linux-kernel - [patch 06/32] genirq/msi: Provide domain flags to allocate/free MSI descriptors automatically

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Date:   Sat, 27 Nov 2021 02:23:38 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Bjorn Helgaas <helgaas@...nel.org>, Marc Zygnier <maz@...nel.org>,
        Alex Williamson <alex.williamson@...hat.com>,
        Kevin Tian <kevin.tian@...el.com>,
        Jason Gunthorpe <jgg@...dia.com>,
        Megha Dey <megha.dey@...el.com>,
        Ashok Raj <ashok.raj@...el.com>, linux-pci@...r.kernel.org,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-s390@...r.kernel.org, Heiko Carstens <hca@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ibm.com>,
        Jon Mason <jdmason@...zu.us>,
        Dave Jiang <dave.jiang@...el.com>,
        Allen Hubbe <allenbh@...il.com>, linux-ntb@...glegroups.com
Subject: [patch 06/32] genirq/msi: Provide domain flags to allocate/free MSI
 descriptors automatically

Provide domain info flags which tell the core to allocate simple
descriptors or to free descriptors when the interrupts are freed and
implement the required functionality.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
 include/linux/msi.h |   15 +++++++++++++++
 kernel/irq/msi.c    |   48 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 63 insertions(+)

--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -303,6 +303,17 @@ static inline void pci_write_msi_msg(uns
 #endif /* CONFIG_PCI_MSI */
 
 int msi_add_msi_desc(struct device *dev, struct msi_desc *init_desc);
+void msi_free_msi_descs_range(struct device *dev, enum msi_desc_filter filter,
+			      unsigned int base_index, unsigned int ndesc);
+
+/**
+ * msi_free_msi_descs - Free MSI descriptors of a device
+ * @dev:	Device to free the descriptors
+ */
+static inline void msi_free_msi_descs(struct device *dev)
+{
+	msi_free_msi_descs_range(dev, MSI_DESC_ALL, 0, UINT_MAX);
+}
 
 struct msi_desc *alloc_msi_entry(struct device *dev, int nvec,
 				 const struct irq_affinity_desc *affinity);
@@ -463,6 +474,10 @@ enum {
 	MSI_FLAG_DEV_SYSFS		= (1 << 7),
 	/* MSI-X entries must be contiguous */
 	MSI_FLAG_MSIX_CONTIGUOUS	= (1 << 8),
+	/* Allocate simple MSI descriptors */
+	MSI_FLAG_ALLOC_SIMPLE_MSI_DESCS	= (1 << 9),
+	/* Free MSI descriptors */
+	MSI_FLAG_FREE_MSI_DESCS		= (1 << 10),
 };
 
 int msi_domain_set_affinity(struct irq_data *data, const struct cpumask *mask,
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -120,6 +120,32 @@ static int msi_add_simple_msi_descs(stru
 }
 
 /**
+ * msi_free_msi_descs_range - Free MSI descriptors of a device
+ * @dev:	Device to free the descriptors
+ * @filter:	Descriptor state filter
+ * @base_index:	Index to start freeing from
+ * @ndesc:	Number of descriptors to free
+ */
+void msi_free_msi_descs_range(struct device *dev, enum msi_desc_filter filter,
+			      unsigned int base_index, unsigned int ndesc)
+{
+	struct msi_desc *desc;
+
+	lockdep_assert_held(&dev->msi.data->mutex);
+
+	msi_for_each_desc(desc, dev, filter) {
+		/*
+		 * Stupid for now to handle MSI device domain until the
+		 * storage is switched over to an xarray.
+		 */
+		if (desc->msi_index < base_index || desc->msi_index >= base_index + ndesc)
+			continue;
+		list_del(&desc->list);
+		free_msi_entry(desc);
+	}
+}
+
+/**
  * msi_device_has_property - Check whether a device has a specific MSI property
  * @dev:	Pointer to the device which is queried
  * @prop:	Property to check for
@@ -905,6 +931,16 @@ int __msi_domain_alloc_irqs(struct irq_d
 	return 0;
 }
 
+static int msi_domain_add_simple_msi_descs(struct msi_domain_info *info,
+					   struct device *dev,
+					   unsigned int num_descs)
+{
+	if (!(info->flags & MSI_FLAG_ALLOC_SIMPLE_MSI_DESCS))
+		return 0;
+
+	return msi_add_simple_msi_descs(dev, 0, num_descs);
+}
+
 /**
  * msi_domain_alloc_irqs_descs_locked - Allocate interrupts from a MSI interrupt domain
  * @domain:	The domain to allocate from
@@ -927,6 +963,10 @@ int msi_domain_alloc_irqs_descs_locked(s
 
 	lockdep_assert_held(&dev->msi.data->mutex);
 
+	ret = msi_domain_add_simple_msi_descs(info, dev, nvec);
+	if (ret)
+		return ret;
+
 	ret = ops->domain_alloc_irqs(domain, dev, nvec);
 	if (ret)
 		goto cleanup;
@@ -988,6 +1028,13 @@ void __msi_domain_free_irqs(struct irq_d
 	}
 }
 
+static void msi_domain_free_msi_descs(struct msi_domain_info *info,
+				      struct device *dev)
+{
+	if (info->flags & MSI_FLAG_FREE_MSI_DESCS)
+		msi_free_msi_descs(dev);
+}
+
 /**
  * msi_domain_free_irqs_descs_locked - Free interrupts from a MSI interrupt @domain associated to @dev
  * @domain:	The domain to managing the interrupts
@@ -1008,6 +1055,7 @@ void msi_domain_free_irqs_descs_locked(s
 	if (info->flags & MSI_FLAG_DEV_SYSFS)
 		msi_device_destroy_sysfs(dev);
 	ops->domain_free_irqs(domain, dev);
+	msi_domain_free_msi_descs(info, dev);
 }
 
 /**