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

[Nuno Das Neves <nunodasneves@linux.microsoft.com>]

On 7/6/2025 8:14 PM, Michael Kelley wrote:
> From: Nuno Das Neves <nunodasneves@linux.microsoft.com> Sent: Thursday, July 3, 2025 3:45 PM
>>
>> 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.
> 
> Commit message still has "this patch". See suggested wording
> in my comment on v1 of this patch.
> 
Ah, indeed, I missed the change somehow :(

>>
>> Signed-off-by: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
>> Signed-off-by: Nuno Das Neves <nunodasneves@linux.microsoft.com>
>> Reviewed-by: Roman Kisel <romank@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