[PATCH v2 13/36] irqchip/gic-v4.1: Don't use the VPE proxy if RVPEID is set

Marc Zyngier
2019-10-27T14:44:34Z

The infamous VPE proxy device isn't used with GICv4.1 because:
- we can invalidate any LPI from the DirectLPI MMIO interface
- the ITS and redistributors understand the life cycle of
the doorbell, so we don't need to enable/disable it all
the time

So let's escape early from the proxy related functions.

Signed-off-by: Marc Zyngier <maz@kernel.org>
---
drivers/irqchip/irq-gic-v3-its.c | 23 ++++++++++++++++++++++-
1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 220d490d516e..999e61a9b2c3 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -3069,7 +3069,7 @@ static const struct irq_domain_ops its_domain_ops = {
/*
* This is insane.
*
- * If a GICv4 doesn't implement Direct LPIs (which is extremely
+ * If a GICv4.0 doesn't implement Direct LPIs (which is extremely
* likely), the only way to perform an invalidate is to use a fake
* device to issue an INV command, implying that the LPI has first
* been mapped to some event on that device. Since this is not exactly
@@ -3077,9 +3077,18 @@ static const struct irq_domain_ops its_domain_ops = {
* only issue an UNMAP if we're short on available slots.
*
* Broken by design(tm).
+ *
+ * GICv4.1 actually mandates that we're able to invalidate by writing to a
+ * MMIO register. It doesn't implement the whole of DirectLPI, but that's
+ * good enough. And most of the time, we don't even have to invalidate
+ * anything, so that's actually pretty good!
*/
static void its_vpe_db_proxy_unmap_locked(struct its_vpe *vpe)
{
+ /* GICv4.1 doesn't use a proxy, so nothing to do here */
+ if (gic_rdists->has_rvpeid)
+ return;
+
/* Already unmapped? */
if (vpe->vpe_proxy_event == -1)
return;
@@ -3102,6 +3111,10 @@ static void its_vpe_db_proxy_unmap_locked(struct its_vpe *vpe)

static void its_vpe_db_proxy_unmap(struct its_vpe *vpe)
{
+ /* GICv4.1 doesn't use a proxy, so nothing to do here */
+ if (gic_rdists->has_rvpeid)
+ return;
+
if (!gic_rdists->has_direct_lpi) {
unsigned long flags;

@@ -3113,6 +3126,10 @@ static void its_vpe_db_proxy_unmap(struct its_vpe *vpe)

static void its_vpe_db_proxy_map_locked(struct its_vpe *vpe)
{
+ /* GICv4.1 doesn't use a proxy, so nothing to do here */
+ if (gic_rdists->has_rvpeid)
+ return;
+
/* Already mapped? */
if (vpe->vpe_proxy_event != -1)
return;
@@ -3135,6 +3152,10 @@ static void its_vpe_db_proxy_move(struct its_vpe *vpe, int from, int to)
unsigned long flags;
struct its_collection *target_col;

+ /* GICv4.1 doesn't use a proxy, so nothing to do here */
+ if (gic_rdists->has_rvpeid)
+ return;
+
if (gic_rdists->has_direct_lpi) {
void __iomem *rdbase;