From: Vitaly Kuznetsov <vkuznets@redhat.com>
Date: Wed, 7 Dec 2016 09:16:27 +0000 (-0800)
Subject: hv: don't reset hv_context.tsc_page on crash
X-Git-Tag: C0P2-H0.0--20200415~9997
X-Git-Url: https://git.somdevices.com/?a=commitdiff_plain;h=664f72a17f2c072175a0083388f315f811ff1acb;p=linux.git

hv: don't reset hv_context.tsc_page on crash

commit 56ef6718a1d8d77745033c5291e025ce18504159 upstream.

It may happen that secondary CPUs are still alive and resetting
hv_context.tsc_page will cause a consequent crash in read_hv_clock_tsc()
as we don't check for it being not NULL there. It is safe as we're not
freeing this page anyways.

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/drivers/hv/hv.c b/drivers/hv/hv.c
index a2567a4be1a8..6e49a4dd99c0 100644
--- a/drivers/hv/hv.c
+++ b/drivers/hv/hv.c
@@ -309,9 +309,10 @@ void hv_cleanup(bool crash)
 
 		hypercall_msr.as_uint64 = 0;
 		wrmsrl(HV_X64_MSR_REFERENCE_TSC, hypercall_msr.as_uint64);
-		if (!crash)
+		if (!crash) {
 			vfree(hv_context.tsc_page);
-		hv_context.tsc_page = NULL;
+			hv_context.tsc_page = NULL;
+		}
 	}
 #endif
 }