On Tue, 8 Jul 2025, Jan Beulich wrote:
> On 08.07.2025 12:25, Alejandro Vallejo wrote:
> > On Tue Jul 8, 2025 at 2:07 AM CEST, Stefano Stabellini wrote:
> >> --- a/xen/arch/x86/Kconfig.cpu
> >> +++ b/xen/arch/x86/Kconfig.cpu
> >> @@ -10,6 +10,21 @@ config AMD
> >> May be turned off in builds targetting other vendors. Otherwise,
> >> must be enabled for Xen to work suitably on AMD platforms.
> >>
> >> +config AMD_MCE_NONFATAL
> >> + bool "Check for non-fatal MCEs on AMD CPUs"
> >> + default y
> >> + depends on AMD
> >> + help
> >> + Check for non-fatal MCE errors.
> >> +
> >> + When this option is on (default), Xen regularly checks for
> >> + non-fatal MCEs potentially occurring on all physical CPUs. The
> >> + checking is done via timers and IPI interrupts, which is
> >> + acceptable in most configurations, but not for real-time.
> >> +
> >> + Turn this option off if you plan on deploying real-time workloads
> >> + on Xen.
> >> +
> >
> > This being in the CPU vendor submenu seems off. I'd expect only a list of
> > silicon vendors here. I think it ought to be in the regular Kconfig file.
>
> Whether in this file or the regular one is up for discussion, but yes,
> definitely not inside the vendor menu.
>
> >> --- a/xen/arch/x86/cpu/mcheck/amd_nonfatal.c
> >> +++ b/xen/arch/x86/cpu/mcheck/amd_nonfatal.c
> >> @@ -191,7 +191,8 @@ static void cf_check mce_amd_work_fn(void *data)
> >>
> >> void __init amd_nonfatal_mcheck_init(struct cpuinfo_x86 *c)
> >> {
> >> - if (!(c->x86_vendor & (X86_VENDOR_AMD | X86_VENDOR_HYGON)))
> >> + if ( !IS_ENABLED(CONFIG_AMD_MCE_NONFATAL) ||
> >> + (!(c->x86_vendor & (X86_VENDOR_AMD | X86_VENDOR_HYGON))) )
> >> return;
> >>
> >> /* Assume we are on K8 or newer AMD or Hygon CPU here */
> >
> > It can be made more general to remove more code. What do you think of
> > removing
> > all non-fatals and getting rid of the initcall altogether?
>
> I think such a more general approach would be quite a bit better.
I am fine with that, actually better to remove the code then to leave it
around and do nothing.
> > diff --git a/xen/arch/x86/Kconfig.cpu b/xen/arch/x86/Kconfig.cpu
> > index 5fb18db1aa..a4b892a1aa 100644
> > --- a/xen/arch/x86/Kconfig.cpu
> > +++ b/xen/arch/x86/Kconfig.cpu
> > @@ -10,6 +10,20 @@ config AMD
> > May be turned off in builds targetting other vendors.
> > Otherwise,
> > must be enabled for Xen to work suitably on AMD platforms.
> >
> > +config MCE_NONFATAL
> > + bool "Check for non-fatal MCEs"
> > + default y
> > + help
> > + Check for non-fatal MCE errors.
> > +
> > + When this option is on (default), Xen regularly checks for
> > + non-fatal MCEs potentially occurring on all physical CPUs. The
> > + checking is done via timers and IPI interrupts, which is
> > + acceptable in most configurations, but not for real-time.
> > +
> > + Turn this option off if you plan on deploying real-time
> > workloads
> > + on Xen.
> > +
> > config INTEL
> > bool "Support Intel CPUs"
> > default y
> > diff --git a/xen/arch/x86/cpu/mcheck/Makefile
> > b/xen/arch/x86/cpu/mcheck/Makefile
> > index e6cb4dd503..c70b441888 100644
> > --- a/xen/arch/x86/cpu/mcheck/Makefile
> > +++ b/xen/arch/x86/cpu/mcheck/Makefile
> > @@ -1,12 +1,12 @@
> > -obj-$(CONFIG_AMD) += amd_nonfatal.o
> > +obj-$(filter $(CONFIG_AMD),$(CONFIG_MCE_NONFATAL)) += amd_nonfatal.o
> > obj-$(CONFIG_AMD) += mce_amd.o
> > obj-y += mcaction.o
> > obj-y += barrier.o
> > -obj-$(CONFIG_INTEL) += intel-nonfatal.o
> > +obj-$(filter $(CONFIG_INTEL),$(CONFIG_MCE_NONFATAL)) +=
> > intel-nonfatal.o
> > obj-y += mctelem.o
> > obj-y += mce.o
> > obj-y += mce-apei.o
> > obj-$(CONFIG_INTEL) += mce_intel.o
> > -obj-y += non-fatal.o
> > +obj-$(CONFIG_MCE_NONFATAL) += non-fatal.o
> > obj-y += util.o
> > obj-y += vmce.o
> >
> > ... with the Kconfig option probably in the regular x86 Kconfig rather than
> > Kconfig.cpu
> >
> > Thoughts?
> >
> > Cheers,
> > Alejandro
>
