[PATCH v2 5/6] x86: hyperv: Expose hv_map_msi_interrupt function

[Michael Kelley]

From: Nuno Das Neves <nunodasneves at linux.microsoft.com> Sent: Thursday, July 3, 2025 3:45 PM
> 
> From: Stanislav Kinsburskii <skinsburskii at 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.

Commit message still has "this patch". See suggested wording
in my comment on v1 of this patch.

> 
> Signed-off-by: Stanislav Kinsburskii <skinsburskii at linux.microsoft.com>
> Signed-off-by: Nuno Das Neves <nunodasneves at linux.microsoft.com>
> Reviewed-by: Roman Kisel <romank at linux.microsoft.com>
> ---
>  arch/x86/hyperv/irqdomain.c     | 38 +++++++++++++++++++++++----------
>  arch/x86/include/asm/mshyperv.h |  2 ++
>  2 files changed, 29 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/x86/hyperv/irqdomain.c b/arch/x86/hyperv/irqdomain.c
> index 75b25724b045..eca015563420 100644
> --- a/arch/x86/hyperv/irqdomain.c
> +++ b/arch/x86/hyperv/irqdomain.c
> @@ -172,13 +172,32 @@ 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)

Also document the return value?  At least to say that success returns 0,
while a failure returns a negative errno.

> + *
> + * 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 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)
>  {
> @@ -191,11 +210,11 @@ 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);
> @@ -205,8 +224,6 @@ 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.
> @@ -233,15 +250,14 @@ 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 e00a8431ef8e..42ea9c68f8c8 100644
> --- a/arch/x86/include/asm/mshyperv.h
> +++ b/arch/x86/include/asm/mshyperv.h
> @@ -241,6 +241,8 @@ 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