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From 62ac85ec7c8e41b0454bdec0e0a9c7d5adc39280 Mon Sep 17 00:00:00 2001
From: "Dr. David Alan Gilbert (git)" <dgilbert@redhat.com>
Date: Wed, 22 Oct 2014 09:46:34 +0200
Subject: [PATCH 3/6] Revert "kvmclock: Ensure time in migration never goes
 backward"

Message-id: <1413971197-4624-3-git-send-email-dgilbert@redhat.com>
Patchwork-id: 61788
O-Subject: [RHEL-7.1 qemu-kvm PATCH 2/5] Revert "kvmclock: Ensure time in migration never goes backward"
Bugzilla: 1098602 1130428
RH-Acked-by: Marcelo Tosatti <mtosatti@redhat.com>
RH-Acked-by: Eduardo Habkost <ehabkost@redhat.com>
RH-Acked-by: Paolo Bonzini <pbonzini@redhat.com>

From: "Dr. David Alan Gilbert" <dgilbert@redhat.com>

This reverts commit 4b6035c2a739bc4c086abbb36f0883a1178a8f1c.

The equivalent upstream revert is Paolo's fa666c10f2f3e15685ff

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Signed-off-by: Miroslav Rezanina <mrezanin@redhat.com>
---
 hw/i386/kvm/clock.c | 49 -------------------------------------------------
 1 file changed, 49 deletions(-)

diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c
index 1f2a26e..6d6f3a7 100644
--- a/hw/i386/kvm/clock.c
+++ b/hw/i386/kvm/clock.c
@@ -14,7 +14,6 @@
  */
 
 #include "qemu-common.h"
-#include "qemu/host-utils.h"
 #include "sysemu/sysemu.h"
 #include "sysemu/kvm.h"
 #include "hw/sysbus.h"
@@ -29,48 +28,6 @@ typedef struct KVMClockState {
     bool clock_valid;
 } KVMClockState;
 
-struct pvclock_vcpu_time_info {
-    uint32_t   version;
-    uint32_t   pad0;
-    uint64_t   tsc_timestamp;
-    uint64_t   system_time;
-    uint32_t   tsc_to_system_mul;
-    int8_t     tsc_shift;
-    uint8_t    flags;
-    uint8_t    pad[2];
-} __attribute__((__packed__)); /* 32 bytes */
-
-static uint64_t kvmclock_current_nsec(KVMClockState *s)
-{
-    CPUArchState *acpu = first_cpu;
-    CPUState *cpu = ENV_GET_CPU(acpu);
-    CPUX86State *env = cpu->env_ptr;
-    hwaddr kvmclock_struct_pa = env->system_time_msr & ~1ULL;
-    uint64_t migration_tsc = env->tsc;
-    struct pvclock_vcpu_time_info time;
-    uint64_t delta;
-    uint64_t nsec_lo;
-    uint64_t nsec_hi;
-    uint64_t nsec;
-
-    if (!(env->system_time_msr & 1ULL)) {
-        /* KVM clock not active */
-        return 0;
-    }
-
-    cpu_physical_memory_read(kvmclock_struct_pa, &time, sizeof(time));
-
-    delta = migration_tsc - time.tsc_timestamp;
-    if (time.tsc_shift < 0) {
-        delta >>= -time.tsc_shift;
-    } else {
-        delta <<= time.tsc_shift;
-    }
-
-    mulu64(&nsec_lo, &nsec_hi, delta, time.tsc_to_system_mul);
-    nsec = (nsec_lo >> 32) | (nsec_hi << 32);
-    return nsec + time.system_time;
-}
 
 static void kvmclock_vm_state_change(void *opaque, int running,
                                      RunState state)
@@ -82,15 +39,9 @@ static void kvmclock_vm_state_change(void *opaque, int running,
 
     if (running) {
         struct kvm_clock_data data;
-        uint64_t time_at_migration = kvmclock_current_nsec(s);
 
         s->clock_valid = false;
 
-	/* We can't rely on the migrated clock value, just discard it */
-	if (time_at_migration) {
-	        s->clock = time_at_migration;
-	}
-
         data.clock = s->clock;
         data.flags = 0;
         ret = kvm_vm_ioctl(kvm_state, KVM_SET_CLOCK, &data);
-- 
1.8.3.1