On Sun, Jan 31, 2016 at 07:19:35PM +, Mark Cave-Ayland wrote:
> This patch provides support for migration of the PPC guest timebase on non-PPC
> host architectures (i.e those using QEMU's virtual emulated timebase).
>
> Signed-off-by: Mark Cave-Ayland
We shouldn't need an explicit test for a ppc host. Instead we should
never be touching any host-dependent ticks values, only using host
side interfaces which work in realtime units like ns.
Worse, the ppc host variants here will still be wrong if the host has
a different timebase frequency to the guest, which will always be true
for a g3beige (16MHz) on a modern ppc host (512 MHz).
> ---
> hw/ppc/ppc.c | 33 +++--
> 1 file changed, 27 insertions(+), 6 deletions(-)
>
> diff --git a/hw/ppc/ppc.c b/hw/ppc/ppc.c
> index 19f4570..9b80c1d 100644
> --- a/hw/ppc/ppc.c
> +++ b/hw/ppc/ppc.c
> @@ -832,6 +832,15 @@ static void cpu_ppc_set_tb_clk (void *opaque, uint32_t
> freq)
> cpu_ppc_store_purr(cpu, 0xULL);
> }
>
> +static int host_cpu_is_ppc(void)
> +{
> +#if defined(_ARCH_PPC)
> +return -1;
> +#else
> +return 0;
> +#endif
> +}
> +
> static void timebase_pre_save(void *opaque)
> {
> PPCTimebase *tb = opaque;
> @@ -844,11 +853,16 @@ static void timebase_pre_save(void *opaque)
> }
>
> tb->time_of_the_day_ns = qemu_clock_get_ns(QEMU_CLOCK_HOST);
> -/*
> - * tb_offset is only expected to be changed by migration so
> - * there is no need to update it from KVM here
> - */
> -tb->guest_timebase = ticks + first_ppc_cpu->env.tb_env->tb_offset;
> +
> +if (host_cpu_is_ppc()) {
> +/*
> + * tb_offset is only expected to be changed by migration so
> + * there is no need to update it from KVM here
> + */
> +tb->guest_timebase = ticks + first_ppc_cpu->env.tb_env->tb_offset;
> +} else {
> +tb->guest_timebase = cpu_ppc_load_tbl(&first_ppc_cpu->env);
> +}
> }
>
> static int timebase_post_load(void *opaque, int version_id)
> @@ -879,7 +893,14 @@ static int timebase_post_load(void *opaque, int
> version_id)
> NANOSECONDS_PER_SECOND);
> guest_tb = tb_remote->guest_timebase + migration_duration_tb;
>
> -tb_off_adj = guest_tb - cpu_get_host_ticks();
> +if (host_cpu_is_ppc()) {
> +/* Hardware timebase */
> +tb_off_adj = guest_tb - cpu_get_host_ticks();
> +} else {
> +/* Software timebase */
> +tb_off_adj = guest_tb -
> muldiv64(qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL),
> + freq, get_ticks_per_sec());
> +}
>
> tb_off = first_ppc_cpu->env.tb_env->tb_offset;
> trace_ppc_tb_adjust(tb_off, tb_off_adj, tb_off_adj - tb_off,
--
David Gibson| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
signature.asc
Description: PGP signature
