Re: [PATCH 1/2] virtio-mmio: synchronize callbacks during device reset

[Michael S. Tsirkin]

On Tue, Aug 18, 2026 at 06:04:32AM +0200, Karl Mehltretter wrote:
> virtio_reset_device() promises that vq callbacks are not in progress
> once it returns, but vm_reset() only writes 0 to the status register.
> A callback that has already entered vring_interrupt() keeps running
> while the driver tears down the state it uses.
> 
> Wait for a status read to return 0, so the device has stopped raising
> interrupts, then synchronize_irq() as vp_reset() does with
> vp_synchronize_vectors().
> 
> Fixes: edfd52e63672 ("virtio: Add platform bus driver for memory mapped virtio device")
> Assisted-by: Claude:claude-fable-5
> Signed-off-by: Karl Mehltretter <kmehltretter@xxxxxxxxx>
> ---
>  drivers/virtio/virtio_mmio.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
> index 510b7c4efdff8..a2ca03dbe803d 100644
> --- a/drivers/virtio/virtio_mmio.c
> +++ b/drivers/virtio/virtio_mmio.c
> @@ -55,6 +55,7 @@
>  #define pr_fmt(fmt) "virtio-mmio: " fmt
>  
>  #include <linux/acpi.h>
> +#include <linux/delay.h>
>  #include <linux/dma-mapping.h>
>  #include <linux/highmem.h>
>  #include <linux/interrupt.h>
> @@ -254,6 +255,11 @@ static void vm_reset(struct virtio_device *vdev)
>  
>  	/* 0 status means a reset. */
>  	writel(0, vm_dev->base + VIRTIO_MMIO_STATUS);
> +
> +	/* Wait for reset completion before flushing callbacks. */
> +	while (vm_get_status(vdev))
> +		fsleep(1000);

this is only required for transport version 3.


> +	synchronize_irq(platform_get_irq(vm_dev->pdev, 0));
>  }
>  
>  
> -- 
> 2.53.0