linux-kernel - [PATCH 2/4] PCI/MSI: Add startup/shutdown support for per device MSI[X] domains

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Message-ID: <20250807112326.748740-3-inochiama@gmail.com>
Date: Thu,  7 Aug 2025 19:23:23 +0800
From: Inochi Amaoto <inochiama@...il.com>
To: Thomas Gleixner <tglx@...utronix.de>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Marc Zyngier <maz@...nel.org>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Inochi Amaoto <inochiama@...il.com>,
	Saurabh Sengar <ssengar@...ux.microsoft.com>,
	Shradha Gupta <shradhagupta@...ux.microsoft.com>,
	Jonathan Cameron <Jonathan.Cameron@...ei.com>,
	Nicolin Chen <nicolinc@...dia.com>,
	Jason Gunthorpe <jgg@...pe.ca>,
	Chen Wang <unicorn_wang@...look.com>
Cc: linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org,
	Yixun Lan <dlan@...too.org>,
	Longbin Li <looong.bin@...il.com>
Subject: [PATCH 2/4] PCI/MSI: Add startup/shutdown support for per device MSI[X] domains

As The RISC-V PLIC can not apply affinity setting without calling
irq_enable(), it will make the interrupt unavaible when using as
an underlying irq chip for MSI controller.

Introduce the irq_startup/irq_shutdown for PCI domain template with
new MSI domain flag. This allow the PLIC can be properly configurated
when calling irq_startup().

Suggested-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Inochi Amaoto <inochiama@...il.com>
---
 drivers/pci/msi/irqdomain.c | 52 +++++++++++++++++++++++++++++++++++++
 include/linux/msi.h         |  2 ++
 2 files changed, 54 insertions(+)

diff --git a/drivers/pci/msi/irqdomain.c b/drivers/pci/msi/irqdomain.c
index 0938ef7ebabf..f0d18cadbe20 100644
--- a/drivers/pci/msi/irqdomain.c
+++ b/drivers/pci/msi/irqdomain.c
@@ -148,6 +148,23 @@ static void pci_device_domain_set_desc(msi_alloc_info_t *arg, struct msi_desc *d
 	arg->hwirq = desc->msi_index;
 }
 
+static __always_inline void cond_shutdown_parent(struct irq_data *data)
+{
+	struct msi_domain_info *info = data->domain->host_data;
+
+	if (unlikely(info->flags & MSI_FLAG_PCI_MSI_STARTUP_PARENT))
+		irq_chip_shutdown_parent(data);
+}
+
+static __always_inline unsigned int cond_startup_parent(struct irq_data *data)
+{
+	struct msi_domain_info *info = data->domain->host_data;
+
+	if (unlikely(info->flags & MSI_FLAG_PCI_MSI_STARTUP_PARENT))
+		return irq_chip_startup_parent(data);
+	return 0;
+}
+
 static __always_inline void cond_mask_parent(struct irq_data *data)
 {
 	struct msi_domain_info *info = data->domain->host_data;
@@ -164,6 +181,23 @@ static __always_inline void cond_unmask_parent(struct irq_data *data)
 		irq_chip_unmask_parent(data);
 }
 
+static void pci_irq_shutdown_msi(struct irq_data *data)
+{
+	struct msi_desc *desc = irq_data_get_msi_desc(data);
+
+	pci_msi_mask(desc, BIT(data->irq - desc->irq));
+	cond_shutdown_parent(data);
+}
+
+static unsigned int pci_irq_startup_msi(struct irq_data *data)
+{
+	struct msi_desc *desc = irq_data_get_msi_desc(data);
+	unsigned int ret = cond_startup_parent(data);
+
+	pci_msi_unmask(desc, BIT(data->irq - desc->irq));
+	return ret;
+}
+
 static void pci_irq_mask_msi(struct irq_data *data)
 {
 	struct msi_desc *desc = irq_data_get_msi_desc(data);
@@ -194,6 +228,8 @@ static void pci_irq_unmask_msi(struct irq_data *data)
 static const struct msi_domain_template pci_msi_template = {
 	.chip = {
 		.name			= "PCI-MSI",
+		.irq_startup		= pci_irq_startup_msi,
+		.irq_shutdown		= pci_irq_shutdown_msi,
 		.irq_mask		= pci_irq_mask_msi,
 		.irq_unmask		= pci_irq_unmask_msi,
 		.irq_write_msi_msg	= pci_msi_domain_write_msg,
@@ -210,6 +246,20 @@ static const struct msi_domain_template pci_msi_template = {
 	},
 };
 
+static void pci_irq_shutdown_msix(struct irq_data *data)
+{
+	pci_msix_mask(irq_data_get_msi_desc(data));
+	cond_shutdown_parent(data);
+}
+
+static unsigned int pci_irq_startup_msix(struct irq_data *data)
+{
+	unsigned int ret = cond_startup_parent(data);
+
+	pci_msix_unmask(irq_data_get_msi_desc(data));
+	return ret;
+}
+
 static void pci_irq_mask_msix(struct irq_data *data)
 {
 	pci_msix_mask(irq_data_get_msi_desc(data));
@@ -234,6 +284,8 @@ EXPORT_SYMBOL_GPL(pci_msix_prepare_desc);
 static const struct msi_domain_template pci_msix_template = {
 	.chip = {
 		.name			= "PCI-MSIX",
+		.irq_startup		= pci_irq_startup_msix,
+		.irq_shutdown		= pci_irq_shutdown_msix,
 		.irq_mask		= pci_irq_mask_msix,
 		.irq_unmask		= pci_irq_unmask_msix,
 		.irq_write_msi_msg	= pci_msi_domain_write_msg,
diff --git a/include/linux/msi.h b/include/linux/msi.h
index e5e86a8529fb..3111ba95fbde 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -568,6 +568,8 @@ enum {
 	MSI_FLAG_PARENT_PM_DEV		= (1 << 8),
 	/* Support for parent mask/unmask */
 	MSI_FLAG_PCI_MSI_MASK_PARENT	= (1 << 9),
+	/* Support for parent startup/shutdown */
+	MSI_FLAG_PCI_MSI_STARTUP_PARENT	= (1 << 10),
 
 	/* Mask for the generic functionality */
 	MSI_GENERIC_FLAGS_MASK		= GENMASK(15, 0),
-- 
2.50.1