Re: [Qemu-devel] [PATCH 1/3] ivshmem: Don't update non-existent MSI routes

["Marc-André Lureau" <marcandre.lureau@redhat.com>]

----- Original Message -----
> As of commit 660c97eef6f8 ("ivshmem: use kvm irqfd for msi notifications"),
> QEMU crashes with:
> 
>   kvm_irqchip_commit_routes: Assertion `ret == 0' failed.
> 
> if the ivshmem device is configured with more vectors than what the server
> supports. This is caused by the ivshmem_vector_unmask() being called on
> vectors that have not been initialized by ivshmem_add_kvm_msi_virq().
> 
> This commit fixes it by adding a simple check to the mask and unmask
> callbacks.
> 
> Note that the opposite mismatch, if the server supplies more vectors than
> what the device is configured for, is already handled and leads to output
> like:
> 
>   Too many eventfd received, device has 1 vectors
> 
> Fixes: 660c97eef6f8 ("ivshmem: use kvm irqfd for msi notifications")
> Signed-off-by: Ladi Prosek <lprosek@redhat.com>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>

> ---
>  hw/misc/ivshmem.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/hw/misc/ivshmem.c b/hw/misc/ivshmem.c
> index a5a46827fe..6e46669744 100644
> --- a/hw/misc/ivshmem.c
> +++ b/hw/misc/ivshmem.c
> @@ -317,6 +317,10 @@ static int ivshmem_vector_unmask(PCIDevice *dev,
> unsigned vector,
>      int ret;
>  
>      IVSHMEM_DPRINTF("vector unmask %p %d\n", dev, vector);
> +    if (!v->pdev) {
> +        error_report("ivshmem: vector %d route does not exist", vector);
> +        return -EINVAL;
> +    }
>  
>      ret = kvm_irqchip_update_msi_route(kvm_state, v->virq, msg, dev);
>      if (ret < 0) {
> @@ -331,12 +335,16 @@ static void ivshmem_vector_mask(PCIDevice *dev,
> unsigned vector)
>  {
>      IVShmemState *s = IVSHMEM_COMMON(dev);
>      EventNotifier *n = &s->peers[s->vm_id].eventfds[vector];
> +    MSIVector *v = &s->msi_vectors[vector];
>      int ret;
>  
>      IVSHMEM_DPRINTF("vector mask %p %d\n", dev, vector);
> +    if (!v->pdev) {
> +        error_report("ivshmem: vector %d route does not exist", vector);
> +        return;
> +    }
>  
> -    ret = kvm_irqchip_remove_irqfd_notifier_gsi(kvm_state, n,
> -
> s->msi_vectors[vector].virq);
> +    ret = kvm_irqchip_remove_irqfd_notifier_gsi(kvm_state, n, v->virq);
>      if (ret != 0) {
>          error_report("remove_irqfd_notifier_gsi failed");
>      }
> --
> 2.13.5
> 
>