lkml.org 
[lkml]   [2020]   [Mar]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRE: [PATCH 4/4] x86/Hyper-V: Report crash register data or ksmg before running crash kernel
Date
From: ltykernel@gmail.com <ltykernel@gmail.com>  Sent: Tuesday, March 17, 2020 6:25 AM
>
> Hyper-V expects to get crash register data or kmsg via crash
> enlightenment when guest crash happens. crash_kexec_post_notifiers
> is default to be false and crash kernel runs before calling hv
> panic callback and dumping kmsg. In this case, Hyper-V doesn't
> get crash register data or kmsg from guest. Set crash_kexec_post
> _notifiers to be true for Hyper-V VM and fix it.

Suggested wording tweaks:

We want to notify Hyper-V when a Linux guest VM crash occurs, so
there is a record of the crash even when kdump is enabled. But
crash_kexec_post_notifiers defaults to "false", so the kdump kernel
runs before the notifiers and Hyper-V never gets notified. Fix this by
always setting crash_kexec_post_notifiers to be true for Hyper-V VMs.

>
> Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
> ---
> arch/x86/kernel/cpu/mshyperv.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
> index caa032ce3fe3..5e296a7e6036 100644
> --- a/arch/x86/kernel/cpu/mshyperv.c
> +++ b/arch/x86/kernel/cpu/mshyperv.c
> @@ -263,6 +263,16 @@ static void __init ms_hyperv_init_platform(void)
> cpuid_eax(HYPERV_CPUID_NESTED_FEATURES);
> }
>
> + /*
> + * Hyper-V expects to get crash register data or kmsg when
> + * crash enlightment is available and system crashes. Set
> + * crash_kexec_post_notifiers to be true to make sure that
> + * calling crash enlightment interface before running kdump
> + * kernel.
> + */
> + if (ms_hyperv.misc_features & HV_FEATURE_GUEST_CRASH_MSR_AVAILABLE)
> + crash_kexec_post_notifiers = true;
> +
> #ifdef CONFIG_X86_LOCAL_APIC
> if (ms_hyperv.features & HV_X64_ACCESS_FREQUENCY_MSRS &&
> ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE) {
> --
> 2.14.5

\
 
 \ /
  Last update: 2020-03-19 01:53    [W:0.211 / U:12.636 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site