From: Andrew Cooper <andrew.cooper3@citrix.com>
To: <xen-devel@lists.xenproject.org>
Subject: Re: [Xen-devel] [PATCH 2/2] x86: explicitly disallow guest access to PPIN
Date: Fri, 1 Nov 2019 18:49:42 +0000 [thread overview]
Message-ID: <d002b40f-1316-a968-4860-186db54bb07f@citrix.com> (raw)
In-Reply-To: <6b27b379-f996-4b33-bf24-178bec5ff6b9@citrix.com>
On 01/11/2019 14:29, Andrew Cooper wrote:
> On 01/11/2019 14:00, Eslam Elnikety wrote:
>> Thanks for this series, Jan.
>>
>> On 30.10.19 11:39, Jan Beulich wrote:
>>> To fulfill the "protected" in its name, don't let the real hardware
>>> values "shine through". Report a control register value expressing this.
>>>
>>> Signed-off-by: Jan Beulich <jbeulich@suse.com>
>>> ---
>>> TBD: Do we want to permit Dom0 access?
>> It would be nice to give an administrator a way to get PPIN outside
>> the context of an MCE when needed.
> I suppose this is a reasonable request. We should expose it to the
> hardware domain.
Actually on further thoughts, I'm going to backtrack slightly.
It is reasonable to give to dom0, but it is not reasonable to provide it
by emulating the MSR interface. The problem is that dom0's result is
sensitive to where it happens to be scheduled.
The only sane way of letting dom0 have access is via a hypercall which
returns "no PPIN" or all sockets information in one go, irrespective of
which socket the current vcpu happens to be executing on.
This leaves us back in the (substantially easier) position of not having
to virtualise the MSR interface to begin with.
~Andrew
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next prev parent reply other threads:[~2019-11-01 18:50 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-30 10:36 [Xen-devel] [PATCH 0/2] x86: Protected Processor Inventory Number (PPIN) support Jan Beulich
2019-10-30 10:39 ` [Xen-devel] [PATCH 1/2] x86: include the PPIN in MCE records when available Jan Beulich
2019-10-30 10:39 ` [Xen-devel] [PATCH 2/2] x86: explicitly disallow guest access to PPIN Jan Beulich
2019-10-30 11:43 ` Andrew Cooper
2019-10-30 12:02 ` Jan Beulich
2019-11-01 18:35 ` Andrew Cooper
2019-11-04 10:04 ` Jan Beulich
2019-11-01 14:00 ` Eslam Elnikety
2019-11-01 14:29 ` Andrew Cooper
2019-11-01 18:49 ` Andrew Cooper [this message]
2019-11-04 12:54 ` Jan Beulich
2019-11-04 8:51 ` Jan Beulich
2019-11-04 8:52 ` Jan Beulich
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