linux-kernel - Re: [PATCH v5 09/12] iommu: Make iommu_queue

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Date:   Thu, 21 Sep 2023 20:34:02 -0300
From:   Jason Gunthorpe <jgg@...pe.ca>
To:     "Liu, Jingqi" <jingqi.liu@...el.com>
Cc:     Lu Baolu <baolu.lu@...ux.intel.com>,
        Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Kevin Tian <kevin.tian@...el.com>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>,
        Nicolin Chen <nicolinc@...dia.com>,
        Yi Liu <yi.l.liu@...el.com>,
        Jacob Pan <jacob.jun.pan@...ux.intel.com>,
        iommu@...ts.linux.dev, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 09/12] iommu: Make iommu_queue_iopf() more generic

On Thu, Sep 21, 2023 at 11:25:56PM +0800, Liu, Jingqi wrote:
> 
> On 9/14/2023 4:56 PM, Lu Baolu wrote:
> > Make iommu_queue_iopf() more generic by making the iopf_group a minimal
> > set of iopf's that an iopf handler of domain should handle and respond
> > to. Add domain parameter to struct iopf_group so that the handler can
> > retrieve and use it directly.
> > 
> > Change iommu_queue_iopf() to forward groups of iopf's to the domain's
> > iopf handler. This is also a necessary step to decouple the sva iopf
> > handling code from this interface.
> > 
> > Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
> > ---
> >   include/linux/iommu.h      |  4 ++--
> >   drivers/iommu/iommu-sva.h  |  6 ++---
> >   drivers/iommu/io-pgfault.c | 49 ++++++++++++++++++++++++++++----------
> >   drivers/iommu/iommu-sva.c  |  3 +--
> >   4 files changed, 42 insertions(+), 20 deletions(-)
> > 
> ......
> 
> > @@ -112,6 +110,7 @@ int iommu_queue_iopf(struct iommu_fault *fault, struct device *dev)
> >   {
> >   	int ret;
> >   	struct iopf_group *group;
> > +	struct iommu_domain *domain;
> >   	struct iopf_fault *iopf, *next;
> >   	struct iommu_fault_param *iopf_param;
> >   	struct dev_iommu *param = dev->iommu;
> > @@ -143,6 +142,19 @@ int iommu_queue_iopf(struct iommu_fault *fault, struct device *dev)
> >   		return 0;
> >   	}
> > +	if (fault->prm.flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID)
> > +		domain = iommu_get_domain_for_dev_pasid(dev, fault->prm.pasid, 0);
> > +	else
> > +		domain = iommu_get_domain_for_dev(dev);
> > +
> > +	if (!domain || !domain->iopf_handler) {
> 
> Does it need to check if 'domain' is error ?  Like below:
> 
>          if (!domain || IS_ERR(domain) || !domain->iopf_handler)

Urk, yes, but not like that

The IF needs to be moved into the else block as each individual
function has its own return convention.

Jason