From: Gleb Natapov <gleb@redhat.com>
Date: Wed, 4 Apr 2012 12:30:33 +0000 (+0300)
Subject: KVM: Resolve RCU vs. async page fault problem
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=e08759215b7dcb7111e94f0f96918dd98e86ca6b;p=linux-beck.git

KVM: Resolve RCU vs. async page fault problem

"Page ready" async PF can kick vcpu out of idle state much like IRQ.
We need to tell RCU about this.

Reported-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
---

diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 694d801bf606..b8ba6e4a27e4 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -38,6 +38,7 @@
 #include <asm/traps.h>
 #include <asm/desc.h>
 #include <asm/tlbflush.h>
+#include <asm/idle.h>
 
 static int kvmapf = 1;
 
@@ -253,7 +254,10 @@ do_async_page_fault(struct pt_regs *regs, unsigned long error_code)
 		kvm_async_pf_task_wait((u32)read_cr2());
 		break;
 	case KVM_PV_REASON_PAGE_READY:
+		rcu_irq_enter();
+		exit_idle();
 		kvm_async_pf_task_wake((u32)read_cr2());
+		rcu_irq_exit();
 		break;
 	}
 }