From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jason Gunthorpe <jgg@nvidia.com>
Date: Tue, 05 Jul 2022 11:57:51 +0000
Subject: Re: [PATCH kernel] powerpc/iommu: Add simple iommu_ops to report capabilities
Message-Id: <YsQnP/jBG22FnPMA@nvidia.com>
List-Id: <kvm-ppc.vger.kernel.org>
References: <20220705062235.2276125-1-aik@ozlabs.ru>
In-Reply-To: <20220705062235.2276125-1-aik@ozlabs.ru>
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-Transfer-Encoding: 7bit
To: Alexey Kardashevskiy <aik@ozlabs.ru>
Cc: linuxppc-dev@lists.ozlabs.org, Robin Murphy <robin.murphy@arm.com>, Michael Ellerman <mpe@ellerman.id.au>, Lu Baolu <baolu.lu@linux.intel.com>, Kevin Tian <kevin.tian@intel.com>, Joerg Roedel <jroedel@suse.de>, Fabiano Rosas <farosas@linux.ibm.com>, Daniel Henrique Barboza <danielhb413@gmail.com>, Murilo Opsfelder Araujo <muriloo@linux.ibm.com>, Alex Williamson <alex.williamson@redhat.com>, kvm-ppc@vger.kernel.org, kvm@vger.kernel.org, iommu@lists.linux-foundation.org

On Tue, Jul 05, 2022 at 04:22:35PM +1000, Alexey Kardashevskiy wrote:

> I have not looked into the domains for ages, what is missing here? With this
> on top of 5.19-rc1 VFIO works again on my POWER9 box. Thanks,

Does this solve all the problems or just coherency? It seems like it
should solve everything now as there will be a IOMMU_DOMAIN_BLOCKED
and the ref logic will succeed to assign it?

> +static struct iommu_domain *spapr_tce_iommu_domain_alloc(unsigned int type)
> +{
> +	struct iommu_domain *domain = kzalloc(sizeof(*domain), GFP_KERNEL);
> +
> +	if (!domain)
> +		return NULL;

This should only succeed if type is IOMMU_DOMAIN_BLOCKED

> +static struct iommu_group *spapr_tce_iommu_device_group(struct device *dev)
> +{
> +	struct iommu_group *grp = dev->iommu_group;
> +
> +	if (!grp)
> +		grp = ERR_PTR(-ENODEV);

It looks like this should just always fail since the code code already
checks iommu_group before calling this? (Arguably ppc should be
refactored to use the normal probe_device and device_group ops to
create groups, but that doesn't seem critical for this.

Thanks
Jason