Re: [PATCH v3 24/25] iommu/dma: Factor out flush queue init

From: Will Deacon
Date: Mon Aug 09 2021 - 08:52:46 EST


On Wed, Aug 04, 2021 at 06:15:52PM +0100, Robin Murphy wrote:
> Factor out flush queue setup from the initial domain init so that we
> can potentially trigger it from sysfs later on in a domain's lifetime.
>
> Reviewed-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
> Reviewed-by: John Garry <john.garry@xxxxxxxxxx>
> Signed-off-by: Robin Murphy <robin.murphy@xxxxxxx>
> ---
> drivers/iommu/dma-iommu.c | 30 ++++++++++++++++++++----------
> include/linux/dma-iommu.h | 9 ++++++---
> 2 files changed, 26 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> index 2e19505dddf9..f51b8dc99ac6 100644
> --- a/drivers/iommu/dma-iommu.c
> +++ b/drivers/iommu/dma-iommu.c
> @@ -310,6 +310,25 @@ static bool dev_is_untrusted(struct device *dev)
> return dev_is_pci(dev) && to_pci_dev(dev)->untrusted;
> }
>
> +int iommu_dma_init_fq(struct iommu_domain *domain)
> +{
> + struct iommu_dma_cookie *cookie = domain->iova_cookie;
> +
> + if (domain->type != IOMMU_DOMAIN_DMA_FQ)
> + return -EINVAL;
> + if (cookie->fq_domain)
> + return 0;
> +
> + if (init_iova_flush_queue(&cookie->iovad, iommu_dma_flush_iotlb_all,
> + iommu_dma_entry_dtor)) {
> + pr_warn("iova flush queue initialization failed\n");
> + domain->type = IOMMU_DOMAIN_DMA;
> + return -ENODEV;

I do find this a bit odd: we assert that the caller has set domain->type
to IOMMU_DOMAIN_DMA_FQ but then on failure we reset it to IOMMU_DOMAIN_DMA
here. I think it would be less error-prone if the setting of domain->type
was handled in the same function.

Will