From c5852a85ed87d963ea5bcfead4f61fc9a276882c Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Fri, 15 Apr 2016 15:50:32 +0200 Subject: [PATCH] x86/hyperv: Avoid reporting bogus NMI status for Gen2 instances [ Upstream commit 1e2ae9ec072f3b7887f456426bc2cf23b80f661a ] Generation2 instances don't support reporting the NMI status on port 0x61, read from there returns 'ff' and we end up reporting nonsensical PCI error (as there is no PCI bus in these instances) on all NMIs: NMI: PCI system error (SERR) for reason ff on CPU 0. Dazed and confused, but trying to continue Fix the issue by overriding x86_platform.get_nmi_reason. Use 'booted on EFI' flag to detect Gen2 instances. Signed-off-by: Vitaly Kuznetsov Cc: Alexander Shishkin Cc: Arnaldo Carvalho de Melo Cc: Cathy Avery Cc: Haiyang Zhang Cc: Jiri Olsa Cc: K. Y. Srinivasan Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: devel@linuxdriverproject.org Link: http://lkml.kernel.org/r/1460728232-31433-1-git-send-email-vkuznets@redhat.com Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/cpu/mshyperv.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c index 20e242ea1bc4..cfc4a966e2b9 100644 --- a/arch/x86/kernel/cpu/mshyperv.c +++ b/arch/x86/kernel/cpu/mshyperv.c @@ -152,6 +152,11 @@ static struct clocksource hyperv_cs = { .flags = CLOCK_SOURCE_IS_CONTINUOUS, }; +static unsigned char hv_get_nmi_reason(void) +{ + return 0; +} + static void __init ms_hyperv_init_platform(void) { /* @@ -191,6 +196,13 @@ static void __init ms_hyperv_init_platform(void) machine_ops.crash_shutdown = hv_machine_crash_shutdown; #endif mark_tsc_unstable("running on Hyper-V"); + + /* + * Generation 2 instances don't support reading the NMI status from + * 0x61 port. + */ + if (efi_enabled(EFI_BOOT)) + x86_platform.get_nmi_reason = hv_get_nmi_reason; } const __refconst struct hypervisor_x86 x86_hyper_ms_hyperv = { -- 2.34.1