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.
Jan
> 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
