| Message ID | 20140603051630.GA2289@amt.cnet |
|---|---|
| State | New |
| Headers | show |
> Can you give this patch a try? Should read the guest TSC values after > stopping the VM. Yes, this patch fixes that. Thanks,
Il 03/06/2014 07:16, Marcelo Tosatti ha scritto: > On Mon, Jun 02, 2014 at 10:31:44PM +0200, Marcin Gibuła wrote: >>> + cpu_physical_memory_read(kvmclock_struct_pa, &time, sizeof(time)); >>> + >>> + delta = migration_tsc - time.tsc_timestamp; >> >> Hi, >> >> when I was testing live storage migration with libvirt I found out >> that this patch can cause virtual machine to hang when completing >> mirror job. >> >> This is (probably) because kvmclock_current_nsec() is called twice >> in a row and on second call time.tsc_timestamp is larger than >> migration_tsc. This causes delta to be huge and sets timer to >> invalid value. >> >> The double call happens when switching from old to new disk >> (pivoting in libvirt's nomenclature). >> >> Example values: >> >> First call: migration_tsc: 12052203518652476, time_tsc: >> 12052203301565676, delta 108543400 >> >> Second call: migration_tsc: 12052203518652476, time_tsc: >> 12052204478600322, delta 9223372036374801885 >> >> Perhaps it is worth adding: >> >> if (time.tsc_timestamp > migration_tsc) { >> return 0; >> } >> >> there? Untested though... > > Hi Marcin, > > Can you give this patch a try? Should read the guest TSC values after > stopping the VM. > > > diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c > index 6f4ed28a..bef2504 100644 > --- a/hw/i386/kvm/clock.c > +++ b/hw/i386/kvm/clock.c > @@ -17,6 +17,7 @@ > #include "qemu/host-utils.h" > #include "sysemu/sysemu.h" > #include "sysemu/kvm.h" > +#include "sysemu/cpus.h" > #include "hw/sysbus.h" > #include "hw/kvm/clock.h" > > @@ -65,6 +66,7 @@ static uint64_t kvmclock_current_nsec(KVMClockState *s) > > cpu_physical_memory_read(kvmclock_struct_pa, &time, sizeof(time)); > > + assert(time.tsc_timestamp <= migration_tsc); > delta = migration_tsc - time.tsc_timestamp; > if (time.tsc_shift < 0) { > delta >>= -time.tsc_shift; > @@ -123,6 +125,8 @@ static void kvmclock_vm_state_change(void *opaque, int running, > if (s->clock_valid) { > return; > } > + > + cpu_synchronize_all_states(); > ret = kvm_vm_ioctl(kvm_state, KVM_GET_CLOCK, &data); > if (ret < 0) { > fprintf(stderr, "KVM_GET_CLOCK failed: %s\n", strerror(ret)); > Can you send it with a real commit message? Paolo
diff --git a/hw/i386/kvm/clock.c b/hw/i386/kvm/clock.c index 6f4ed28a..bef2504 100644 --- a/hw/i386/kvm/clock.c +++ b/hw/i386/kvm/clock.c @@ -17,6 +17,7 @@ #include "qemu/host-utils.h" #include "sysemu/sysemu.h" #include "sysemu/kvm.h" +#include "sysemu/cpus.h" #include "hw/sysbus.h" #include "hw/kvm/clock.h" @@ -65,6 +66,7 @@ static uint64_t kvmclock_current_nsec(KVMClockState *s) cpu_physical_memory_read(kvmclock_struct_pa, &time, sizeof(time)); + assert(time.tsc_timestamp <= migration_tsc); delta = migration_tsc - time.tsc_timestamp; if (time.tsc_shift < 0) { delta >>= -time.tsc_shift; @@ -123,6 +125,8 @@ static void kvmclock_vm_state_change(void *opaque, int running, if (s->clock_valid) { return; } + + cpu_synchronize_all_states(); ret = kvm_vm_ioctl(kvm_state, KVM_GET_CLOCK, &data); if (ret < 0) { fprintf(stderr, "KVM_GET_CLOCK failed: %s\n", strerror(ret));