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From: Roman Kagan <rkagan@virtuozzo.com>
To: "Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	"K. Y. 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
Date: Tue, 20 Dec 2016 18:55:48 +0300	[thread overview]
Message-ID: <20161220155602.6298-2-rkagan@virtuozzo.com> (raw)
In-Reply-To: <20161220155602.6298-1-rkagan@virtuozzo.com>

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.

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 19:12 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 ` Roman Kagan [this message]
2016-12-20 20:57   ` [PATCH 01/15] hyperv: consolidate TSC ref page definitions KY Srinivasan
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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