linux-kernel - [PATCH 3.16.y-ckt 071/180] x86/xen: don't reset vcpu

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Date:	Wed,  3 Feb 2016 22:31:17 +0000
From:	Luis Henriques <luis.henriques@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Charles Ouyang <ouyangzhaowei@...wei.com>,
	David Vrabel <david.vrabel@...rix.com>,
	Luis Henriques <luis.henriques@...onical.com>
Subject: [PATCH 3.16.y-ckt 071/180] x86/xen: don't reset vcpu_info on a cancelled suspend

3.16.7-ckt24 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: "Ouyang Zhaowei (Charles)" <ouyangzhaowei@...wei.com>

commit 6a1f513776b78c994045287073e55bae44ed9f8c upstream.

On a cancelled suspend the vcpu_info location does not change (it's
still in the per-cpu area registered by xen_vcpu_setup()).  So do not
call xen_hvm_init_shared_info() which would make the kernel think its
back in the shared info.  With the wrong vcpu_info, events cannot be
received and the domain will hang after a cancelled suspend.

Signed-off-by: Charles Ouyang <ouyangzhaowei@...wei.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@...cle.com>
Signed-off-by: David Vrabel <david.vrabel@...rix.com>
Signed-off-by: Luis Henriques <luis.henriques@...onical.com>
---
 arch/x86/xen/suspend.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/xen/suspend.c b/arch/x86/xen/suspend.c
index c4df9dbd63b7..2277cc8965fe 100644
--- a/arch/x86/xen/suspend.c
+++ b/arch/x86/xen/suspend.c
@@ -32,7 +32,8 @@ static void xen_hvm_post_suspend(int suspend_cancelled)
 {
 #ifdef CONFIG_XEN_PVHVM
 	int cpu;
-	xen_hvm_init_shared_info();
+	if (!suspend_cancelled)
+	    xen_hvm_init_shared_info();
 	xen_callback_vector();
 	xen_unplug_emulated_devices();
 	if (xen_feature(XENFEAT_hvm_safe_pvclock)) {