irqdomain/msi: Allow to override msi_domain_alloc/free_irqs()

To support MSI irq domains which do not fit at all into the regular MSI
irqdomain scheme, like the XEN MSI interrupt management for PV/HVM/DOM0,
it's necessary to allow to override the alloc/free implementation.

This is a preperatory step to switch X86 away from arch_*_msi_irqs() and
store the irq domain pointer right in struct device.

No functional change for existing MSI irq domain users.

Aside of the evil XEN wrapper this is also useful for special MSI domains
which need to do extra alloc/free work before/after calling the generic
core function. Work like allocating/freeing MSI descriptors, MSI storage
space etc.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20200826112333.526797548@linutronix.de

1 files changed, 48 insertions, 22 deletions

diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c
index 616b9583cfbb..2c0c4d6d0f83 100644
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -229,11 +229,13 @@ static int msi_domain_ops_check(struct irq_domain *domain,
 }
 
 static struct msi_domain_ops msi_domain_ops_default = {
-	.get_hwirq	= msi_domain_ops_get_hwirq,
-	.msi_init	= msi_domain_ops_init,
-	.msi_check	= msi_domain_ops_check,
-	.msi_prepare	= msi_domain_ops_prepare,
-	.set_desc	= msi_domain_ops_set_desc,
+	.get_hwirq		= msi_domain_ops_get_hwirq,
+	.msi_init		= msi_domain_ops_init,
+	.msi_check		= msi_domain_ops_check,
+	.msi_prepare		= msi_domain_ops_prepare,
+	.set_desc		= msi_domain_ops_set_desc,
+	.domain_alloc_irqs	= __msi_domain_alloc_irqs,
+	.domain_free_irqs	= __msi_domain_free_irqs,
 };
 
 static void msi_domain_update_dom_ops(struct msi_domain_info *info)
@@ -245,6 +247,14 @@ static void msi_domain_update_dom_ops(struct msi_domain_info *info)
 		return;
 	}
 
+	if (ops->domain_alloc_irqs == NULL)
+		ops->domain_alloc_irqs = msi_domain_ops_default.domain_alloc_irqs;
+	if (ops->domain_free_irqs == NULL)
+		ops->domain_free_irqs = msi_domain_ops_default.domain_free_irqs;
+
+	if (!(info->flags & MSI_FLAG_USE_DEF_DOM_OPS))
+		return;
+
 	if (ops->get_hwirq == NULL)
 		ops->get_hwirq = msi_domain_ops_default.get_hwirq;
 	if (ops->msi_init == NULL)
@@ -278,8 +288,7 @@ struct irq_domain *msi_create_irq_domain(struct fwnode_handle *fwnode,
 {
 	struct irq_domain *domain;
 
-	if (info->flags & MSI_FLAG_USE_DEF_DOM_OPS)
-		msi_domain_update_dom_ops(info);
+	msi_domain_update_dom_ops(info);
 	if (info->flags & MSI_FLAG_USE_DEF_CHIP_OPS)
 		msi_domain_update_chip_ops(info);
 
@@ -386,17 +395,8 @@ static bool msi_check_reservation_mode(struct irq_domain *domain,
 	return desc->msi_attrib.is_msix || desc->msi_attrib.maskbit;
 }
 
-/**
- * msi_domain_alloc_irqs - Allocate interrupts from a MSI interrupt domain
- * @domain:	The domain to allocate from
- * @dev:	Pointer to device struct of the device for which the interrupts
- *		are allocated
- * @nvec:	The number of interrupts to allocate
- *
- * Returns 0 on success or an error code.
- */
-int msi_domain_alloc_irqs(struct irq_domain *domain, struct device *dev,
-			  int nvec)
+int __msi_domain_alloc_irqs(struct irq_domain *domain, struct device *dev,
+			    int nvec)
 {
 	struct msi_domain_info *info = domain->host_data;
 	struct msi_domain_ops *ops = info->ops;
@@ -490,12 +490,24 @@ cleanup:
 }
 
 /**
- * msi_domain_free_irqs - Free interrupts from a MSI interrupt @domain associated tp @dev
- * @domain:	The domain to managing the interrupts
+ * msi_domain_alloc_irqs - Allocate interrupts from a MSI interrupt domain
+ * @domain:	The domain to allocate from
  * @dev:	Pointer to device struct of the device for which the interrupts
- *		are free
+ *		are allocated
+ * @nvec:	The number of interrupts to allocate
+ *
+ * Returns 0 on success or an error code.
  */
-void msi_domain_free_irqs(struct irq_domain *domain, struct device *dev)
+int msi_domain_alloc_irqs(struct irq_domain *domain, struct device *dev,
+			  int nvec)
+{
+	struct msi_domain_info *info = domain->host_data;
+	struct msi_domain_ops *ops = info->ops;
+
+	return ops->domain_alloc_irqs(domain, dev, nvec);
+}
+
+void __msi_domain_free_irqs(struct irq_domain *domain, struct device *dev)
 {
 	struct msi_desc *desc;
 
@@ -513,6 +525,20 @@ void msi_domain_free_irqs(struct irq_domain *domain, struct device *dev)
 }
 
 /**
+ * __msi_domain_free_irqs - Free interrupts from a MSI interrupt @domain associated tp @dev
+ * @domain:	The domain to managing the interrupts
+ * @dev:	Pointer to device struct of the device for which the interrupts
+ *		are free
+ */
+void msi_domain_free_irqs(struct irq_domain *domain, struct device *dev)
+{
+	struct msi_domain_info *info = domain->host_data;
+	struct msi_domain_ops *ops = info->ops;
+
+	return ops->domain_free_irqs(domain, dev);
+}
+
+/**
  * msi_get_domain_info - Get the MSI interrupt domain info for @domain
  * @domain:	The interrupt domain to retrieve data from
  *