On 30.05.2022 17:58, Roger Pau Monné wrote: > On Mon, May 30, 2022 at 05:48:51PM +0200, Jan Beulich wrote: >> Avoid calling the function more than once, thus making sure we won't, >> under any unusual circumstances, attempt to enable XEN_LER late (which >> can't work, for setup_force_cpu_cap() being __init. In turn this then >> allows making the function itself __init, too. >> >> While fiddling with section attributes in this area, also move the two >> involved variables to .data.ro_after_init. >> >> Signed-off-by: Jan Beulich <[email protected]> >> >> --- a/xen/arch/x86/traps.c >> +++ b/xen/arch/x86/traps.c >> @@ -126,11 +126,11 @@ DEFINE_PER_CPU_PAGE_ALIGNED(struct tss_p >> static int debug_stack_lines = 20; >> integer_param("debug_stack_lines", debug_stack_lines); >> >> -static bool opt_ler; >> +static bool __ro_after_init opt_ler; >> boolean_param("ler", opt_ler); >> >> /* LastExceptionFromIP on this hardware. Zero if LER is not in use. */ >> -unsigned int __read_mostly ler_msr; >> +unsigned int __ro_after_init ler_msr; >> >> const unsigned int nmi_cpu; >> >> @@ -2133,7 +2133,7 @@ static void __init set_intr_gate(unsigne >> __set_intr_gate(n, 0, addr); >> } >> >> -static unsigned int calc_ler_msr(void) >> +static unsigned int noinline __init calc_ler_msr(void) >> { >> switch ( boot_cpu_data.x86_vendor ) >> { >> @@ -2171,8 +2171,17 @@ void percpu_traps_init(void) >> if ( !opt_ler ) >> return; >> >> - if ( !ler_msr && (ler_msr = calc_ler_msr()) ) >> + if ( !ler_msr ) >> + { >> + ler_msr = calc_ler_msr(); >> + if ( !ler_msr ) >> + { > > While doing this rework it might make sense to print some message > here, like: "LER option requested but no LBR support available" or > similar IMO.
Hmm, yes, but you look to do so in your series already. Could we leave things silent here (as it always was) until your adding of arch-LBR support, and then taking care of both failure conditions with a single log message? Of course I could add a message here just for you to then (likely) alter it again ... > The rest LGTM: > > Reviewed-by: Roger Pau Monné <[email protected]> Thanks, but I'll wait with applying this. Jan
