From: Alexander Graf <graf@amazon.com>
To: Andrew Cooper <andrew.cooper3@citrix.com>,
Filippo Sironi <sironi@amazon.de>, <linux-kernel@vger.kernel.org>,
<kvm@vger.kernel.org>, <borntraeger@de.ibm.com>,
<boris.ostrovsky@oracle.com>, <cohuck@redhat.com>,
<konrad.wilk@oracle.com>, <xen-devel@lists.xenproject.org>
Subject: Re: [Xen-devel] [PATCH v2 1/2] KVM: Start populating /sys/hypervisor with KVM entries
Date: Thu, 16 May 2019 07:08:13 -0700 [thread overview]
Message-ID: <22fadfb1-e48d-ccb6-0e42-c105b7335d7a@amazon.com> (raw)
In-Reply-To: <7aae3e49-5b1c-96d1-466e-5b061305dc9d@citrix.com>
On 16.05.19 07:02, Andrew Cooper wrote:
> On 16/05/2019 14:50, Alexander Graf 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>".
> This string comes straight from Xen.
>
> It was an effort to reduce the quantity of interesting fingerprintable
> data accessable by default to unprivileged guests.
>
> See
> https://xenbits.xen.org/gitweb/?p=xen.git;a=commitdiff;h=a2fc8d514df2b38c310d4f4432fe06520b0769ed
What a great design :). My point is mostly that we should be as common
as possible when it comes to /sys/hypervisor, so that tools don't have
to care about the HV they're working against.
By being first to implement <denied> you just created precedence, so we
can either simulate the same behavor for KVM or be different. And since
commonality is good, I'd rather be the same.
That said, I couldn't find in the patdch above whether Xen even emits
<denied> for the uuid. Does it have that capability? If not, we may as
well go with (null).
Alex
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next prev parent reply other threads:[~2019-05-16 14:08 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 ` Alexander Graf [this message]
2019-05-16 15:02 ` [Xen-devel] " 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
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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