RE: [PATCH 1/1] Staging: hv: Integrate the time source driver withHyper-V detection code

[KY Srinivasan]

> -----Original Message-----
> From: K. Y. Srinivasan [mailto:kys@xxxxxxxxxxxxx]
> Sent: Friday, July 15, 2011 9:01 PM
> To: gregkh@xxxxxxx; linux-kernel@xxxxxxxxxxxxxxx;
> devel@xxxxxxxxxxxxxxxxxxxxxx; virtualization@xxxxxxxxxxxxxx; tglx@xxxxxxxxxxxxx
> Cc: KY Srinivasan; Haiyang Zhang
> Subject: [PATCH 1/1] Staging: hv: Integrate the time source driver with Hyper-V
> detection code
> 
> The Hyper-V timesource driver is best integrated with Hyper-V detection code
> since: (a) Linux guests running on Hyper-V need this timesource and (b)
> by integrating with Hyper-V detection, we could significantly  minimize the
> code in the timesource driver.

Thomas,

A number of weeks ago you had reviewed the time Hyper-V time source driver code
and recommended that I merge it with Hyper-V detection code. That is exactly what I 
have done here. Is this what you had in mind; your feedback would be greatly appreciated.
I had sent this patch a couple of weeks ago and got no response. As an X86 maintainer,
would you be willing to take this patch.


