Re: [PATCH v6 06/21] vfio/iommufd: Add support for iova_ranges and pgsizes

["Cédric Le Goater" <clg@redhat.com>]

On 11/14/23 11:09, Zhenzhong Duan wrote:
> Some vIOMMU such as virtio-iommu use IOVA ranges from host side to
> setup reserved ranges for passthrough device, so that guest will not
> use an IOVA range beyond host support.
> 
> Use an uAPI of IOMMUFD to get IOVA ranges of host side and pass to
> vIOMMU just like the legacy backend, if this fails, fallback to
> 64bit IOVA range.
> 
> Also use out_iova_alignment returned from uAPI as pgsizes instead of
> qemu_real_host_page_size() as a fallback.
> 
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
> ---
> v6: propagate iommufd_cdev_get_info_iova_range err and print as warning
> 
>   hw/vfio/iommufd.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++-
>   1 file changed, 54 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/vfio/iommufd.c b/hw/vfio/iommufd.c
> index 06282d885c..e5bf528e89 100644
> --- a/hw/vfio/iommufd.c
> +++ b/hw/vfio/iommufd.c
> @@ -267,6 +267,53 @@ static int iommufd_cdev_ram_block_discard_disable(bool state)
>       return ram_block_uncoordinated_discard_disable(state);
>   }
>   
> +static int iommufd_cdev_get_info_iova_range(VFIOIOMMUFDContainer *container,
> +                                            uint32_t ioas_id, Error **errp)
> +{
> +    VFIOContainerBase *bcontainer = &container->bcontainer;
> +    struct iommu_ioas_iova_ranges *info;
> +    struct iommu_iova_range *iova_ranges;
> +    int ret, sz, fd = container->be->fd;
> +
> +    info = g_malloc0(sizeof(*info));
> +    info->size = sizeof(*info);
> +    info->ioas_id = ioas_id;
> +
> +    ret = ioctl(fd, IOMMU_IOAS_IOVA_RANGES, info);
> +    if (ret && errno != EMSGSIZE) {
> +        goto error;
> +    }
> +
> +    sz = info->num_iovas * sizeof(struct iommu_iova_range);
> +    info = g_realloc(info, sizeof(*info) + sz);
> +    info->allowed_iovas = (uintptr_t)(info + 1);
> +
> +    ret = ioctl(fd, IOMMU_IOAS_IOVA_RANGES, info);
> +    if (ret) {
> +        goto error;
> +    }
> +
> +    iova_ranges = (struct iommu_iova_range *)(uintptr_t)info->allowed_iovas;
> +
> +    for (int i = 0; i < info->num_iovas; i++) {
> +        Range *range = g_new(Range, 1);
> +
> +        range_set_bounds(range, iova_ranges[i].start, iova_ranges[i].last);
> +        bcontainer->iova_ranges =
> +            range_list_insert(bcontainer->iova_ranges, range);
> +    }
> +    bcontainer->pgsizes = info->out_iova_alignment;
> +
> +    g_free(info);
> +    return 0;
> +
> +error:
> +    ret = -errno;
> +    g_free(info);
> +    error_setg_errno(errp, errno, "Cannot get IOVA ranges");
> +    return ret;
> +}
> +
>   static int iommufd_cdev_attach(const char *name, VFIODevice *vbasedev,
>                                  AddressSpace *as, Error **errp)
>   {
> @@ -341,7 +388,13 @@ static int iommufd_cdev_attach(const char *name, VFIODevice *vbasedev,
>           goto err_discard_disable;
>       }
>   
> -    bcontainer->pgsizes = qemu_real_host_page_size();
> +    ret = iommufd_cdev_get_info_iova_range(container, ioas_id, &err);
> +    if (ret) {
> +        warn_report_err(err);
> +        err = NULL;
> +        error_printf("Fallback to default 64bit IOVA range and 4K page size\n");

This would be better :

         error_append_hint(&err,
                    "Fallback to default 64bit IOVA range and 4K page size\n");
         warn_report_err(err);

I will take care of it if you agree. With that,

Reviewed-by: Cédric Le Goater <clg@redhat.com>

Thanks,

C.


> +        bcontainer->pgsizes = qemu_real_host_page_size();
> +    }
>   
>       bcontainer->listener = vfio_memory_listener;
>       memory_listener_register(&bcontainer->listener, bcontainer->space->as);