[PATCH V1 5/7] KVM: GICv2: Add ACPI probing function

[Wei Huang <wei@xxxxxxxxxx>]

This patch implements ACPI probing for GICv2.

Signed-off-by: Wei Huang <wei@xxxxxxxxxx>
---
 virt/kvm/arm/vgic-v2.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)

diff --git a/virt/kvm/arm/vgic-v2.c b/virt/kvm/arm/vgic-v2.c
index b60e73a..7de2a1f 100644
--- a/virt/kvm/arm/vgic-v2.c
+++ b/virt/kvm/arm/vgic-v2.c
@@ -23,6 +23,7 @@
 #include <linux/of.h>
 #include <linux/of_address.h>
 #include <linux/of_irq.h>
+#include <linux/acpi.h>
 
 #include <linux/irqchip/arm-gic.h>
 
@@ -226,6 +227,71 @@ out:
 	return ret;
 }
 
+#ifdef CONFIG_ACPI
+static struct acpi_madt_generic_interrupt *vgic_acpi;
+static void gic_get_acpi_header(struct acpi_subtable_header *header)
+{
+	vgic_acpi = (struct acpi_madt_generic_interrupt *)header;
+}
+
+static struct acpi_madt_generic_distributor *dist_acpi;
+static void gic_get_dist_header(struct acpi_subtable_header *header)
+{
+	dist_acpi = (struct acpi_madt_generic_distributor *)header;
+}
+
+static int vgic_v2_acpi_probe(struct vgic_params *vgic)
+{
+	int irq_mode, ret = 0;
+
+	ret = acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_INTERRUPT,
+			(acpi_tbl_entry_handler)gic_get_acpi_header, 0);
+	if (!ret) {
+		ret = -ENODEV;
+		goto out;
+	}
+
+	ret = acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_DISTRIBUTOR,
+			(acpi_tbl_entry_handler)gic_get_dist_header, 0);
+	if (!ret) {
+		kvm_err("Cannot get distributor entry from ACPI\n");
+		ret = -ENODEV;
+		goto out;
+	}
+
+	if (dist_acpi->version >= ACPI_MADT_GIC_VERSION_V3) {
+		ret = -ENODEV;
+		goto out;
+	}
+
+	irq_mode = (vgic_acpi->flags & ACPI_MADT_VGIC_IRQ_MODE) ?
+		ACPI_EDGE_SENSITIVE : ACPI_LEVEL_SENSITIVE;
+	/* According to GIC-400 manual, PPIs are active-LOW, level-sensative.
+	 * We register IRQ as active-low.
+	 */
+	vgic->maint_irq = acpi_register_gsi(NULL, vgic_acpi->vgic_interrupt,
+					    irq_mode, ACPI_ACTIVE_LOW);
+	if (!vgic->maint_irq) {
+		kvm_err("Cannot register vgic maintenance irq from ACPI\n");
+		ret = -ENXIO;
+		goto out;
+	}
+
+	vgic->vctrl_phys_base = vgic_acpi->gich_base_address;
+	vgic->vctrl_size = SZ_8K;
+
+	vgic->vcpu_phys_base = vgic_acpi->gicv_base_address;
+	vgic->vcpu_size = 0; /* unavailable in ACPI, set to 0 */
+out:
+	return ret;
+}
+#else
+static inline int vgic_v2_acpi_probe(struct vgic_params *vgic)
+{
+	return -ENODEV;
+}
+#endif /* CONFIG_ACPI */
+
 /**
  * vgic_v2_probe - probe for a GICv2 compatible interrupt controller
  * @ops:	address of a pointer to the GICv2 operations
@@ -242,6 +308,8 @@ int vgic_v2_probe(const struct vgic_ops **ops,
 	struct vgic_params *vgic = &vgic_v2_params;
 
 	ret = vgic_v2_dt_probe(vgic);
+	if (ret && !acpi_disabled)
+		ret = vgic_v2_acpi_probe(vgic);
 	if (ret)
 		goto err_out;
 
-- 
1.8.3.1

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