Re: [Qemu-devel] [PATCH v4 2/9] util: Introduce vfio helpers

[Stefan Hajnoczi <stefanha@redhat.com>]

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On Wed, Jan 10, 2018 at 05:18:39PM +0800, Fam Zheng wrote:
> +/* Map [host, host + size) area into a contiguous IOVA address space, and store
> + * the result in @iova if not NULL. The caller need to make sure the area is
> + * aligned to page size, and mustn't overlap with existing mapping areas (split
> + * mapping status within this area is not allowed).
> + */
> +int qemu_vfio_dma_map(QEMUVFIOState *s, void *host, size_t size,
> +                      bool temporary, uint64_t *iova)
> +{
> +    int ret = 0;
> +    int index;
> +    IOVAMapping *mapping;
> +    uint64_t iova0;
> +
> +    assert(QEMU_PTR_IS_ALIGNED(host, getpagesize()));
> +    assert(QEMU_IS_ALIGNED(size, getpagesize()));
> +    trace_qemu_vfio_dma_map(s, host, size, temporary, iova);
> +    qemu_mutex_lock(&s->lock);
> +    mapping = qemu_vfio_find_mapping(s, host, &index);
> +    if (mapping) {
> +        iova0 = mapping->iova + ((uint8_t *)host - (uint8_t *)mapping->host);
> +    } else {
> +        if (s->high_water_mark - s->low_water_mark + 1 < size) {
> +            ret = -ENOMEM;
> +            goto out;
> +        }
> +        if (!temporary) {
> +            iova0 = s->low_water_mark;
> +            mapping = qemu_vfio_add_mapping(s, host, size, index + 1, iova0);
> +            if (!mapping) {
> +                ret = -ENOMEM;
> +                goto out;
> +            }
> +            assert(qemu_vfio_verify_mappings(s));
> +            ret = qemu_vfio_do_mapping(s, host, size, iova0);
> +            if (ret) {
> +                qemu_vfio_undo_mapping(s, mapping, NULL);
> +                goto out;
> +            }
> +            s->low_water_mark += size;
> +            qemu_vfio_dump_mappings(s);
> +        } else {
> +            iova0 = s->high_water_mark - size;
> +            ret = qemu_vfio_do_mapping(s, host, size, iova0);
> +            if (ret) {
> +                goto out;
> +            }
> +            s->high_water_mark -= size;
> +        }
> +    }
> +    if (iova) {
> +        *iova = iova0;
> +    }
> +    qemu_mutex_unlock(&s->lock);
> +out:

Unlock needs to be here to avoid leaking the lock.

Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>

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