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From: KY Srinivasan <kys@microsoft.com>
To: "Roman Kagan" <rkagan@virtuozzo.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	"Vitaly Kuznetsov" <vkuznets@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	"x86@kernel.org" <x86@kernel.org>,
	"Haiyang Zhang" <haiyangz@microsoft.com>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"devel@linuxdriverproject.org" <devel@linuxdriverproject.org>,
	"Denis V . Lunev" <den@openvz.org>
Subject: RE: [PATCH 01/15] hyperv: consolidate TSC ref page definitions
Date: Tue, 20 Dec 2016 20:57:28 +0000	[thread overview]
Message-ID: <DM5PR03MB2490A3E5A6DEB22249884DECA0900@DM5PR03MB2490.namprd03.prod.outlook.com> (raw)
In-Reply-To: <20161220155602.6298-2-rkagan@virtuozzo.com>



> -----Original Message-----
> From: Roman Kagan [mailto:rkagan@virtuozzo.com]
> Sent: Tuesday, December 20, 2016 7:56 AM
> To: Paolo Bonzini <pbonzini@redhat.com>; Radim Krčmář
> <rkrcmar@redhat.com>; KY Srinivasan <kys@microsoft.com>; Vitaly
> Kuznetsov <vkuznets@redhat.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>; Ingo Molnar
> <mingo@redhat.com>; H. Peter Anvin <hpa@zytor.com>; x86@kernel.org;
> Haiyang Zhang <haiyangz@microsoft.com>; kvm@vger.kernel.org; linux-
> kernel@vger.kernel.org; devel@linuxdriverproject.org; Denis V . Lunev
> <den@openvz.org>; Roman Kagan <rkagan@virtuozzo.com>
> Subject: [PATCH 01/15] hyperv: consolidate TSC ref page definitions
> 
> Consolidate the guest-side and kvm-side definitions for Hyper-V TSC
> reference page.
> 
> While at this, rewrite read_hv_clock_tsc using the existing helpers.

Why not beak this into separate patches.
> 
> Signed-off-by: Roman Kagan <rkagan@virtuozzo.com>
> ---
>  arch/x86/include/asm/kvm_host.h    |  2 +-
>  arch/x86/include/uapi/asm/hyperv.h |  4 +--
>  drivers/hv/hyperv_vmbus.h          |  8 ------
>  arch/x86/kvm/hyperv.c              |  4 +--
>  drivers/hv/hv.c                    | 54 +++++++++++++++-----------------------
>  5 files changed, 26 insertions(+), 46 deletions(-)
> 
> diff --git a/arch/x86/include/asm/kvm_host.h
> b/arch/x86/include/asm/kvm_host.h
> index 2e25038..2b85f49 100644
> --- a/arch/x86/include/asm/kvm_host.h
> +++ b/arch/x86/include/asm/kvm_host.h
> @@ -713,7 +713,7 @@ struct kvm_hv {
>  	u64 hv_crash_param[HV_X64_MSR_CRASH_PARAMS];
>  	u64 hv_crash_ctl;
> 
> -	HV_REFERENCE_TSC_PAGE tsc_ref;
> +	struct hv_ref_tsc_page tsc_ref;
>  };
> 
>  struct kvm_arch {
> diff --git a/arch/x86/include/uapi/asm/hyperv.h
> b/arch/x86/include/uapi/asm/hyperv.h
> index 9b1a918..6098ab5 100644
> --- a/arch/x86/include/uapi/asm/hyperv.h
> +++ b/arch/x86/include/uapi/asm/hyperv.h
> @@ -252,12 +252,12 @@
>  #define HV_STATUS_INVALID_CONNECTION_ID		18
>  #define HV_STATUS_INSUFFICIENT_BUFFERS		19
> 
> -typedef struct _HV_REFERENCE_TSC_PAGE {
> +struct hv_ref_tsc_page {
>  	__u32 tsc_sequence;
>  	__u32 res1;
>  	__u64 tsc_scale;
>  	__s64 tsc_offset;
> -} HV_REFERENCE_TSC_PAGE, *PHV_REFERENCE_TSC_PAGE;
> +};
> 
>  /* Define the number of synthetic interrupt sources. */
>  #define HV_SYNIC_SINT_COUNT		(16)
> diff --git a/drivers/hv/hyperv_vmbus.h b/drivers/hv/hyperv_vmbus.h
> index 0675b39..4516498 100644
> --- a/drivers/hv/hyperv_vmbus.h
> +++ b/drivers/hv/hyperv_vmbus.h
> @@ -475,14 +475,6 @@ struct hv_context {
> 
>  extern struct hv_context hv_context;
> 
> -struct ms_hyperv_tsc_page {
> -	volatile u32 tsc_sequence;
> -	u32 reserved1;
> -	volatile u64 tsc_scale;
> -	volatile s64 tsc_offset;
> -	u64 reserved2[509];
> -};
> -
>  struct hv_ring_buffer_debug_info {
>  	u32 current_interrupt_mask;
>  	u32 current_read_index;
> diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
> index 1572c35..c7db112 100644
> --- a/arch/x86/kvm/hyperv.c
> +++ b/arch/x86/kvm/hyperv.c
> @@ -806,7 +806,7 @@ static int kvm_hv_msr_set_crash_data(struct
> kvm_vcpu *vcpu,
>   * These two equivalencies are implemented in this function.
