From: Paolo Bonzini <pbonzini@redhat.com>
To: Andy Lutomirski <luto@amacapital.net>,
Marcelo Tosatti <mtosatti@redhat.com>
Cc: Gleb Natapov <gleb@kernel.org>, kvm list <kvm@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: Cleaning up the KVM clock
Date: Mon, 22 Dec 2014 23:49:20 +0100 [thread overview]
Message-ID: <54989FF0.3090300@redhat.com> (raw)
In-Reply-To: <CALCETrXU+Z_t3qon+DR1hUiqSgpWLe9w74guBxbDG68ytM0icg@mail.gmail.com>
On 22/12/2014 17:03, Andy Lutomirski wrote:
> This is wrong. The guest *kernel* might not see the intermediate
> state because the kernel (presumably it disabled migration while
> reading pvti), but the guest vdso can't do that and could very easily
> observe pvti while it's being written.
No. kvm_guest_time_update is called by vcpu_enter_guest, while the vCPU
is not running, so it's entirely atomic from the point of view of the guest.
> I'll send patches for the whole mess, complete with lots of comments,
> after I test them a bit today.
Ok, some comments can certainly help the discussion.
Paolo
next prev parent reply other threads:[~2014-12-22 22:49 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-21 3:31 Cleaning up the KVM clock Andy Lutomirski
2014-12-22 10:15 ` Paolo Bonzini
2014-12-22 13:34 ` Marcelo Tosatti
2014-12-22 14:09 ` Marcelo Tosatti
2014-12-22 16:03 ` Andy Lutomirski
2014-12-22 22:47 ` Paolo Bonzini
2014-12-22 22:49 ` Paolo Bonzini [this message]
2014-12-22 23:00 ` Andy Lutomirski
2014-12-22 23:14 ` Paolo Bonzini
2014-12-22 23:31 ` Andy Lutomirski
[not found] ` <CAAyOgsbNsDmPGzJcEuYExaswWaQoLHzkMVd+r6r-8jnGc00yTA@mail.gmail.com>
2014-12-23 10:25 ` Paolo Bonzini
2014-12-22 13:38 ` Marcelo Tosatti
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