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Commit 2deb55aa authored by Michael Kelley's avatar Michael Kelley Committed by Greg Kroah-Hartman
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x86/hyper-v: Enable PIT shutdown quirk 



commit 1de72c706488b7be664a601cf3843bd01e327e58 upstream.

Hyper-V emulation of the PIT has a quirk such that the normal PIT shutdown
path doesn't work, because clearing the counter register restarts the
timer.

Disable the counter clearing on PIT shutdown.

Signed-off-by: default avatarMichael Kelley <mikelley@microsoft.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Cc: "gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>
Cc: "devel@linuxdriverproject.org" <devel@linuxdriverproject.org>
Cc: "daniel.lezcano@linaro.org" <daniel.lezcano@linaro.org>
Cc: "virtualization@lists.linux-foundation.org" <virtualization@lists.linux-foundation.org>
Cc: "jgross@suse.com" <jgross@suse.com>
Cc: "akataria@vmware.com" <akataria@vmware.com>
Cc: "olaf@aepfle.de" <olaf@aepfle.de>
Cc: "apw@canonical.com" <apw@canonical.com>
Cc: vkuznets <vkuznets@redhat.com>
Cc: "jasowang@redhat.com" <jasowang@redhat.com>
Cc: "marcelo.cerri@canonical.com" <marcelo.cerri@canonical.com>
Cc: KY Srinivasan <kys@microsoft.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/1541303219-11142-3-git-send-email-mikelley@microsoft.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent e73cb6a6

arch/x86/kernel/cpu/mshyperv.c

+11 −0
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 
#include <linux/interrupt.h>

#include <linux/irq.h>

#include <linux/kexec.h>

#include <linux/i8253.h>

#include <asm/processor.h>

#include <asm/hypervisor.h>

#include <asm/hyperv-tlfs.h>
@@ -285,6 +286,16 @@ static void __init ms_hyperv_init_platform(void) 
	if (efi_enabled(EFI_BOOT))

		x86_platform.get_nmi_reason = hv_get_nmi_reason;



	/*

	 * Hyper-V VMs have a PIT emulation quirk such that zeroing the

	 * counter register during PIT shutdown restarts the PIT. So it

	 * continues to interrupt @18.2 HZ. Setting i8253_clear_counter

	 * to false tells pit_shutdown() not to zero the counter so that

	 * the PIT really is shutdown. Generation 2 VMs don't have a PIT,

	 * and setting this value has no effect.

	 */

	i8253_clear_counter_on_shutdown = false;



#if IS_ENABLED(CONFIG_HYPERV)

	/*

	 * Setup the hook to get control post apic initialization.