linux-kernel - Re: [PATCH v4 10/19] iommu: Add set_platform_dma

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Message-ID: <5ce5a6a4-9397-9665-7352-862d89b3f228@linux.intel.com>
Date:   Sat, 7 Jan 2023 10:48:31 +0800
From:   Baolu Lu <baolu.lu@...ux.intel.com>
To:     Jason Gunthorpe <jgg@...dia.com>
Cc:     Joerg Roedel <joro@...tes.org>,
        Christoph Hellwig <hch@...radead.org>,
        Kevin Tian <kevin.tian@...el.com>,
        Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>,
        Suravee Suthikulpanit <suravee.suthikulpanit@....com>,
        Hector Martin <marcan@...can.st>,
        Sven Peter <sven@...npeter.dev>,
        Rob Clark <robdclark@...il.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Yong Wu <yong.wu@...iatek.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Heiko Stuebner <heiko@...ech.de>,
        Matthew Rosato <mjrosato@...ux.ibm.com>,
        Orson Zhai <orsonzhai@...il.com>,
        Baolin Wang <baolin.wang@...ux.alibaba.com>,
        Chunyan Zhang <zhang.lyra@...il.com>,
        Chen-Yu Tsai <wens@...e.org>,
        Thierry Reding <thierry.reding@...il.com>,
        iommu@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 10/19] iommu: Add set_platform_dma_ops iommu ops

On 1/6/2023 10:26 PM, Jason Gunthorpe wrote:
> On Fri, Jan 06, 2023 at 02:07:32PM +0800, Baolu Lu wrote:
> 
>> Above looks good to me. Thanks! I have updated this part of code like
>> below:
>>
>> @@ -2177,10 +2188,20 @@ static int __iommu_group_set_domain(struct
>> iommu_group *group,
>>           * platform specific behavior.
>>           */
>>          if (!new_domain) {
>> -               if (WARN_ON(!group->domain->ops->detach_dev))
>> -                       return -EINVAL;
>> -               __iommu_group_for_each_dev(group, group->domain,
>> -                                          iommu_group_do_detach_device);
>> +               struct group_device *grp_dev;
>> +
>> +               grp_dev = list_first_entry(&group->devices,
>> +                                          struct group_device, list);
> It seems OK - I hope we naturally can't ever get in a situation where
> a group has disjoint iommu drivers.

The final code after cleanup looks like below. We will WARN_ON the lack
of callback in the iommu_group_do_set_platform_dma() helper.

2152 static int iommu_group_do_set_platform_dma(struct device *dev, void 
*data)
2153 {
2154         const struct iommu_ops *ops = dev_iommu_ops(dev);
2155
2156         if (!WARN_ON(!ops->set_platform_dma_ops))
2157                 ops->set_platform_dma_ops(dev);
2158
2159         return 0;
2160 }
2161
2162 static int __iommu_group_set_domain(struct iommu_group *group,
2163                                     struct iommu_domain *new_domain)
2164 {
2165         int ret;
2166
2167         if (group->domain == new_domain)
2168                 return 0;
2169
2170         /*
2171          * New drivers should support default domains, so 
set_platform_dma()
2172          * op will never be called. Otherwise the NULL domain 
represents some
2173          * platform specific behavior.
2174          */
2175         if (!new_domain) {
2176                 __iommu_group_for_each_dev(group, NULL,
2177 
iommu_group_do_set_platform_dma);
2178                 group->domain = NULL;
2179                 return 0;
2180         }

How do you like this?

--
Best regards,
baolu