A GICv3 hardware implementation can be implemented in several parts that
communicate with each other (think multi-socket systems).
To make sure that critical settings have arrived at all endpoints, some
bits are tracked using the RWP bit in the GICD_CTLR register, which
signals whether a register write is still in progress.
However this only applies to *some* registers, namely the bits in the
GICD_ICENABLER (disabling interrupts) and some bits in the GICD_CTLR
register (cf. Arm IHI 0069D, 8.9.4: RWP, bit[31]).
But our gicv3_poke_irq() was always polling this bit before returning,
resulting in pointless MMIO reads for many registers.
Add an option to gicv3_poke_irq() to state whether we want to wait for
this bit and use it accordingly to match the spec.
Signed-off-by: Andre Przywara <andre.przywara@xxxxxxxxxx>
---
Changelog RFC ... v1:
- new patch
xen/arch/arm/gic-v3.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/xen/arch/arm/gic-v3.c b/xen/arch/arm/gic-v3.c
index 3e381d031b..44dfba2267 100644
--- a/xen/arch/arm/gic-v3.c
+++ b/xen/arch/arm/gic-v3.c
@@ -428,9 +428,9 @@ static void gicv3_dump_state(const struct vcpu *v)
}
}
-static void gicv3_poke_irq(struct irq_desc *irqd, u32 offset)
+static void gicv3_poke_irq(struct irq_desc *irqd, u32 offset, bool
wait_for_rwp)
{
- u32 mask = 1 << (irqd->irq % 32);
+ u32 mask = 1U << (irqd->irq % 32);
