From: Vitaly Kuznetsov <vkuznets@redhat.com>
Date: Sat, 28 Jan 2017 19:37:15 +0000 (-0700)
Subject: Drivers: hv: restore TSC page cleanup before kexec
X-Git-Tag: v4.11-rc1~118^2~68
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=5647dbf8f0807a35421bd0232247b02413ef2cab;p=linux.git

Drivers: hv: restore TSC page cleanup before kexec

We need to cleanup the TSC page before doing kexec/kdump or the new kernel
may crash if it tries to use it.

Fixes: 63ed4e0c67df ("Drivers: hv: vmbus: Consolidate all Hyper-V specific clocksource code")
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index d6b018b86c42..b371d0e984a9 100644
--- a/arch/x86/hyperv/hv_init.c
+++ b/arch/x86/hyperv/hv_init.c
@@ -178,6 +178,10 @@ void hyperv_cleanup(void)
 	/* Reset the hypercall page */
 	hypercall_msr.as_uint64 = 0;
 	wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);
+
+	/* Reset the TSC page */
+	hypercall_msr.as_uint64 = 0;
+	wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64);
 }
 EXPORT_SYMBOL_GPL(hyperv_cleanup);