linux-kernel - [PATCH 0/2] i8253: Fix PIT shutdown quirk on Hyper-V

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Message-ID: <1541093374-10496-1-git-send-email-mikelley@microsoft.com>
Date:   Thu, 1 Nov 2018 17:30:46 +0000
From:   Michael Kelley <mikelley@...rosoft.com>
To:     "virtualization@...ts.linux-foundation.org" 
        <virtualization@...ts.linux-foundation.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "daniel.lezcano@...aro.org" <daniel.lezcano@...aro.org>,
        "jgross@...e.com" <jgross@...e.com>,
        "akataria@...are.com" <akataria@...are.com>,
        "olaf@...fle.de" <olaf@...fle.de>,
        "apw@...onical.com" <apw@...onical.com>,
        vkuznets <vkuznets@...hat.com>,
        "jasowang@...hat.com" <jasowang@...hat.com>,
        "marcelo.cerri@...onical.com" <marcelo.cerri@...onical.com>,
        KY Srinivasan <kys@...rosoft.com>
CC:     Michael Kelley <mikelley@...rosoft.com>
Subject: [PATCH 0/2] i8253: Fix PIT shutdown quirk on Hyper-V

pit_shutdown() doesn't work on Hyper-V because of a quirk in the
PIT emulation. This problem exists in all versions of Hyper-V and
had not been noticed previously. When the counter register is set
to zero, the emulated PIT continues to interrupt @18.2 HZ.

So add a test for running on Hyper-V, and use that test to skip
setting the counter register when running on Hyper-V.

This patch replaces a previously proposed patch with a different
approach. This new approach follows comments from Thomas Gleixner.

Michael Kelley (2):
  include/linux/hypervisor.h: Add test for running on Hyper-V
  i8253: Fix PIT shutdown quirk on Hyper-V

 drivers/clocksource/i8253.c | 14 ++++++++++++--
 include/linux/hypervisor.h  | 11 +++++++++++
 2 files changed, 23 insertions(+), 2 deletions(-)

-- 
1.8.3.1