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From: | Paolo Bonzini |
Subject: | Re: [PATCH 4/4] virtio-mmio: cleanup reset |
Date: | Thu, 9 Jun 2022 16:44:06 +0200 |
User-agent: | Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.9.0 |
On 6/9/22 14:22, Cornelia Huck wrote:
- if (proxy->legacy) { - return; - } + virtio_bus_reset(&proxy->bus);- for (i = 0; i < VIRTIO_QUEUE_MAX; i++) {- proxy->vqs[i].enabled = 0; + if (!proxy->legacy) { + for (i = 0; i < VIRTIO_QUEUE_MAX; i++) { + proxy->vqs[i].enabled = 0; + } } }The more I look at this, the more confused I get. The current code calls soft_reset when the driver sets the status to 0, after already having called virtio_reset().
Yes, that's before the patch.
No, it does not set enabled = 0 because "enabled" is specific to virtio-mmio (it is read by VIRTIO_MMIO_QUEUE_READY, which is only available in virtio-mmio 1.0 devices). In fact it is stored in proxy->vqs[], while virtio_reset only resets fields in vdev->vq[].But doesn't virtio_reset() ultimately already trigger the virtio-mmio reset routine, which sets enabled to 0 for all queues? Why do that again? (And why is soft_reset a "soft reset"?)
k->reset() instead triggers the *device* reset routine (e.g. virtio_blk_reset). So what makes it "soft" is that the various queue addresses remain there, and can be enabled just by writing 1 to VIRTIO_MMIO_QUEUE_READY for every queue.
Paolo
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