[Xen-changelog] [xen stable-4.6] xen/arm: gic-v3: Make sure read from ICC_IAR1_EL1 is visible on the redistributor

[patchbot@xxxxxxx]

commit 40837a38ef39b1706cec2d09d5d248494ccd2909
Author:     Julien Grall <julien.grall@xxxxxxx>
AuthorDate: Wed Jan 18 18:54:08 2017 +0000
Commit:     Stefano Stabellini <sstabellini@xxxxxxxxxx>
CommitDate: Wed Jan 18 13:38:32 2017 -0800

    xen/arm: gic-v3: Make sure read from ICC_IAR1_EL1 is visible on the 
redistributor
    
    "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".
    
    Because of the GIC is an external component, a dsb sy is required.
    Without it the sysreg read may not have been made visible on the
    redistributor.
    
    Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
    Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
---
 xen/arch/arm/gic-v3.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/gic-v3.c b/xen/arch/arm/gic-v3.c
index d1db1ce..36ed707 100644
--- a/xen/arch/arm/gic-v3.c
+++ b/xen/arch/arm/gic-v3.c
@@ -455,7 +455,11 @@ static void gicv3_dir_irq(struct irq_desc *irqd)
 
 static unsigned int gicv3_read_irq(void)
 {
-    return READ_SYSREG32(ICC_IAR1_EL1);
+    unsigned int irq = READ_SYSREG32(ICC_IAR1_EL1);
+
+    dsb(sy);
+
+    return irq;
 }
 
 static inline uint64_t gicv3_mpidr_to_affinity(int cpu)
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.6

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