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[bionic:linux-azure-4.15,7/9] x86/Hyper-V: Report crash register data or kmsg before running crash kernel

Message ID 20200616025842.102415-8-marcelo.cerri@canonical.com
State New
Headers show
Series LP:#1875456 - Azure diagnostic/serviceability improvement | expand

Commit Message

Marcelo Henrique Cerri June 16, 2020, 2:58 a.m. UTC 
From: Tianyu Lan <Tianyu.Lan@microsoft.com>

BugLink: http://bugs.launchpad.net/bugs/1875456

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.

Fixes: 81b18bce48af ("Drivers: HV: Send one page worth of kmsg dump over Hyper-V during panic")
Reviewed-by: Michael Kelley <mikelley@microsoft.com>
Signed-off-by: Tianyu Lan <Tianyu.Lan@microsoft.com>
Link: https://lore.kernel.org/r/20200406155331.2105-5-Tianyu.Lan@microsoft.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>
(backported from commit a11589563e96bf262767294b89b25a9d44e7303b)
[mc: fixed context]
Signed-off-by: Marcelo Henrique Cerri <marcelo.cerri@canonical.com>
---
 arch/x86/kernel/cpu/mshyperv.c | 10 ++++++++++
 1 file changed, 10 insertions(+)
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Patch

diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index a06aeb529eda..7d602805bf0b 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -209,6 +209,16 @@  static void __init ms_hyperv_init_platform(void)
 		x86_platform.calibrate_cpu = hv_get_tsc_khz;
 	}
 
+	/*
+	 * 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) {