linux-kernel - [PATCH 2/2] Drivers: hv: restore TSC page cleanup before kexec

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Message-Id: <20170125131755.21652-3-vkuznets@redhat.com>
Date:   Wed, 25 Jan 2017 14:17:55 +0100
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     devel@...uxdriverproject.org
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        "K. Y. Srinivasan" <kys@...rosoft.com>,
        Haiyang Zhang <haiyangz@...rosoft.com>,
        Stephen Hemminger <sthemmin@...rosoft.com>
Subject: [PATCH 2/2] 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@...hat.com>
---
 arch/x86/hyperv/hv_init.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/x86/hyperv/hv_init.c b/arch/x86/hyperv/hv_init.c
index d6b018b..b371d0e 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);
 
-- 
2.9.3