When vfio_enable_vectors() returns with less than requested nr_vectors
we retry with what kernel reported back. But the retry path doesn't
call vfio_prepare_kvm_msi_virq_batch() and this results in,

qemu-system-aarch64: vfio: Error: Failed to enable 4 MSI vectors, retry with 1
qemu-system-aarch64: ../hw/vfio/pci.c:602: vfio_commit_kvm_msi_virq_batch: Assertion `vdev->defer_kvm_irq_routing' failed

Fixes: dc580d51f7dd ("vfio: defer to commit kvm irq routing when enable msi/msix")
Reviewed-by: Longpeng <longpeng2@huawei.com>
Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
---
 hw/vfio/pci.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
index 73874a94de..8fb2c53a63 100644
--- a/hw/vfio/pci.c
+++ b/hw/vfio/pci.c
@@ -663,6 +663,8 @@ static void vfio_msi_enable(VFIOPCIDevice *vdev)
 
     vfio_disable_interrupts(vdev);
 
+    vdev->nr_vectors = msi_nr_vectors_allocated(&vdev->pdev);
+retry:
     /*
      * Setting vector notifiers needs to enable route for each vector.
      * Deferring to commit the KVM routes once rather than per vector
@@ -670,8 +672,6 @@ static void vfio_msi_enable(VFIOPCIDevice *vdev)
      */
     vfio_prepare_kvm_msi_virq_batch(vdev);
 
-    vdev->nr_vectors = msi_nr_vectors_allocated(&vdev->pdev);
-retry:
     vdev->msi_vectors = g_new0(VFIOMSIVector, vdev->nr_vectors);
 
     for (i = 0; i < vdev->nr_vectors; i++) {
-- 
2.34.1

Hello Shameer,

On 6/13/23 16:09, Shameer Kolothum wrote:
> When vfio_enable_vectors() returns with less than requested nr_vectors
> we retry with what kernel reported back. But the retry path doesn't
> call vfio_prepare_kvm_msi_virq_batch() and this results in,
> 
> qemu-system-aarch64: vfio: Error: Failed to enable 4 MSI vectors, retry with 1
> qemu-system-aarch64: ../hw/vfio/pci.c:602: vfio_commit_kvm_msi_virq_batch: Assertion `vdev->defer_kvm_irq_routing' failed
> 
> Fixes: dc580d51f7dd ("vfio: defer to commit kvm irq routing when enable msi/msix")
> Reviewed-by: Longpeng <longpeng2@huawei.com>
> Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>

Looks correct to me,

Reviewed-by: Cédric Le Goater <clg@redhat.com>

Thanks,

C.

> ---
>   hw/vfio/pci.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/vfio/pci.c b/hw/vfio/pci.c
> index 73874a94de..8fb2c53a63 100644
> --- a/hw/vfio/pci.c
> +++ b/hw/vfio/pci.c
> @@ -663,6 +663,8 @@ static void vfio_msi_enable(VFIOPCIDevice *vdev)
>   
>       vfio_disable_interrupts(vdev);
>   
> +    vdev->nr_vectors = msi_nr_vectors_allocated(&vdev->pdev);
> +retry:
>       /*
>        * Setting vector notifiers needs to enable route for each vector.
>        * Deferring to commit the KVM routes once rather than per vector
> @@ -670,8 +672,6 @@ static void vfio_msi_enable(VFIOPCIDevice *vdev)
>        */
>       vfio_prepare_kvm_msi_virq_batch(vdev);
>   
> -    vdev->nr_vectors = msi_nr_vectors_allocated(&vdev->pdev);
> -retry:
>       vdev->msi_vectors = g_new0(VFIOMSIVector, vdev->nr_vectors);
>   
>       for (i = 0; i < vdev->nr_vectors; i++) {