On Mon, May 11, 2026 at 07:12:42PM -0700, Mukesh R wrote:
> Ask the hypervisor to retarget interrupts to new guest cpu or vector
> upon guest irq migration. This happens in the irqfd update path.
>
Reviewed-by: Souradeep Chakrabarti <[email protected]>
> Signed-off-by: Mukesh R <[email protected]>
> ---
> drivers/hv/mshv_eventfd.c | 78 ++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 76 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/hv/mshv_eventfd.c b/drivers/hv/mshv_eventfd.c
> index 1f5c1e9ee9b7..c05201d857fd 100644
> --- a/drivers/hv/mshv_eventfd.c
> +++ b/drivers/hv/mshv_eventfd.c
> @@ -192,6 +192,77 @@ static int mshv_map_device_interrupt(u64 ptid, union
> hv_device_id hv_devid,
>
> }
>
> +/* NOTE: caller does spin_lock_irq on pt_irqfds_lock, hence no disable here
> */
> +static void mshv_do_guest_irq_retarget(u64 partid, struct mshv_irqfd *irqfd)
> +{
> + int rc, var_size;
> + u64 status;
> + union hv_device_id hv_devid;
> + struct hv_input_get_vp_set_from_mda *mda_input;
> + union hv_output_get_vp_set_from_mda *mda_output;
> + struct hv_retarget_device_interrupt *remap_inp;
> + struct pci_dev *pdev;
> + struct irq_data *irqdata;
> + struct mshv_lapic_irq *lapic_irq = &irqfd->irqfd_lapic_irq;
> + struct hv_interrupt_entry *inte = NULL;
> +
> + if (!irqfd->irqfd_girq_ent.girq_entry_valid ||
> + irqfd->irqfd_bypass_prod == NULL)
> + return;
> +
> + rc = mshv_parse_mshv_irqfd(irqfd, &pdev, &irqdata);
> + if (rc)
> + return;
> +
> + inte = irqdata->chip_data;
> + if (inte == NULL)
> + return;
> +
> + hv_devid.as_uint64 = hv_devid_from_pdev(pdev);
> +
> +
> + mda_input = *this_cpu_ptr(hyperv_pcpu_input_arg);
> + mda_output = *this_cpu_ptr(hyperv_pcpu_output_arg);
> +
> + rc = hv_vpset_from_hyp_disabled(mda_input, mda_output, lapic_irq,
> + partid);
> + if (rc)
> + return;
> +
> + remap_inp = *this_cpu_ptr(hyperv_pcpu_input_arg);
> + memset(remap_inp, 0, sizeof(*remap_inp));
> +
> + rc = hv_copy_vpset(&remap_inp->int_target.vp_set,
> + &mda_output->target_vpset);
> + if (rc <= 0) {
> + pr_err("Hyper-V: ptid %lld - vpset copy failed (%d)\n",
> + partid, rc);
> + return;
> + }
> +
> + /*
> + * var-sized hcall: var-size starts after vp_mask (thus vp_set.format
> + * does not count, but vp_set.valid_bank_mask does).
> + */
> + var_size = rc + 1;
> +
> + remap_inp->partition_id = partid;
> + remap_inp->device_id = hv_devid.as_uint64;
> + remap_inp->int_target.vector = lapic_irq->lapic_vector;
> + remap_inp->int_target.flags = HV_DEVICE_INTERRUPT_TARGET_PROCESSOR_SET;
> +
> + remap_inp->int_entry.source = inte->source;
> + remap_inp->int_entry.msi_entry.as_uint64 = inte->msi_entry.as_uint64;
> +
> + status = hv_do_rep_hypercall(HVCALL_RETARGET_INTERRUPT, 0, var_size,
> + remap_inp, NULL);
> +
> + if (!hv_result_success(status))
> + hv_status_err(status, "pt:%lld vec:%d lapic-id:%lld\n",
> + partid, lapic_irq->lapic_vector,
> + lapic_irq->lapic_apic_id);
> +}
> +
> static int mshv_unmap_device_interrupt(union hv_device_id hv_devid,
> struct hv_interrupt_entry *irq_entry)
> {
> @@ -729,9 +800,12 @@ static void mshv_irqfd_update(struct mshv_partition *pt,
> struct mshv_irqfd *irqfd)
> {
> write_seqcount_begin(&irqfd->irqfd_irqe_sc);
> - irqfd->irqfd_girq_ent = mshv_ret_girq_entry(pt,
> - irqfd->irqfd_irqnum);
> + irqfd->irqfd_girq_ent = mshv_ret_girq_entry(pt, irqfd->irqfd_irqnum);
> mshv_copy_girq_info(&irqfd->irqfd_girq_ent, &irqfd->irqfd_lapic_irq);
> +
> +#if IS_ENABLED(CONFIG_X86_64)
> + mshv_do_guest_irq_retarget(pt->pt_id, irqfd);
> +#endif
> write_seqcount_end(&irqfd->irqfd_irqe_sc);
> }
>
> --
> 2.51.2.vfs.0.1
>
