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Re: [Qemu-devel] [PATCH 2/2] virtio-rng: stop virtqueue while the CPU is
From: |
Stefan Hajnoczi |
Subject: |
Re: [Qemu-devel] [PATCH 2/2] virtio-rng: stop virtqueue while the CPU is stopped |
Date: |
Tue, 11 Apr 2017 18:02:50 +0100 |
User-agent: |
Mutt/1.8.0 (2017-02-23) |
On Tue, Apr 11, 2017 at 03:17:33PM +0200, Laurent Vivier wrote:
> diff --git a/hw/virtio/virtio-rng.c b/hw/virtio/virtio-rng.c
> index 9639f4e..d270d56 100644
> --- a/hw/virtio/virtio-rng.c
> +++ b/hw/virtio/virtio-rng.c
> @@ -53,6 +53,15 @@ static void chr_read(void *opaque, const void *buf, size_t
> size)
> return;
> }
>
> + /* we can't modify the virtqueue until
> + * our state is fully synced
> + */
> +
> + if (!runstate_check(RUN_STATE_RUNNING)) {
> + trace_virtio_rng_cpu_is_stopped(vrng);
> + return;
> + }
> +
I'm concerned about what happens when the guest is stopped and resumed
(e.g. 'stop' and 'cont' monitor commands). Since we throw away the
chr_read() callback the device will hang unless the guest kicks it
again?
It's not clear to me that the rate limit timer will help us...
Stefan
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