linux-kernel - [PATCH v3 2/3] x86/hyperv: Expose hv_map_msi

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Message-Id: <1752261532-7225-3-git-send-email-nunodasneves@linux.microsoft.com>
Date: Fri, 11 Jul 2025 12:18:51 -0700
From: Nuno Das Neves <nunodasneves@...ux.microsoft.com>
To: linux-hyperv@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	linux-pci@...r.kernel.org,
	wei.liu@...nel.org,
	mhklinux@...look.com,
	tglx@...utronix.de,
	bhelgaas@...gle.com,
	romank@...ux.microsoft.com
Cc: kys@...rosoft.com,
	haiyangz@...rosoft.com,
	decui@...rosoft.com,
	catalin.marinas@....com,
	will@...nel.org,
	mingo@...hat.com,
	bp@...en8.de,
	dave.hansen@...ux.intel.com,
	hpa@...or.com,
	lpieralisi@...nel.org,
	kw@...ux.com,
	robh@...nel.org,
	jinankjain@...ux.microsoft.com,
	skinsburskii@...ux.microsoft.com,
	mrathor@...ux.microsoft.com,
	x86@...nel.org,
	Nuno Das Neves <nunodasneves@...ux.microsoft.com>
Subject: [PATCH v3 2/3] x86/hyperv: Expose hv_map_msi_interrupt()

From: Stanislav Kinsburskii <skinsburskii@...ux.microsoft.com>

Move some of the logic of hv_irq_compose_irq_message() into
hv_map_msi_interrupt(). Make hv_map_msi_interrupt() a globally-available
helper function, which will be used to map PCI interrupts when running
in the root partition.

Signed-off-by: Stanislav Kinsburskii <skinsburskii@...ux.microsoft.com>
Signed-off-by: Nuno Das Neves <nunodasneves@...ux.microsoft.com>
Reviewed-by: Roman Kisel <romank@...ux.microsoft.com>
---
 arch/x86/hyperv/irqdomain.c     | 40 ++++++++++++++++++++++++---------
 arch/x86/include/asm/mshyperv.h |  2 ++
 2 files changed, 31 insertions(+), 11 deletions(-)

diff --git a/arch/x86/hyperv/irqdomain.c b/arch/x86/hyperv/irqdomain.c
index ad4dff48cf14..090f5ac9f492 100644
--- a/arch/x86/hyperv/irqdomain.c
+++ b/arch/x86/hyperv/irqdomain.c
@@ -173,13 +173,34 @@ static union hv_device_id hv_build_pci_dev_id(struct pci_dev *dev)
 	return dev_id;
 }
 
-static int hv_map_msi_interrupt(struct pci_dev *dev, int cpu, int vector,
-				struct hv_interrupt_entry *entry)
+/**
+ * hv_map_msi_interrupt() - "Map" the MSI IRQ in the hypervisor.
+ * @data:      Describes the IRQ
+ * @out_entry: Hypervisor (MSI) interrupt entry (can be NULL)
+ *
+ * Map the IRQ in the hypervisor by issuing a MAP_DEVICE_INTERRUPT hypercall.
+ *
+ * Return: 0 on success, -errno on failure
+ */
+int hv_map_msi_interrupt(struct irq_data *data,
+			 struct hv_interrupt_entry *out_entry)
 {
-	union hv_device_id device_id = hv_build_pci_dev_id(dev);
+	struct irq_cfg *cfg = irqd_cfg(data);
+	struct hv_interrupt_entry dummy;
+	union hv_device_id device_id;
+	struct msi_desc *msidesc;
+	struct pci_dev *dev;
+	int cpu;
 
-	return hv_map_interrupt(device_id, false, cpu, vector, entry);
+	msidesc = irq_data_get_msi_desc(data);
+	dev = msi_desc_to_pci_dev(msidesc);
+	device_id = hv_build_pci_dev_id(dev);
+	cpu = cpumask_first(irq_data_get_effective_affinity_mask(data));
+
+	return hv_map_interrupt(device_id, false, cpu, cfg->vector,
+				out_entry ? out_entry : &dummy);
 }
+EXPORT_SYMBOL_GPL(hv_map_msi_interrupt);
 
 static inline void entry_to_msi_msg(struct hv_interrupt_entry *entry, struct msi_msg *msg)
 {
@@ -192,11 +213,11 @@ static inline void entry_to_msi_msg(struct hv_interrupt_entry *entry, struct msi
 static int hv_unmap_msi_interrupt(struct pci_dev *dev, struct hv_interrupt_entry *old_entry);
 static void hv_irq_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
 {
-	struct hv_interrupt_entry out_entry, *stored_entry;
+	struct hv_interrupt_entry *stored_entry;
 	struct irq_cfg *cfg = irqd_cfg(data);
 	struct msi_desc *msidesc;
 	struct pci_dev *dev;
-	int cpu, ret;
+	int ret;
 
 	msidesc = irq_data_get_msi_desc(data);
 	dev = msi_desc_to_pci_dev(msidesc);
@@ -206,8 +227,6 @@ static void hv_irq_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
 		return;
 	}
 
-	cpu = cpumask_first(irq_data_get_effective_affinity_mask(data));
-
 	if (data->chip_data) {
 		/*
 		 * This interrupt is already mapped. Let's unmap first.
@@ -234,15 +253,14 @@ static void hv_irq_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
 		return;
 	}
 
-	ret = hv_map_msi_interrupt(dev, cpu, cfg->vector, &out_entry);
+	ret = hv_map_msi_interrupt(data, stored_entry);
 	if (ret) {
 		kfree(stored_entry);
 		return;
 	}
 
-	*stored_entry = out_entry;
 	data->chip_data = stored_entry;
-	entry_to_msi_msg(&out_entry, msg);
+	entry_to_msi_msg(data->chip_data, msg);
 
 	return;
 }
diff --git a/arch/x86/include/asm/mshyperv.h b/arch/x86/include/asm/mshyperv.h
index ab097a3a8b75..abc4659f5809 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -242,6 +242,8 @@ static inline void hv_apic_init(void) {}
 
 struct irq_domain *hv_create_pci_msi_domain(void);
 
+int hv_map_msi_interrupt(struct irq_data *data,
+			 struct hv_interrupt_entry *out_entry);
 int hv_map_ioapic_interrupt(int ioapic_id, bool level, int vcpu, int vector,
 		struct hv_interrupt_entry *entry);
 int hv_unmap_ioapic_interrupt(int ioapic_id, struct hv_interrupt_entry *entry);
-- 
2.34.1