[PATCH v2 08/10] irqchip/gic-v5: Invalidate ITS device cache before freeing ITT

[Sascha Bischoff <sascha.bischoff@arm.com>]

A cached device table entry can still reference the ITT after its
memory is freed via kfree(), even if the DTE has been marked as
invalid. Once the memory has been released, it could be reallocated,
and it would be unfortunate for the hardware to interpret this as a
valid ITT.

Invalidate the device cache and wait for completion before freeing the
ITT during device teardown.

Fixes: 57d72196dfc85 ("irqchip/gic-v5: Add GICv5 ITS support")
Acked-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Signed-off-by: Sascha Bischoff <sascha.bischoff@arm.com>
---
 drivers/irqchip/irq-gic-v5-its.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/irqchip/irq-gic-v5-its.c b/drivers/irqchip/irq-gic-v5-its.c
index 8628de326f28d..4de07bbdc4923 100644
--- a/drivers/irqchip/irq-gic-v5-its.c
+++ b/drivers/irqchip/irq-gic-v5-its.c
@@ -556,6 +556,7 @@ static int gicv5_its_device_unregister(struct gicv5_its_chip_data *its,
 				       struct gicv5_its_dev *its_dev)
 {
 	__le64 *dte;
+	int ret;
 
 	dte = gicv5_its_devtab_get_dte_ref(its, its_dev->device_id, false);
 
@@ -568,9 +569,10 @@ static int gicv5_its_device_unregister(struct gicv5_its_chip_data *its,
 	/* Zero everything - make it clear that this is an invalid entry */
 	its_write_table_entry(its, dte, 0);
 
+	ret = gicv5_its_device_cache_inv(its, its_dev);
 	gicv5_its_free_itt(its_dev);
 
-	return gicv5_its_device_cache_inv(its, its_dev);
+	return ret;
 }
 
 /*

-- 
2.34.1