[tip: irq/core] irqchip/gic-v4.1: Don't use the VPE proxy if RVPEID is set

tip-bot2 for Marc Zyngier
2020-01-24T19:13:04Z

The following commit has been merged into the irq/core branch of tip:

Commit-ID: 0684c7046590dd1e8047e187aaf4c7910cc35bce
Gitweb: https://git.kernel.org/tip/0684c7046590dd1e8047e187aaf4c7910cc35bce
Author: Marc Zyngier <maz@kernel.org>
AuthorDate: Tue, 24 Dec 2019 11:10:30
Committer: Marc Zyngier <maz@kernel.org>
CommitterDate: Wed, 22 Jan 2020 14:22:20

irqchip/gic-v4.1: Don't use the VPE proxy if RVPEID is set

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>
Reviewed-by: Zenghui Yu <yuzenghui@huawei.com>
Link: https://lore.kernel.org/r/20191224111055.11836-8-maz@kernel.org
---
drivers/irqchip/irq-gic-v3-its.c | 25 ++++++++++++++++++++++++-
1 file changed, 24 insertions(+), 1 deletion(-)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index fbf4ca7..9bc8adf 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -3212,7 +3212,7 @@ 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
@@ -3220,9 +3220,20 @@ 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, on the other hand, 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, as the redistributor can be told
+ * whether to generate a doorbell or not (we thus leave it enabled,
+ * always).
*/
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;
@@ -3245,6 +3256,10 @@ 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;

@@ -3256,6 +3271,10 @@ 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;
@@ -3278,6 +3297,10 @@ 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;