From: Michael Kelley <mikelley@microsoft.com>
To: "ltykernel@gmail.com" <ltykernel@gmail.com>,
KY Srinivasan <kys@microsoft.com>,
Haiyang Zhang <haiyangz@microsoft.com>,
Stephen Hemminger <sthemmin@microsoft.com>,
Wei Liu <liuwe@microsoft.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"mingo@redhat.com" <mingo@redhat.com>,
"bp@alien8.de" <bp@alien8.de>, "hpa@zytor.com" <hpa@zytor.com>,
"x86@kernel.org" <x86@kernel.org>
Cc: Tianyu Lan <Tianyu.Lan@microsoft.com>,
"linux-hyperv@vger.kernel.org" <linux-hyperv@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
vkuznets <vkuznets@redhat.com>
Subject: RE: [PATCH 4/4] x86/Hyper-V: Report crash register data or ksmg before running crash kernel
Date: Thu, 19 Mar 2020 00:51:15 +0000 [thread overview]
Message-ID: <MW2PR2101MB105299CD9F7920E09A44BDCCD7F40@MW2PR2101MB1052.namprd21.prod.outlook.com> (raw)
In-Reply-To: <20200317132523.1508-5-Tianyu.Lan@microsoft.com>
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
next prev parent reply other threads:[~2020-03-19 0:51 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-17 13:25 [PATCH 0/4] x86/Hyper-V: Panic code path fixes ltykernel
2020-03-17 13:25 ` [PATCH 0/4] x86/Hyper-V: Unload vmbus channel in hv panic callback ltykernel
2020-03-17 17:35 ` Wei Liu
2020-03-19 8:24 ` Tianyu Lan
2020-03-18 15:58 ` Vitaly Kuznetsov
2020-03-19 0:33 ` Michael Kelley
2020-03-19 8:03 ` Vitaly Kuznetsov
2020-03-19 15:06 ` Michael Kelley
2020-03-19 8:03 ` Tianyu Lan
2020-03-17 13:25 ` [PATCH 2/4] x86/Hyper-V: Free hv_panic_page when fail to register kmsg dump ltykernel
2020-03-17 17:36 ` Wei Liu
2020-03-19 8:12 ` Tianyu Lan
2020-03-19 0:38 ` Michael Kelley
2020-03-17 13:25 ` [PATCH 3/4] x86/Hyper-V: Trigger crash enlightenment only once during system crash ltykernel
2020-03-19 0:45 ` Michael Kelley
2020-03-17 13:25 ` [PATCH 4/4] x86/Hyper-V: Report crash register data or ksmg before running crash kernel ltykernel
2020-03-19 0:51 ` Michael Kelley [this message]
2020-03-19 0:57 ` [PATCH 0/4] x86/Hyper-V: Panic code path fixes Michael Kelley
2020-03-19 14:08 ` Tianyu Lan
2020-03-19 15:14 ` Michael Kelley
2020-03-19 16:07 ` Michael Kelley
2020-03-20 2:21 ` Tianyu Lan
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