linux-kernel - Re: [PATCH v14 10/22] vfio iommu type1: Add support for mediated devices

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Message-ID: <20161116165715.5da8f734@t450s.home>
Date:   Wed, 16 Nov 2016 16:57:15 -0700
From:   Alex Williamson <alex.williamson@...hat.com>
To:     Kirti Wankhede <kwankhede@...dia.com>
Cc:     <pbonzini@...hat.com>, <kraxel@...hat.com>, <cjia@...dia.com>,
        <qemu-devel@...gnu.org>, <kvm@...r.kernel.org>,
        <kevin.tian@...el.com>, <jike.song@...el.com>,
        <bjsdjshi@...ux.vnet.ibm.com>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v14 10/22] vfio iommu type1: Add support for mediated
 devices

On Thu, 17 Nov 2016 02:16:22 +0530
Kirti Wankhede <kwankhede@...dia.com> wrote:
> @@ -931,6 +1344,24 @@ static void vfio_iommu_type1_detach_group(void *iommu_data,
>  
>  	mutex_lock(&iommu->lock);
>  
> +	if (iommu->external_domain) {
> +		group = find_iommu_group(iommu->external_domain, iommu_group);
> +		if (group) {
> +			list_del(&group->next);
> +			kfree(group);
> +
> +			if (list_empty(&iommu->external_domain->group_list)) {
> +				vfio_sanity_check_pfn_list(iommu);
> +
> +				if (!IS_IOMMU_CAP_DOMAIN_IN_CONTAINER(iommu))
> +					vfio_iommu_unmap_unpin_all(iommu);
> +
> +				kfree(iommu->external_domain);

I advised in one place that I didn't understand why  we were checking
iommu->external_domain before walking the pfn_list, but we do have
several checks still in place for if(iommu->external_domain), so I
think we better be setting to NULL after we free it.

I haven't finished my review yet, but if this ends up being the only
comment and you agree, I can add:

iommu->external_domain = NULL;

here on commit.  Thanks,

Alex