RE: [PATCH 4/4] PCI: hv: Use the correct hypercall for unmasking interrupts on nested

Michael Kelley
2025-06-12T02:32:25Z

From: Nuno Das Neves <nunodasneves@linux.microsoft.com> Sent: Tuesday, June 10, 2025 4:52 PM
>
> 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, we should 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>
> ---
> 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..0f491c802fb9 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_nested && hv_root_partition())

Based on Patch 1 of this series, this driver is not loaded for the root
partition in the non-nested case. So testing hv_nested is redundant.

> + /*
> + * 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