Hi Stefano,
On 04/04/17 02:09, Stefano Stabellini wrote:
This patch fixes a potential race that could happen when
gic_update_one_lr and vgic_vcpu_inject_irq run simultaneously.
When GIC_IRQ_GUEST_MIGRATING is set, we must make sure that the irq has
been removed from inflight before changing physical affinity, to avoid
concurrent accesses to p->inflight, as vgic_vcpu_inject_irq will take a
different vcpu lock.
Signed-off-by: Stefano Stabellini <sstabell...@kernel.org>
---
xen/arch/arm/gic.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/xen/arch/arm/gic.c b/xen/arch/arm/gic.c
index 9522c6c..de996d9 100644
--- a/xen/arch/arm/gic.c
+++ b/xen/arch/arm/gic.c
@@ -503,6 +503,11 @@ static void gic_update_one_lr(struct vcpu *v, int i)
gic_raise_guest_irq(v, irq, p->priority);
else {
list_del_init(&p->inflight);
+ /* Remove from inflight, then change physical affinity. It
+ * makes sure that when a new interrupt is received on the
+ * next pcpu, inflight is already cleared. No concurrent
+ * accesses to inflight. */
Coding style:
/*
* ...
*/
With that:
Reviewed-by: Julien Grall <julien.gr...@arm.com>
+ smp_wmb();
if ( test_and_clear_bit(GIC_IRQ_GUEST_MIGRATING, &p->status) )
{
struct vcpu *v_target = vgic_get_target_vcpu(v, irq);
Cheers,
--
Julien Grall
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