[PATCH v11 08/16] genirq/msi: Provide msi_device_domain_restore_msi_msgs()

[Pranjal Shrivastava <praan@google.com>]

From: Thomas Gleixner <tglx@kernel.org>

Devices that provide the message store for MSI interrupts in their own
hardware registers often lose that register state across power transitions
(such as runtime suspend or system sleep) and need to restore the cached
MSI messages upon resume.

Provide msi_device_domain_restore_msi_msgs() to iterate over all
associated MSI descriptors in a device's MSI domain under proper
descriptor and irq_desc locking and rewrite the cached MSI messages via
the irq_chip hierarchy.

Signed-off-by: Thomas Gleixner <tglx@kernel.org>
[praan: Use scoped_irqdesc_get_and_buslock(), fix the xarray range bound
 and write the commit message]
Signed-off-by: Pranjal Shrivastava <praan@google.com>
---
 include/linux/msi.h |  2 ++
 kernel/irq/msi.c    | 37 +++++++++++++++++++++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/include/linux/msi.h b/include/linux/msi.h
index a4613de11960..44d551e85abd 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -669,6 +669,8 @@ void msi_domain_free_irqs_all(struct device *dev, unsigned int domid);
 
 struct msi_domain_info *msi_get_domain_info(struct irq_domain *domain);
 
+void msi_device_domain_restore_msi_msgs(struct device *dev, unsigned int domid);
+
 /* Per device platform MSI */
 int platform_device_msi_init_and_alloc_irqs(struct device *dev, unsigned int nvec,
 					    irq_write_msi_msg_t write_msi_msg);
diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c
index df460a574d80..8fb855b5e09f 100644
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -1784,3 +1784,40 @@ bool msi_device_has_isolated_msi(struct device *dev)
 	return arch_is_isolated_msi();
 }
 EXPORT_SYMBOL_GPL(msi_device_has_isolated_msi);
+
+/**
+ * msi_device_domain_restore_msi_msgs - Restore MSI messages for a device domain
+ * @dev:	The device to restore MSI messages for
+ * @domid:	The id of the interrupt domain to restore
+ */
+void msi_device_domain_restore_msi_msgs(struct device *dev, unsigned int domid)
+{
+	if (!dev->msi.data)
+		return;
+
+	guard(msi_descs_lock)(dev);
+	struct irq_domain *domain = msi_get_device_domain(dev, domid);
+
+	if (!domain || !irq_domain_is_msi_device(domain))
+		return;
+
+	struct xarray *xa = &dev->msi.data->__domains[domid].store;
+	struct msi_domain_info *info = domain->host_data;
+	struct msi_desc *msi_desc;
+	unsigned long idx;
+
+	xa_for_each_range(xa, idx, msi_desc, 0, info->hwsize - 1) {
+		/* Only handle MSI entries which have an interrupt associated */
+		if (!msi_desc_match(msi_desc, MSI_DESC_ASSOCIATED))
+			continue;
+
+		scoped_irqdesc_get_and_buslock(msi_desc->irq, 0) {
+			struct irq_data *data = irq_desc_get_irq_data(scoped_irqdesc);
+			struct msi_msg msg = msi_desc->msg;
+
+			if (data->chip)
+				irq_chip_write_msi_msg(data, &msg);
+		}
+	}
+}
+EXPORT_SYMBOL_GPL(msi_device_domain_restore_msi_msgs);
-- 
2.56.0.rc1.315.gc6ed9934b7-goog