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From: "Rafael J. Wysocki" <rafael@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: "Singh, Balbir" <sblbir@amazon.com>,
	"Valentin, Eduardo" <eduval@amazon.com>,
	"boris.ostrovsky@oracle.com" <boris.ostrovsky@oracle.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"Agarwal, Anchal" <anchalag@amazon.com>,
	"Woodhouse, David" <dwmw@amazon.co.uk>,
	"vkuznets@redhat.com" <vkuznets@redhat.com>,
	"sstabellini@kernel.org" <sstabellini@kernel.org>,
	"tglx@linutronix.de" <tglx@linutronix.de>,
	"linux-pm@vger.kernel.org" <linux-pm@vger.kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"pavel@ucw.cz" <pavel@ucw.cz>,
	"axboe@kernel.dk" <axboe@kernel.dk>,
	"x86@kernel.org" <x86@kernel.org>,
	"roger.pau@citrix.com" <roger.pau@citrix.com>,
	"hpa@zytor.com" <hpa@zytor.com>,
	"rjw@rjwysocki.net" <rjw@rjwysocki.net>,
	"mingo@redhat.com" <mingo@redhat.com>,
	"Kamata, Munehisa" <kamatam@amazon.com>,
	"bp@alien8.de" <bp@alien8.de>,
	"netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	"konrad.wilk@oracle.co" <konrad.wilk@oracle.co>,
	"len.brown@intel.com" <len.brown@intel.com>,
	"davem@davemloft.net" <davem@davemloft.net>,
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	"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Subject: Re: [RFC PATCH V2 11/11] x86: tsc: avoid system instability in hibernation
Date: Tue, 14 Jan 2020 00:30:02 +0100
Message-ID: <CAJZ5v0imNbbch=NWAdgVKf_hjwRrEiWAL8SFNwe6rW_SjgYzrw@mail.gmail.com> (raw)
In-Reply-To: <CAJZ5v0jv+5aLY3N4wFSitu61o9S8tJWEWGGn1Xyw-P82_TwFdQ@mail.gmail.com>

On Mon, Jan 13, 2020 at 10:50 PM Rafael J. Wysocki <rafael@kernel.org> wrote:
>
> On Mon, Jan 13, 2020 at 1:43 PM Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > On Mon, Jan 13, 2020 at 11:43:18AM +0000, Singh, Balbir wrote:
> > > For your original comment, just wanted to clarify the following:
> > >
> > > 1. After hibernation, the machine can be resumed on a different but compatible
> > > host (these are VM images hibernated)
> > > 2. This means the clock between host1 and host2 can/will be different
> > >
> > > In your comments are you making the assumption that the host(s) is/are the
> > > same? Just checking the assumptions being made and being on the same page with
> > > them.
> >
> > I would expect this to be the same problem we have as regular suspend,
> > after power off the TSC will have been reset, so resume will have to
> > somehow bridge that gap. I've no idea if/how it does that.
>
> In general, this is done by timekeeping_resume() and the only special
> thing done for the TSC appears to be the tsc_verify_tsc_adjust(true)
> call in tsc_resume().

And I forgot about tsc_restore_sched_clock_state() that gets called
via restore_processor_state() on x86, before calling
timekeeping_resume().

  reply index

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-07 23:45 Anchal Agarwal
2020-01-08 10:50 ` Peter Zijlstra
2020-01-10 15:35   ` Eduardo Valentin
2020-01-13 10:16     ` Peter Zijlstra
2020-01-13 11:43       ` Singh, Balbir
2020-01-13 11:48         ` Rafael J. Wysocki
2020-01-13 12:42         ` Peter Zijlstra
2020-01-13 21:50           ` Rafael J. Wysocki
2020-01-13 23:30             ` Rafael J. Wysocki [this message]
2020-01-14 19:29               ` Anchal Agarwal
2020-01-22 20:07                 ` Anchal Agarwal
2020-01-23 16:27                   ` Boris Ostrovsky
2020-01-13 13:01         ` [Xen-devel] " Andrew Cooper
2020-01-13 13:54           ` David Woodhouse
2020-01-13 15:02           ` Singh, Balbir

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