Re: [PATCH QEMU HCI-8.1 08/21] migration: ensure APIC is loaded prior to VFIO PCI devices

[no-reply@sashiko.virtuozzo.com]

> From: Yanfei Xu <yanfei.xu@bytedance.com>
> 
> The load procedure of VFIO PCI devices involves setting up IRT
> for each VFIO PCI devices. This requires determining whether an
> interrupt is single-destination interrupt to decide between
> Posted Interrupt(PI) or remapping mode for the IRTE. However,
> determining this may require accessing the VM's APIC registers.
> 
> For example:
> ioctl(vbasedev->fd, VFIO_DEVICE_SET_IRQS, irqs)
>   ...
>     kvm_arch_irq_bypass_add_producer
>       kvm_x86_call(pi_update_irte)
>         vmx_pi_update_irte
>           kvm_intr_is_single_vcpu
> 
> If the LAPIC has not been loaded yet, interrupts will use remapping
> mode. To prevent the fallback of interrupt mode, keep APIC is always
> loaded prior to VFIO PCI devices.
> 
> andrey.drobyshev:
>     This commit is cherry-picked as-is, with no modifications, from the
>     upstream commit d943cef76090.
> 
> Signed-off-by: Yicong Shen <shenyicong.1023@bytedance.com>
> Signed-off-by: Yanfei Xu <yanfei.xu@bytedance.com>
> Reviewed-by: Peter Xu <peterx@redhat.com>
> Link: https://lore.kernel.org/r/20250818131127.1021648-1-yanfei.xu@bytedance.com
> Signed-off-by: Peter Xu <peterx@redhat.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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Sashiko AI review · https://sashiko.vzint.dev/#/patchset/20261009-vfio_v1-v1-0-2ae91d5b8048@virtuozzo.com?part=8