Re: [PATCH 2/2] x86/tsc: Fix UV TSC initialization

[Mike Travis]

On 10/1/2018 11:22 PM, Thomas Gleixner wrote:
> On Mon, 1 Oct 2018, Mike Travis wrote:
>
> > Fix regression introduced by
> >
> > commit cf7a63ef4e02 ("x86/tsc: Calibrate tsc only once")
> >
> > as it changed setup_arch() so that it now calls tsc_early_init() before
> > acpi_boot_table_init() which is a necessary step, in the case of UV
> > systems, to inform tsc_sanitize_first_cpu() that we're on a platform
> > with async TSC resets as documented in
> >
> > commit 341102c3ef29 ("x86/tsc: Add option that TSC on Socket 0 being non-zero is valid")
> >
> > Fix by skipping tsc_early_init() on UV systems and let TSC initialization
> > take place later in tsc_init().
> >
> > Fixes: cf7a63ef4e02 ("x86/tsc: Calibrate tsc only once")
> > Signed-off-by: Mike Travis <mike.travis@xxxxxxx>
> > Signed-off-by: Hedi Berriche <hedi.berriche@xxxxxxx>
>
> See previous mail.
>
> > Reviewed-by: Russ Anderson <rja@xxxxxxx>
> > Reviewed-by: Dimitri Sivanich <sivanich@xxxxxxx>
> > ---
> >   arch/x86/kernel/setup.c |    6 +++++-
> >   1 file changed, 5 insertions(+), 1 deletion(-)
> >
> > --- linux.orig/arch/x86/kernel/setup.c
> > +++ linux/arch/x86/kernel/setup.c
> > @@ -117,6 +117,7 @@
> >   #include <asm/microcode.h>
> >   #include <asm/kaslr.h>
> >   #include <asm/unwind.h>
> > +#include <asm/uv/uv.h>
> >   
> >   /*
> >    * max_low_pfn_mapped: highest direct mapped pfn under 4GB
> > @@ -1015,7 +1016,10 @@ void __init setup_arch(char **cmdline_p)
> >   	 */
> >   	init_hypervisor_platform();
> >   
> > -	tsc_early_init();
> > +	/* UV TSC multi-chassis synchronization already set, don't change it */
> > +	if (!is_early_uv_system())
> > +		tsc_early_init();
>
> tsc_early_init() has already a check which makes it not invoke the
> calibration code, so please put your uv check into that.

Will do, thanks.

> Thanks,
>
> 	tglx