The GICv3 driver executes a DSB barrier before sending an IPI, which
ensures that memory accesses have completed. This removes the need to
enforce ordering with respect to stats_reset() in the IPI handler.
For GICv2, we still need the DMB to ensure ordering between the read of the
GICC_IAR MMIO register and the read from the acked array. It also matches
what the Linux GICv2 driver does in gic_handle_irq().
Reviewed-by: Eric Auger <eric.auger@xxxxxxxxxx>
Signed-off-by: Alexandru Elisei <alexandru.elisei@xxxxxxx>
---
arm/gic.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/arm/gic.c b/arm/gic.c
index 1c9f4a01b6e4..d25529dd8b79 100644
--- a/arm/gic.c
+++ b/arm/gic.c
@@ -60,7 +60,6 @@ static void stats_reset(void)
bad_sender[i] = -1;
bad_irq[i] = -1;
}
- smp_wmb();
}
static void check_acked(const char *testname, cpumask_t *mask)
@@ -150,7 +149,13 @@ static void ipi_handler(struct pt_regs *regs __unused)
if (irqnr != GICC_INT_SPURIOUS) {
gic_write_eoir(irqstat);
- smp_rmb(); /* pairs with wmb in stats_reset */
+ /*
+ * Make sure data written before the IPI was triggered is
+ * observed after the IAR is read. Pairs with the smp_wmb
+ * when sending the IPI.
+ */
+ if (gic_version() == 2)
+ smp_rmb();
++acked[smp_processor_id()];
check_ipi_sender(irqstat);
check_irqnr(irqnr);
--
2.29.2
