irqchip/gic-v3: Detect GICv4.1 supporting RVPEID

GICv4.1 supports the RVPEID ("Residency per vPE ID"), which allows for
a much efficient way of making virtual CPUs resident (to allow direct
injection of interrupts).

The functionnality needs to be discovered on each and every redistributor
in the system, and disabled if the settings are inconsistent.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Zenghui Yu <yuzenghui@huawei.com>
Link: https://lore.kernel.org/r/20191224111055.11836-2-maz@kernel.org

drivers/irqchip/irq-gic-v3.c

@@ -858,8 +858,21 @@ static int __gic_update_rdist_properties(struct redist_region *region,
 					 void __iomem *ptr)
 {
 	u64 typer = gic_read_typer(ptr + GICR_TYPER);
+
 	gic_data.rdists.has_vlpis &= !!(typer & GICR_TYPER_VLPIS);
-	gic_data.rdists.has_direct_lpi &= !!(typer & GICR_TYPER_DirectLPIS);
+
+	/* 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) |
+					   gic_data.rdists.has_rvpeid);
+
+	/* Detect non-sensical configurations */
+	if (WARN_ON_ONCE(gic_data.rdists.has_rvpeid && !gic_data.rdists.has_vlpis)) {
+		gic_data.rdists.has_direct_lpi = false;
+		gic_data.rdists.has_vlpis = false;
+		gic_data.rdists.has_rvpeid = false;
+	}
+
 	gic_data.ppi_nr = min(GICR_TYPER_NR_PPIS(typer), gic_data.ppi_nr);
 
 	return 1;
@@ -872,9 +885,10 @@ static void gic_update_rdist_properties(void)
 	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("%sVLPI support, %sdirect LPI support\n",
+	pr_info("%sVLPI support, %sdirect LPI support, %sRVPEID support\n",
 		!gic_data.rdists.has_vlpis ? "no " : "",
-		!gic_data.rdists.has_direct_lpi ? "no " : "");
+		!gic_data.rdists.has_direct_lpi ? "no " : "",
+		!gic_data.rdists.has_rvpeid ? "no " : "");
 }
 
 /* Check whether it's single security state view */
@@ -1566,6 +1580,7 @@ static int __init gic_init_bases(void __iomem *dist_base,
 						 &gic_data);
 	irq_domain_update_bus_token(gic_data.domain, DOMAIN_BUS_WIRED);
 	gic_data.rdists.rdist = alloc_percpu(typeof(*gic_data.rdists.rdist));
+	gic_data.rdists.has_rvpeid = true;
 	gic_data.rdists.has_vlpis = true;
 	gic_data.rdists.has_direct_lpi = true;
 

include/linux/irqchip/arm-gic-v3.h

@@ -234,6 +234,7 @@
 #define GICR_TYPER_VLPIS		(1U << 1)
 #define GICR_TYPER_DirectLPIS		(1U << 3)
 #define GICR_TYPER_LAST			(1U << 4)
+#define GICR_TYPER_RVPEID		(1U << 7)
 
 #define GIC_V3_REDIST_SIZE		0x20000
 
@@ -615,6 +616,7 @@ struct rdists {
 	u64			flags;
 	u32			gicd_typer;
 	bool			has_vlpis;
+	bool			has_rvpeid;
 	bool			has_direct_lpi;
 };