Regards,

K. Y

> 
> Signed-off-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx>
> Signed-off-by: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
> ---
>  arch/x86/kernel/cpu/mshyperv.c     |   24 ++++++++
>  drivers/staging/hv/Makefile        |    2 +-
>  drivers/staging/hv/hv_timesource.c |  102 ------------------------------------
>  3 files changed, 25 insertions(+), 103 deletions(-)
>  delete mode 100644 drivers/staging/hv/hv_timesource.c
> 
> diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
> index d944bf6..c97f88d 100644
> --- a/arch/x86/kernel/cpu/mshyperv.c
> +++ b/arch/x86/kernel/cpu/mshyperv.c
> @@ -11,6 +11,8 @@
>   */
> 
>  #include <linux/types.h>
> +#include <linux/time.h>
> +#include <linux/clocksource.h>
>  #include <linux/module.h>
>  #include <asm/processor.h>
>  #include <asm/hypervisor.h>
> @@ -36,6 +38,25 @@ static bool __init ms_hyperv_platform(void)
>  		!memcmp("Microsoft Hv", hyp_signature, 12);
>  }
> 
> +static cycle_t read_hv_clock(struct clocksource *arg)
> +{
> +	cycle_t current_tick;
> +	/*
> +	 * Read the partition counter to get the current tick count. This count
> +	 * is set to 0 when the partition is created and is incremented in
> +	 * 100 nanosecond units.
> +	 */
> +	rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
> +	return current_tick;
> +}
> +
> +static struct clocksource hyperv_cs = {
> +	.name           = "hyperv_clocksource",
> +	.rating         = 400, /* use this when running on Hyperv*/
> +	.read           = read_hv_clock,
> +	.mask           = CLOCKSOURCE_MASK(64),
> +};
> +
>  static void __init ms_hyperv_init_platform(void)
>  {
>  	/*
> @@ -46,6 +67,9 @@ static void __init ms_hyperv_init_platform(void)
> 
>  	printk(KERN_INFO "HyperV: features 0x%x, hints 0x%x\n",
>  	       ms_hyperv.features, ms_hyperv.hints);
> +
> +
> +	clocksource_register_hz(&hyperv_cs, NSEC_PER_SEC/100);
>  }
> 
>  const __refconst struct hypervisor_x86 x86_hyper_ms_hyperv = {
> diff --git a/drivers/staging/hv/Makefile b/drivers/staging/hv/Makefile
> index bd176b1..3e0d7e6 100644
> --- a/drivers/staging/hv/Makefile
> +++ b/drivers/staging/hv/Makefile
> @@ -1,4 +1,4 @@
> -obj-$(CONFIG_HYPERV)		+= hv_vmbus.o hv_timesource.o
> +obj-$(CONFIG_HYPERV)		+= hv_vmbus.o
>  obj-$(CONFIG_HYPERV_STORAGE)	+= hv_storvsc.o
>  obj-$(CONFIG_HYPERV_NET)	+= hv_netvsc.o
>  obj-$(CONFIG_HYPERV_UTILS)	+= hv_utils.o
> diff --git a/drivers/staging/hv/hv_timesource.c
> b/drivers/staging/hv/hv_timesource.c
> deleted file mode 100644
> index 0efb049..0000000
> --- a/drivers/staging/hv/hv_timesource.c
> +++ /dev/null
> @@ -1,102 +0,0 @@
> -/*
> - * A clocksource for Linux running on HyperV.
> - *
> - *
> - * Copyright (C) 2010, Novell, Inc.
> - * Author : K. Y. Srinivasan <ksrinivasan@xxxxxxxxxx>
> - *
> - * This program is free software; you can redistribute it and/or modify
> - * it under the terms of the GNU General Public License version 2 as
> - * published by the Free Software Foundation.
> - *
> - * This program is distributed in the hope that it will be useful, but
> - * WITHOUT ANY WARRANTY; without even the implied warranty of
> - * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
> - * NON INFRINGEMENT.  See the GNU General Public License for more
> - * details.
> - *
> - * You should have received a copy of the GNU General Public License
> - * along with this program; if not, write to the Free Software
> - * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
> - *
> - */
> -#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> -
> -#include <linux/version.h>
> -#include <linux/clocksource.h>
> -#include <linux/init.h>
> -#include <linux/module.h>
> -#include <linux/pci.h>
> -#include <linux/dmi.h>
> -#include <asm/hyperv.h>
> -#include <asm/mshyperv.h>
> -#include <asm/hypervisor.h>
> -
> -#define HV_CLOCK_SHIFT	22
> -
> -static cycle_t read_hv_clock(struct clocksource *arg)
> -{
> -	cycle_t current_tick;
> -	/*
> -	 * Read the partition counter to get the current tick count. This count
> -	 * is set to 0 when the partition is created and is incremented in
> -	 * 100 nanosecond units.
> -	 */
> -	rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
> -	return current_tick;
> -}
> -
> -static struct clocksource hyperv_cs = {
> -	.name           = "hyperv_clocksource",
> -	.rating         = 400, /* use this when running on Hyperv*/
> -	.read           = read_hv_clock,
> -	.mask           = CLOCKSOURCE_MASK(64),
> -	/*
> -	 * The time ref counter in HyperV is in 100ns units.
> -	 * The definition of mult is:
> -	 * mult/2^shift = ns/cyc = 100
> -	 * mult = (100 << shift)
> -	 */
> -	.mult           = (100 << HV_CLOCK_SHIFT),
> -	.shift          = HV_CLOCK_SHIFT,
> -};
> -
> -static const struct dmi_system_id __initconst
> -hv_timesource_dmi_table[] __maybe_unused  = {
> -	{
> -		.ident = "Hyper-V",
> -		.matches = {
> -			DMI_MATCH(DMI_SYS_VENDOR, "Microsoft
> Corporation"),
> -			DMI_MATCH(DMI_PRODUCT_NAME, "Virtual Machine"),
> -			DMI_MATCH(DMI_BOARD_NAME, "Virtual Machine"),
> -		},
> -	},
> -	{ },
> -};
> -MODULE_DEVICE_TABLE(dmi, hv_timesource_dmi_table);
> -
> -static const struct pci_device_id __initconst
> -hv_timesource_pci_table[] __maybe_unused = {
> -	{ PCI_DEVICE(0x1414, 0x5353) }, /* VGA compatible controller */
> -	{ 0 }
> -};
> -MODULE_DEVICE_TABLE(pci, hv_timesource_pci_table);
> -
> -
> -static int __init init_hv_clocksource(void)
> -{
> -	if ((x86_hyper != &x86_hyper_ms_hyperv) ||
> -		!(ms_hyperv.features &
> HV_X64_MSR_TIME_REF_COUNT_AVAILABLE))
> -		return -ENODEV;
> -
> -	if (!dmi_check_system(hv_timesource_dmi_table))
> -		return -ENODEV;
> -
> -	pr_info("Registering HyperV clock source\n");
> -	return clocksource_register(&hyperv_cs);
> -}
> -
> -module_init(init_hv_clocksource);
> -MODULE_DESCRIPTION("HyperV based clocksource");
> -MODULE_AUTHOR("K. Y. Srinivasan <ksrinivasan@xxxxxxxxxx>");
> -MODULE_LICENSE("GPL");
> --
> 1.7.4.1
> 

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