>   */
>  static bool compute_tsc_page_parameters(struct pvclock_vcpu_time_info
> *hv_clock,
> -					HV_REFERENCE_TSC_PAGE *tsc_ref)
> +					struct hv_ref_tsc_page *tsc_ref)
>  {
>  	u64 max_mul;
> 
> @@ -847,7 +847,7 @@ void kvm_hv_setup_tsc_page(struct kvm *kvm,
>  	u64 gfn;
> 
>  	BUILD_BUG_ON(sizeof(tsc_seq) != sizeof(hv-
> >tsc_ref.tsc_sequence));
> -	BUILD_BUG_ON(offsetof(HV_REFERENCE_TSC_PAGE,
> tsc_sequence) != 0);
> +	BUILD_BUG_ON(offsetof(struct hv_ref_tsc_page, tsc_sequence) !=
> 0);
> 
>  	if (!(hv->hv_tsc_page & HV_X64_MSR_TSC_REFERENCE_ENABLE))
>  		return;
> diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
> index 446802a..a7256ec 100644
> --- a/drivers/hv/hv.c
> +++ b/drivers/hv/hv.c
> @@ -137,41 +137,29 @@ EXPORT_SYMBOL_GPL(hv_do_hypercall);
>  #ifdef CONFIG_X86_64
>  static cycle_t read_hv_clock_tsc(struct clocksource *arg)
>  {
> -	cycle_t current_tick;
> -	struct ms_hyperv_tsc_page *tsc_pg = hv_context.tsc_page;
> +	struct hv_ref_tsc_page *tsc_pg = hv_context.tsc_page;
> +	u32 sequence;
> +	u64 scale;
> +	s64 offset;
> +
> +	do {
> +		sequence = tsc_pg->tsc_sequence;
> +		virt_rmb();
> +
> +		if (!sequence) {
> +			/* fallback to MSR */
> +			cycle_t current_tick;
> +			rdmsrl(HV_X64_MSR_TIME_REF_COUNT,
> current_tick);
> +			return current_tick;
> +		}
> 
> -	if (tsc_pg->tsc_sequence != 0) {
> -		/*
> -		 * Use the tsc page to compute the value.
> -		 */
> +		scale = tsc_pg->tsc_scale;
> +		offset = tsc_pg->tsc_offset;
> 
> -		while (1) {
> -			cycle_t tmp;
> -			u32 sequence = tsc_pg->tsc_sequence;
> -			u64 cur_tsc;
> -			u64 scale = tsc_pg->tsc_scale;
> -			s64 offset = tsc_pg->tsc_offset;
> -
> -			rdtscll(cur_tsc);
> -			/* current_tick = ((cur_tsc *scale) >> 64) + offset */
> -			asm("mulq %3"
> -				: "=d" (current_tick), "=a" (tmp)
> -				: "a" (cur_tsc), "r" (scale));
> -
> -			current_tick += offset;
> -			if (tsc_pg->tsc_sequence == sequence)
> -				return current_tick;
> -
> -			if (tsc_pg->tsc_sequence != 0)
> -				continue;
> -			/*
> -			 * Fallback using MSR method.
