From: Jaeyong Yoo <jaeyong.yoo@samsung.com>
Date: Wed, 22 May 2013 02:34:18 +0000 (+0000)
Subject: xen/arm: Disable interrupts for the entire duration of the context switch
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~6793
X-Git-Url: https://dgit.raspbian.org/%22http://www.example.com/cgi/success//%22http:/www.example.com/cgi/success/?a=commitdiff_plain;h=9f5179a4ecafd9a15e0a066e0f935ded681bf997;p=xen.git

xen/arm: Disable interrupts for the entire duration of the context switch

Not just while saving state. Otherwise there is a race between interrupts
arriving and updating the LR state and gic_restore_state overwriting them with
the saved state.

With this change we no longer need to disable interrupts in gic_restore_state.

Signed-off-by: Jaeyong Yoo <jaeyong.yoo@samsung.com>
Acked-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
[ ijc -- rewrote commit message ]
---

diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index 9ca44eaa4e..ee12b5f08f 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -226,10 +226,10 @@ static void schedule_tail(struct vcpu *prev)
 {
     ctxt_switch_from(prev);
 
-    local_irq_enable();
-
     ctxt_switch_to(current);
 
+    local_irq_enable();
+
     if ( prev != current )
         update_runstate_area(current);
 }
diff --git a/xen/arch/arm/gic.c b/xen/arch/arm/gic.c
index 30bf8d1e99..d9940ead05 100644
--- a/xen/arch/arm/gic.c
+++ b/xen/arch/arm/gic.c
@@ -93,11 +93,9 @@ void gic_restore_state(struct vcpu *v)
     if ( is_idle_vcpu(v) )
         return;
 
-    spin_lock_irq(&gic.lock);
     this_cpu(lr_mask) = v->arch.lr_mask;
     for ( i=0; i<nr_lrs; i++)
         GICH[GICH_LR + i] = v->arch.gic_lr[i];
-    spin_unlock_irq(&gic.lock);
     GICH[GICH_APR] = v->arch.gic_apr;
     GICH[GICH_HCR] = GICH_HCR_EN;
     isb();