From: Paolo Bonzini <pbonzini@redhat.com>
Date: Wed, 26 Apr 2017 14:56:26 +0000 (+0200)
Subject: kvm: async_pf: fix rcu_irq_enter() with irqs enabled
X-Git-Tag: release-20171130_firefly~4^2~100^2~1^2~4^2~63
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=a8bbdf1921fde7643eb22b508acc2fa0239021bf;p=firefly-linux-kernel-4.4.55.git

kvm: async_pf: fix rcu_irq_enter() with irqs enabled

commit bbaf0e2b1c1b4f88abd6ef49576f0efb1734eae5 upstream.

native_safe_halt enables interrupts, and you just shouldn't
call rcu_irq_enter() with interrupts enabled.  Reorder the
call with the following local_irq_disable() to respect the
invariant.

Reported-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 47190bd399e7..cec49ecf5f31 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -161,8 +161,8 @@ void kvm_async_pf_task_wait(u32 token)
 			 */
 			rcu_irq_exit();
 			native_safe_halt();
-			rcu_irq_enter();
 			local_irq_disable();
+			rcu_irq_enter();
 		}
 	}
 	if (!n.halted)