[Qemu-devel] [PULL 6/6] Revert "kvmclock: Ensure time in migration never goes backward"

[Paolo Bonzini <pbonzini@redhat.com>]

This reverts commit a096b3a6732f846ec57dc28b47ee9435aa0609bf.

This patch caused a hang that was fixed by commit 9b17868 (kvmclock:
Ensure proper env->tsc value for kvmclock_current_nsec calculation,
2014-06-03), and we just had to revert that commit.  Drop this one
too.

Cc: agraf@suse.de
Cc: mtosatti@redhat.com
Cc: qemu-stable@nongnu.org
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 hw/i386/kvm/clock.c | 48 ------------------------------------------------
 1 file changed, 48 deletions(-)

diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c
index feb5fc5..07b9c0e 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"
@@ -35,47 +34,6 @@ 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)
-{
-    CPUState *cpu = first_cpu;
-    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)
@@ -87,15 +45,9 @@ 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);
-- 
1.9.3