Re: [PATCH v2 09/21] hw/vfio/pci: Convert CONFIG_KVM check to runtime one

[Eric Auger <eric.auger@redhat.com>]

Hi Philippe,

On 3/9/25 12:09 AM, Philippe Mathieu-Daudé wrote:
> Use the runtime kvm_enabled() helper to check whether
> KVM is available or not.

Miss the "why" of this patch.

By the way I fail to remember/see where kvm_allowed is set.

I am also confused because we still have some code, like in
vfio/common.c which does both checks:
#ifdef CONFIG_KVM
        if (kvm_enabled()) {
            max_memslots = kvm_get_max_memslots();
        }
#endif


Thanks

Eric

>
> Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
> Reviewed-by: Pierrick Bouvier <pierrick.bouvier@linaro.org>
> Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
> Reviewed-by: Cédric Le Goater <clg@redhat.com>
> ---
>  hw/vfio/pci.c | 19 +++++++++----------
>  1 file changed, 9 insertions(+), 10 deletions(-)
>
> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> index fdbc15885d4..9872884ff8a 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -118,8 +118,13 @@ static void vfio_intx_eoi(VFIODevice *vbasedev)
>  
>  static bool vfio_intx_enable_kvm(VFIOPCIDevice *vdev, Error **errp)
>  {
> -#ifdef CONFIG_KVM
> -    int irq_fd = event_notifier_get_fd(&vdev->intx.interrupt);
> +    int irq_fd;
> +
> +    if (!kvm_enabled()) {
> +        return true;
> +    }
> +
> +    irq_fd = event_notifier_get_fd(&vdev->intx.interrupt);
>  
>      if (vdev->no_kvm_intx || !kvm_irqfds_enabled() ||
>          vdev->intx.route.mode != PCI_INTX_ENABLED ||
> @@ -171,16 +176,13 @@ fail_irqfd:
>  fail:
>      qemu_set_fd_handler(irq_fd, vfio_intx_interrupt, NULL, vdev);
>      vfio_unmask_single_irqindex(&vdev->vbasedev, VFIO_PCI_INTX_IRQ_INDEX);
> +
>      return false;
> -#else
> -    return true;
> -#endif
>  }
>  
>  static void vfio_intx_disable_kvm(VFIOPCIDevice *vdev)
>  {
> -#ifdef CONFIG_KVM
> -    if (!vdev->intx.kvm_accel) {
> +    if (!kvm_enabled() || !vdev->intx.kvm_accel) {
>          return;
>      }
>  
> @@ -211,7 +213,6 @@ static void vfio_intx_disable_kvm(VFIOPCIDevice *vdev)
>      vfio_unmask_single_irqindex(&vdev->vbasedev, VFIO_PCI_INTX_IRQ_INDEX);
>  
>      trace_vfio_intx_disable_kvm(vdev->vbasedev.name);
> -#endif
>  }
>  
>  static void vfio_intx_update(VFIOPCIDevice *vdev, PCIINTxRoute *route)
> @@ -278,7 +279,6 @@ static bool vfio_intx_enable(VFIOPCIDevice *vdev, Error **errp)
>      vdev->intx.pin = pin - 1; /* Pin A (1) -> irq[0] */
>      pci_config_set_interrupt_pin(vdev->pdev.config, pin);
>  
> -#ifdef CONFIG_KVM
>      /*
>       * Only conditional to avoid generating error messages on platforms
>       * where we won't actually use the result anyway.
> @@ -287,7 +287,6 @@ static bool vfio_intx_enable(VFIOPCIDevice *vdev, Error **errp)
>          vdev->intx.route = pci_device_route_intx_to_irq(&vdev->pdev,
>                                                          vdev->intx.pin);
>      }
> -#endif
>  
>      ret = event_notifier_init(&vdev->intx.interrupt, 0);
>      if (ret) {