ` KVM: Start populating /sys/hypervisor with KVM entries Filippo Sironi
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