Patch "hv: don't reset hv_context.tsc_page on crash" has been added to the 4.10-stable tree

Patch "hv: don't reset hv_context.tsc_page on crash" has been added to the 4.10-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    hv: don't reset hv_context.tsc_page on crash

to the 4.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     hv-don-t-reset-hv_context.tsc_page-on-crash.patch
and it can be found in the queue-4.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 56ef6718a1d8d77745033c5291e025ce18504159 Mon Sep 17 00:00:00 2001
From: Vitaly Kuznetsov <vkuznets@redhat.com>
Date: Wed, 7 Dec 2016 01:16:27 -0800
Subject: hv: don't reset hv_context.tsc_page on crash

From: Vitaly Kuznetsov <vkuznets@redhat.com>

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>

---
 drivers/hv/hv.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- 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
 }


Patches currently in stable-queue which might be from vkuznets@redhat.com are

queue-4.10/hv-init-percpu_list-in-hv_synic_alloc.patch
queue-4.10/drivers-hv-vmbus-raise-retry-wait-limits-in-vmbus_post_msg.patch
queue-4.10/hv-allocate-synic-pages-for-all-present-cpus.patch
queue-4.10/hv-don-t-reset-hv_context.tsc_page-on-crash.patch