linux-kernel - [PATCH] irqchip/gic-v3-its: Handle non-coherent GICv4 redistributors

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Date: Sun, 14 Jan 2024 12:44:29 +0000
From: Marc Zyngier <maz@...nel.org>
To: linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org
Cc: Thomas Gleixner <tglx@...utronix.de>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>
Subject: [PATCH] irqchip/gic-v3-its: Handle non-coherent GICv4 redistributors

Although the GICv3 code base has gained some handling of systems
failing to handle the shareability attributes, the GICv4 side of
things has been firmly ignored.

This is unfortunate, as the new recent addition of the
"dma-noncoherent" is supposed to apply to all of the GICR tables,
and not just the ones that are common to v3 and v4.

Add some checks to handle the VPROPBASE/VPENDBASE shareability
and cacheability attributes in the same way we deal with the
other GICR_BASE registers, wrapping the flag check in a helper
for improved readability.

Note that this has been found by inspection only, as I don't
have access to HW that suffers from this particular issue.

Fixes: 3a0fff0fb6a3 ("irqchip/gic-v3: Enable non-coherent redistributors/ITSes DT probing")
Signed-off-by: Marc Zyngier <maz@...nel.org>
---
 drivers/irqchip/irq-gic-v3-its.c | 37 +++++++++++++++++++++-----------
 1 file changed, 25 insertions(+), 12 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
index 9a7a74239eab..bdc2c8330479 100644
--- a/drivers/irqchip/irq-gic-v3-its.c
+++ b/drivers/irqchip/irq-gic-v3-its.c
@@ -207,6 +207,11 @@ static bool require_its_list_vmovp(struct its_vm *vm, struct its_node *its)
 	return (gic_rdists->has_rvpeid || vm->vlpi_count[its->list_nr]);
 }
 
+static bool rdists_support_shareable(void)
+{
+	return !(gic_rdists->flags & RDIST_FLAGS_FORCE_NON_SHAREABLE);
+}
+
 static u16 get_its_list(struct its_vm *vm)
 {
 	struct its_node *its;
@@ -2710,10 +2715,12 @@ static u64 inherit_vpe_l1_table_from_its(void)
 			break;
 		}
 		val |= FIELD_PREP(GICR_VPROPBASER_4_1_ADDR, addr >> 12);
-		val |= FIELD_PREP(GICR_VPROPBASER_SHAREABILITY_MASK,
-				  FIELD_GET(GITS_BASER_SHAREABILITY_MASK, baser));
-		val |= FIELD_PREP(GICR_VPROPBASER_INNER_CACHEABILITY_MASK,
-				  FIELD_GET(GITS_BASER_INNER_CACHEABILITY_MASK, baser));
+		if (rdists_support_shareable()) {
+			val |= FIELD_PREP(GICR_VPROPBASER_SHAREABILITY_MASK,
+					  FIELD_GET(GITS_BASER_SHAREABILITY_MASK, baser));
+			val |= FIELD_PREP(GICR_VPROPBASER_INNER_CACHEABILITY_MASK,
+					  FIELD_GET(GITS_BASER_INNER_CACHEABILITY_MASK, baser));
+		}
 		val |= FIELD_PREP(GICR_VPROPBASER_4_1_SIZE, GITS_BASER_NR_PAGES(baser) - 1);
 
 		return val;
@@ -2936,8 +2943,10 @@ static int allocate_vpe_l1_table(void)
 	WARN_ON(!IS_ALIGNED(pa, psz));
 
 	val |= FIELD_PREP(GICR_VPROPBASER_4_1_ADDR, pa >> 12);
-	val |= GICR_VPROPBASER_RaWb;
-	val |= GICR_VPROPBASER_InnerShareable;
+	if (rdists_support_shareable()) {
+		val |= GICR_VPROPBASER_RaWb;
+		val |= GICR_VPROPBASER_InnerShareable;
+	}
 	val |= GICR_VPROPBASER_4_1_Z;
 	val |= GICR_VPROPBASER_4_1_VALID;
 
@@ -3126,7 +3135,7 @@ static void its_cpu_init_lpis(void)
 	gicr_write_propbaser(val, rbase + GICR_PROPBASER);
 	tmp = gicr_read_propbaser(rbase + GICR_PROPBASER);
 
-	if (gic_rdists->flags & RDIST_FLAGS_FORCE_NON_SHAREABLE)
+	if (!rdists_support_shareable())
 		tmp &= ~GICR_PROPBASER_SHAREABILITY_MASK;
 
 	if ((tmp ^ val) & GICR_PROPBASER_SHAREABILITY_MASK) {
@@ -3153,7 +3162,7 @@ static void its_cpu_init_lpis(void)
 	gicr_write_pendbaser(val, rbase + GICR_PENDBASER);
 	tmp = gicr_read_pendbaser(rbase + GICR_PENDBASER);
 
-	if (gic_rdists->flags & RDIST_FLAGS_FORCE_NON_SHAREABLE)
+	if (!rdists_support_shareable())
 		tmp &= ~GICR_PENDBASER_SHAREABILITY_MASK;
 
 	if (!(tmp & GICR_PENDBASER_SHAREABILITY_MASK)) {
@@ -3880,14 +3889,18 @@ static void its_vpe_schedule(struct its_vpe *vpe)
 	val  = virt_to_phys(page_address(vpe->its_vm->vprop_page)) &
 		GENMASK_ULL(51, 12);
 	val |= (LPI_NRBITS - 1) & GICR_VPROPBASER_IDBITS_MASK;
-	val |= GICR_VPROPBASER_RaWb;
-	val |= GICR_VPROPBASER_InnerShareable;
+	if (rdists_support_shareable()) {
+		val |= GICR_VPROPBASER_RaWb;
+		val |= GICR_VPROPBASER_InnerShareable;
+	}
 	gicr_write_vpropbaser(val, vlpi_base + GICR_VPROPBASER);
 
 	val  = virt_to_phys(page_address(vpe->vpt_page)) &
 		GENMASK_ULL(51, 16);
-	val |= GICR_VPENDBASER_RaWaWb;
-	val |= GICR_VPENDBASER_InnerShareable;
+	if (rdists_support_shareable()) {
+		val |= GICR_VPENDBASER_RaWaWb;
+		val |= GICR_VPENDBASER_InnerShareable;
+	}
 	/*
 	 * There is no good way of finding out if the pending table is
 	 * empty as we can race against the doorbell interrupt very
-- 
2.39.2