From 4c1cd02acb563d9a8a0485e795760e0bb149fe43 Mon Sep 17 00:00:00 2001 From: Stefano Stabellini Date: Tue, 8 Jul 2025 11:32:38 -0700 Subject: [PATCH] xen/x86: introduce MCE_NONFATAL Today, checking for non-fatal MCE errors on AMD is very invasive: it involves a periodic timer interrupting the physical CPU execution at regular intervals. Moreover, when the timer fires, the handler sends an IPI to all physical CPUs. Both these actions are disruptive in terms of latency and deterministic execution times for real-time workloads. They might miss a deadline due to one of these IPIs. Make it possible to disable non-fatal MCE errors checking with a new Kconfig option (MCE_NONFATAL). Signed-off-by: Stefano Stabellini Reviewed-by: Alejandro Vallejo Acked-by: Jan Beulich --- xen/arch/x86/Kconfig | 14 ++++++++++++++ xen/arch/x86/cpu/mcheck/Makefile | 6 +++--- 2 files changed, 17 insertions(+), 3 deletions(-) diff --git a/xen/arch/x86/Kconfig b/xen/arch/x86/Kconfig index 752d5141bb..9ec0fb0bed 100644 --- a/xen/arch/x86/Kconfig +++ b/xen/arch/x86/Kconfig @@ -248,6 +248,20 @@ config X2APIC_MIXED endchoice +config MCE_NONFATAL + bool "Check for non-fatal MCEs" if EXPERT + 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 GUEST bool 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