linux-kernel - [PATCH 2/3] irqchip/gic-v3: Detect LPI invalidation MMIO registers

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Date:   Tue, 15 Mar 2022 16:50:33 +0000
From:   Marc Zyngier <maz@...nel.org>
To:     linux-kernel@...r.kernel.org
Cc:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Andre Przywara <andre.przywara@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Eric Auger <eric.auger@...hat.com>
Subject: [PATCH 2/3] irqchip/gic-v3: Detect LPI invalidation MMIO registers

Since GICv4.1, an implementation can offer the same MMIO-based
implementation as DirectLPI, only with an ITS. Given that this
can be hugely beneficial for workloads that are very LPI masking
heavy (although these workloads are admitedly a bit odd).

Interestingly, this is independent of RVPEI, which only *implies*
the functionnality.

So let's detect whether the implementation has GICR_CTLR.IR set,
and propagate this as DirectLPI to the ITS driver.

Signed-off-by: Marc Zyngier <maz@...nel.org>
---
 drivers/irqchip/irq-gic-v3.c       | 15 +++++++++++----
 include/linux/irqchip/arm-gic-v3.h |  2 ++
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index 736163d36b13..363bfe172033 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -918,7 +918,11 @@ static int gic_populate_rdist(void)
 static int __gic_update_rdist_properties(struct redist_region *region,
 					 void __iomem *ptr)
 {
-	u64 typer = gic_read_typer(ptr + GICR_TYPER);
+	u64 typer;
+	u32 ctlr;
+
+	typer = gic_read_typer(ptr + GICR_TYPER);
+	ctlr = readl_relaxed(ptr + GICR_CTLR);
 
 	/* Boot-time cleanip */
 	if ((typer & GICR_TYPER_VLPIS) && (typer & GICR_TYPER_RVPEID)) {
@@ -941,6 +945,7 @@ static int __gic_update_rdist_properties(struct redist_region *region,
 	/* RVPEID implies some form of DirectLPI, no matter what the doc says... :-/ */
 	gic_data.rdists.has_rvpeid &= !!(typer & GICR_TYPER_RVPEID);
 	gic_data.rdists.has_direct_lpi &= (!!(typer & GICR_TYPER_DirectLPIS) |
+					   !!(ctlr & GICR_CTLR_IR) |
 					   gic_data.rdists.has_rvpeid);
 	gic_data.rdists.has_vpend_valid_dirty &= !!(typer & GICR_TYPER_DIRTY);
 
@@ -962,7 +967,11 @@ static void gic_update_rdist_properties(void)
 	gic_iterate_rdists(__gic_update_rdist_properties);
 	if (WARN_ON(gic_data.ppi_nr == UINT_MAX))
 		gic_data.ppi_nr = 0;
-	pr_info("%d PPIs implemented\n", gic_data.ppi_nr);
+	pr_info("GICv3 features: %d PPIs, %s%s\n",
+		gic_data.ppi_nr,
+		gic_data.has_rss ? "RSS " : "",
+		gic_data.rdists.has_direct_lpi ? "DirectLPI " : "");
+	
 	if (gic_data.rdists.has_vlpis)
 		pr_info("GICv4 features: %s%s%s\n",
 			gic_data.rdists.has_direct_lpi ? "DirectLPI " : "",
@@ -1797,8 +1806,6 @@ static int __init gic_init_bases(void __iomem *dist_base,
 	irq_domain_update_bus_token(gic_data.domain, DOMAIN_BUS_WIRED);
 
 	gic_data.has_rss = !!(typer & GICD_TYPER_RSS);
-	pr_info("Distributor has %sRange Selector support\n",
-		gic_data.has_rss ? "" : "no ");
 
 	if (typer & GICD_TYPER_MBIS) {
 		err = mbi_init(handle, gic_data.domain);
diff --git a/include/linux/irqchip/arm-gic-v3.h b/include/linux/irqchip/arm-gic-v3.h
index 12d91f0dedf9..aeb8ced53880 100644
--- a/include/linux/irqchip/arm-gic-v3.h
+++ b/include/linux/irqchip/arm-gic-v3.h
@@ -127,6 +127,8 @@
 #define GICR_PIDR2			GICD_PIDR2
 
 #define GICR_CTLR_ENABLE_LPIS		(1UL << 0)
+#define GICR_CTLR_IR			(1UL << 1)
+#define GICR_CTLR_CES			(1UL << 2)
 #define GICR_CTLR_RWP			(1UL << 3)
 
 #define GICR_TYPER_CPU_NUMBER(r)	(((r) >> 8) & 0xffff)
-- 
2.34.1