[PATCH v6 12/18] irqdomain: Add irq domain MSI and MSI_REMAP flags

[eric.auger@redhat.com (Eric Auger)]

We introduce two new enum values for the irq domain flag:
- IRQ_DOMAIN_FLAG_MSI indicates the irq domain corresponds to
  an MSI domain
- IRQ_DOMAIN_FLAG_MSI_REMAP indicates the irq domain has MSI
  remapping capabilities.

Those values will be useful to check all MSI irq domains have
MSI remapping support when assessing the safety of IRQ assignment
to a guest.

irq_domain_hierarchical_is_msi_remap() allows to check if an
irq domain or any parent implements MSI remapping.

Signed-off-by: Eric Auger <eric.auger@redhat.com>

---

v6:
- add IRQ_DOMAIN_FLAG_MSI as suggested by Marc
- add irq_domain_is_msi, irq_domain_is_msi_remap and
  irq_domain_hierarchical_is_msi_remap
---
 include/linux/irqdomain.h | 35 +++++++++++++++++++++++++++++++++++
 kernel/irq/irqdomain.c    | 16 ++++++++++++++++
 2 files changed, 51 insertions(+)

diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h
index ffb8460..bc2f571 100644
--- a/include/linux/irqdomain.h
+++ b/include/linux/irqdomain.h
@@ -183,6 +183,12 @@ enum {
 	/* Irq domain is an IPI domain with single virq */
 	IRQ_DOMAIN_FLAG_IPI_SINGLE	= (1 << 3),
 
+	/* Irq domain implements MSIs */
+	IRQ_DOMAIN_FLAG_MSI		= (1 << 4),
+
+	/* Irq domain implements MSI remapping */
+	IRQ_DOMAIN_FLAG_MSI_REMAP	= (1 << 5),
+
 	/*
 	 * Flags starting from IRQ_DOMAIN_FLAG_NONCORE are reserved
 	 * for implementation specific purposes and ignored by the
@@ -446,6 +452,19 @@ static inline bool irq_domain_is_ipi_single(struct irq_domain *domain)
 {
 	return domain->flags & IRQ_DOMAIN_FLAG_IPI_SINGLE;
 }
+
+static inline bool irq_domain_is_msi(struct irq_domain *domain)
+{
+	return domain->flags & IRQ_DOMAIN_FLAG_MSI;
+}
+
+static inline bool irq_domain_is_msi_remap(struct irq_domain *domain)
+{
+	return domain->flags & IRQ_DOMAIN_FLAG_MSI_REMAP;
+}
+
+extern bool irq_domain_hierarchical_is_msi_remap(struct irq_domain *domain);
+
 #else	/* CONFIG_IRQ_DOMAIN_HIERARCHY */
 static inline void irq_domain_activate_irq(struct irq_data *data) { }
 static inline void irq_domain_deactivate_irq(struct irq_data *data) { }
@@ -477,6 +496,22 @@ static inline bool irq_domain_is_ipi_single(struct irq_domain *domain)
 {
 	return false;
 }
+
+static inline bool irq_domain_is_msi(struct irq_domain *domain)
+{
+	return false;
+}
+
+static inline bool irq_domain_is_msi_remap(struct irq_domain *domain)
+{
+	return false;
+}
+
+static inline bool
+irq_domain_hierarchical_is_msi_remap(struct irq_domain *domain)
+{
+	return false;
+}
 #endif	/* CONFIG_IRQ_DOMAIN_HIERARCHY */
 
 #else /* CONFIG_IRQ_DOMAIN */
diff --git a/kernel/irq/irqdomain.c b/kernel/irq/irqdomain.c
index 8c0a0ae..6a946c4 100644
--- a/kernel/irq/irqdomain.c
+++ b/kernel/irq/irqdomain.c
@@ -1392,6 +1392,22 @@ static void irq_domain_check_hierarchy(struct irq_domain *domain)
 	if (domain->ops->alloc)
 		domain->flags |= IRQ_DOMAIN_FLAG_HIERARCHY;
 }
+
+/**
+ * irq_domain_hierarchical_is_msi_remap - Check if @domain or any parent
+ * has MSI remapping support
+ * @domain: domain pointer
+ */
+bool irq_domain_hierarchical_is_msi_remap(struct irq_domain *domain)
+{
+	struct irq_domain *h = domain;
+
+	for (; h; h = h->parent) {
+		if (irq_domain_is_msi_remap(h))
+			return true;
+	}
+	return false;
+}
 #else	/* CONFIG_IRQ_DOMAIN_HIERARCHY */
 /**
  * irq_domain_get_irq_data - Get irq_data associated with @virq and @domain
-- 
1.9.1