Re: [PATCH v2 6/6] PCI: hv: Use the correct hypercall for unmasking interrupts on nested

[Bjorn Helgaas <helgaas@kernel.org>]

On Thu, Jul 03, 2025 at 03:44:37PM -0700, Nuno Das Neves wrote:
> From: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com>
> 
> Running as nested root on MSHV imposes a different requirement
> for the pci-hyperv controller.
> 
> In this setup, the interrupt will first come to the L1 (nested) hypervisor,
> which will deliver it to the appropriate root CPU. Instead of issuing the
> RETARGET hypercall, issue the MAP_DEVICE_INTERRUPT hypercall to L1 to
> complete the setup.
> 
> Rename hv_arch_irq_unmask() to hv_irq_retarget_interrupt().
> 
> Co-developed-by: Jinank Jain <jinankjain@linux.microsoft.com>
> Signed-off-by: Jinank Jain <jinankjain@linux.microsoft.com>
> 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>

Acked-by: Bjorn Helgaas <bhelgaas@google.com>

> ---
>  drivers/pci/controller/pci-hyperv.c | 18 ++++++++++++++++--
>  1 file changed, 16 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
> index 4d25754dfe2f..9a8cba39ea6b 100644
> --- a/drivers/pci/controller/pci-hyperv.c
> +++ b/drivers/pci/controller/pci-hyperv.c
> @@ -600,7 +600,7 @@ static unsigned int hv_msi_get_int_vector(struct irq_data *data)
>  #define hv_msi_prepare		pci_msi_prepare
>  
>  /**
> - * hv_arch_irq_unmask() - "Unmask" the IRQ by setting its current
> + * hv_irq_retarget_interrupt() - "Unmask" the IRQ by setting its current
>   * affinity.
>   * @data:	Describes the IRQ
>   *
> @@ -609,7 +609,7 @@ static unsigned int hv_msi_get_int_vector(struct irq_data *data)
>   * is built out of this PCI bus's instance GUID and the function
>   * number of the device.
>   */
> -static void hv_arch_irq_unmask(struct irq_data *data)
> +static void hv_irq_retarget_interrupt(struct irq_data *data)
>  {
>  	struct msi_desc *msi_desc = irq_data_get_msi_desc(data);
>  	struct hv_retarget_device_interrupt *params;
> @@ -714,6 +714,20 @@ static void hv_arch_irq_unmask(struct irq_data *data)
>  		dev_err(&hbus->hdev->device,
>  			"%s() failed: %#llx", __func__, res);
>  }
> +
> +static void hv_arch_irq_unmask(struct irq_data *data)
> +{
> +	if (hv_root_partition())
> +		/*
> +		 * In case of the nested root partition, the nested hypervisor
> +		 * is taking care of interrupt remapping and thus the
> +		 * MAP_DEVICE_INTERRUPT hypercall is required instead of
> +		 * RETARGET_INTERRUPT.
> +		 */
> +		(void)hv_map_msi_interrupt(data, NULL);
> +	else
> +		hv_irq_retarget_interrupt(data);
> +}
>  #elif defined(CONFIG_ARM64)
>  /*
>   * SPI vectors to use for vPCI; arch SPIs range is [32, 1019], but leaving a bit
> -- 
> 2.34.1
>