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 694d801bf606736fb5b54a74b225fa229c7f5ac4..b8ba6e4a27e4102bd36a6445ec4b503be990d62d 100644 (file)
--- 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;
        }
 }