[PATCH 3/4] x86: hyperv: Expose hv_map_msi_interrupt function

Nuno Das Neves
2025-06-10T23:52:09Z

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

This patch moves a part of currently internal logic into the
hv_map_msi_interrupt function and makes it globally available helper
function, which will be used to map PCI interrupts in case of root
partition.

Signed-off-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
---
arch/x86/hyperv/irqdomain.c | 47 ++++++++++++++++++++++++---------
arch/x86/include/asm/mshyperv.h | 2 ++
2 files changed, 36 insertions(+), 13 deletions(-)

diff --git a/arch/x86/hyperv/irqdomain.c b/arch/x86/hyperv/irqdomain.c
index 31f0d29cbc5e..82f3bafb93d6 100644
--- a/arch/x86/hyperv/irqdomain.c
+++ b/arch/x86/hyperv/irqdomain.c
@@ -169,13 +169,40 @@ 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.
+ */
+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 msi_desc *msidesc;
+ struct pci_dev *dev;
+ union hv_device_id device_id;
+ struct hv_interrupt_entry dummy;
+ struct irq_cfg *cfg = irqd_cfg(data);
+ const cpumask_t *affinity;
+ int cpu;
+ u64 res;

- 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);
+ affinity = irq_data_get_effective_affinity_mask(data);
+ cpu = cpumask_first_and(affinity, cpu_online_mask);
+
+ res = hv_map_interrupt(device_id, false, cpu, cfg->vector,
+ out_entry ? out_entry : &dummy);
+ if (!hv_result_success(res))
+ pr_err("%s: failed to map interrupt: %s",
+ __func__, hv_result_to_string(res));
+
+ return hv_result_to_errno(res);
}
+EXPORT_SYMBOL_GPL(hv_map_msi_interrupt);

static inline void entry_to_msi_msg(struct hv_interrupt_entry *entry, struct msi_msg *msg)
{
@@ -190,10 +217,8 @@ static void hv_irq_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
{
struct msi_desc *msidesc;
struct pci_dev *dev;
- struct hv_interrupt_entry out_entry, *stored_entry;
+ struct hv_interrupt_entry *stored_entry;
struct irq_cfg *cfg = irqd_cfg(data);
- const cpumask_t *affinity;
- int cpu;
u64 status;

msidesc = irq_data_get_msi_desc(data);
@@ -204,9 +229,6 @@ static void hv_irq_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
return;
}

- affinity = irq_data_get_effective_affinity_mask(data);
- cpu = cpumask_first_and(affinity, cpu_online_mask);
-
if (data->chip_data) {
/*
* This interrupt is already mapped. Let's unmap first.
@@ -235,15 +257,14 @@ static void hv_irq_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
return;
}

- status = hv_map_msi_interrupt(dev, cpu, cfg->vector, &out_entry);
+ status = hv_map_msi_interrupt(data, stored_entry);
if (status != HV_STATUS_SUCCESS) {
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 5ec92e3e2e37..843121465ddd 100644
--- a/arch/x86/include/asm/mshyperv.h
+++ b/arch/x86/include/asm/mshyperv.h
@@ -261,6 +261,8 @@ 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