> -			 */
> -			break;
> -		}
> -	}
> -	rdmsrl(HV_X64_MSR_TIME_REF_COUNT, current_tick);
> -	return current_tick;
> +		virt_rmb();
> +	} while (tsc_pg->tsc_sequence != sequence);
> +
> +	return mul_u64_u64_shr(rdtsc_ordered(), scale, 64) + offset;
>  }
> 
>  static struct clocksource hyperv_cs_tsc = {
> --
> 2.9.3

  reply	other threads:[~2016-12-20 20:57 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-20 15:55 [PATCH 00/15] hyperv: more stuff to uapi + cleanup Roman Kagan
2016-12-20 15:55 ` [PATCH 01/15] hyperv: consolidate TSC ref page definitions Roman Kagan
2016-12-20 20:57   ` KY Srinivasan [this message]
2016-12-21  6:25     ` Roman Kagan
2016-12-20 15:55 ` [PATCH 02/15] hyperv: uapi-fy synic event flags definitions Roman Kagan
2016-12-20 17:24   ` Stephen Hemminger
2016-12-21  6:33     ` Roman Kagan
2016-12-21 10:58   ` kbuild test robot
2016-12-21 18:58   ` KY Srinivasan
2016-12-20 15:55 ` [PATCH 03/15] hyperv: use standard bitops Roman Kagan
2016-12-21 12:00   ` Olaf Hering
2016-12-21 13:23     ` Roman Kagan
2016-12-22 12:33       ` Paolo Bonzini
2016-12-21 19:08   ` KY Srinivasan
2016-12-20 15:55 ` [PATCH 04/15] hyperv: define VMBus message type Roman Kagan
2016-12-20 15:55 ` [PATCH 05/15] hyperv: GFP_ATOMIC -> GFP_KERNEL Roman Kagan
2016-12-20 15:55 ` [PATCH 06/15] hyperv: avoid unnecessary vmalloc Roman Kagan
2016-12-21 19:19   ` KY Srinivasan
2016-12-20 15:55 ` [PATCH 07/15] hyperv: dedup cpuid definitions Roman Kagan
2016-12-20 15:55 ` [PATCH 08/15] hyperv: dedup crash msr related definitions Roman Kagan
2016-12-20 15:55 ` [PATCH 09/15] hyperv: unify Hyper-V msr definitions Roman Kagan
2016-12-20 15:55 ` [PATCH 10/15] hyperv: uapi-fy PostMessage and SignalEvent hypercall structures Roman Kagan
2016-12-21 19:27   ` KY Srinivasan
2016-12-20 15:55 ` [PATCH 11/15] hyperv: uapi-fy monitored notification structures Roman Kagan
2016-12-20 15:55 ` [PATCH 12/15] hyperv: move VMBus connection ids to uapi Roman Kagan
2016-12-20 17:25   ` Stephen Hemminger
2016-12-21  6:29     ` Roman Kagan
2016-12-21 12:18       ` Christoph Hellwig
2016-12-21 12:59         ` Roman Kagan
2016-12-21 14:26           ` Christoph Hellwig
2016-12-21 14:39             ` Roman Kagan
2016-12-21 15:39             ` Paolo Bonzini
2016-12-21 15:43               ` Christoph Hellwig
2016-12-21 17:25                 ` Paolo Bonzini
2016-12-21 17:50                 ` Stephen Hemminger
2016-12-21 17:53                   ` Paolo Bonzini
2016-12-21 17:58                   ` Christoph Hellwig
2016-12-21 18:02                     ` Stephen Hemminger
2016-12-21 19:54                       ` KY Srinivasan
2016-12-28 17:09                         ` Roman Kagan
2016-12-29 18:29                           ` Stephen Hemminger
2017-01-02  8:19                           ` Paolo Bonzini
2017-01-09  8:32                             ` Roman Kagan
2017-01-09  8:40                               ` hpa
2017-01-09  8:58                                 ` Roman Kagan
2017-01-09  9:02                                 ` Paolo Bonzini
2017-01-02 19:39                           ` Stephen Hemminger
2017-01-03  9:32                             ` Paolo Bonzini
2016-12-20 15:56 ` [PATCH 13/15] hyperv: move function close to its only callsite Roman Kagan
2016-12-20 15:56 ` [PATCH 14/15] hyperv_vmbus: drop unused definitions Roman Kagan
2016-12-20 15:56 ` [PATCH 15/15] hyperv: redefine hv_message without bitfields Roman Kagan
2016-12-21 18:00 ` [PATCH 00/15] hyperv: more stuff to uapi + cleanup KY Srinivasan
2016-12-28 16:57   ` Roman Kagan
2016-12-30 19:45     ` KY Srinivasan

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