irqchip/gic-v3: Make sure read from ICC_IAR1_EL1 is visible on redestributor

The ARM GICv3 specification mentions the need for dsb after a read
from the ICC_IAR1_EL1 register:

	4.1.1 Physical CPU Interface:
	The effects of reading ICC_IAR0_EL1 and ICC_IAR1_EL1
	on the state of a returned INTID are not guaranteed
	to be visible until after the execution of a DSB.

Not having this could result in missed interrupts, so let's add the
required barrier.

[Marc: fixed commit message]

Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Tirumalesh Chalamarla <tchalamarla@caviumnetworks.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/arch/arm64/include/asm/arch_gicv3.h b/arch/arm64/include/asm/arch_gicv3.h
index 2731d3b25ed2..8ec88e5b290f 100644
--- a/arch/arm64/include/asm/arch_gicv3.h
+++ b/arch/arm64/include/asm/arch_gicv3.h
@@ -103,6 +103,7 @@ static inline u64 gic_read_iar_common(void)
         u64 irqstat;
 
         asm volatile("mrs_s %0, " __stringify(ICC_IAR1_EL1) : "=r" (irqstat));
+        dsb(sy);
         return irqstat;
 }