linux-kernel - Re: [PATCH v1 6/8] gpu/host1x: Use iommu_attach/detach

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Message-ID: <0c80f52e-0529-b299-6f13-105f873be3a0@linux.intel.com>
Date:   Fri, 7 Jan 2022 09:19:11 +0800
From:   Lu Baolu <baolu.lu@...ux.intel.com>
To:     Jason Gunthorpe <jgg@...dia.com>
Cc:     baolu.lu@...ux.intel.com, Joerg Roedel <joro@...tes.org>,
        Alex Williamson <alex.williamson@...hat.com>,
        Robin Murphy <robin.murphy@....com>,
        Christoph Hellwig <hch@...radead.org>,
        Kevin Tian <kevin.tian@...el.com>,
        Ashok Raj <ashok.raj@...el.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Will Deacon <will@...nel.org>,
        Dan Williams <dan.j.williams@...el.com>, rafael@...nel.org,
        Diana Craciun <diana.craciun@....nxp.com>,
        Cornelia Huck <cohuck@...hat.com>,
        Eric Auger <eric.auger@...hat.com>,
        Liu Yi L <yi.l.liu@...el.com>,
        Jacob jun Pan <jacob.jun.pan@...el.com>,
        Chaitanya Kulkarni <kch@...dia.com>,
        Stuart Yoder <stuyoder@...il.com>,
        Laurentiu Tudor <laurentiu.tudor@....com>,
        Thierry Reding <thierry.reding@...il.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Li Yang <leoyang.li@....com>,
        Dmitry Osipenko <digetx@...il.com>,
        iommu@...ts.linux-foundation.org, linux-pci@...r.kernel.org,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1 6/8] gpu/host1x: Use iommu_attach/detach_device()

On 1/7/22 8:48 AM, Jason Gunthorpe wrote:
> On Fri, Jan 07, 2022 at 08:35:34AM +0800, Lu Baolu wrote:
>> On 1/6/22 11:35 PM, Jason Gunthorpe wrote:
>>> On Thu, Jan 06, 2022 at 10:20:51AM +0800, Lu Baolu wrote:
>>>> Ordinary drivers should use iommu_attach/detach_device() for domain
>>>> attaching and detaching.
>>>>
>>>> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
>>>>    drivers/gpu/host1x/dev.c | 4 ++--
>>>>    1 file changed, 2 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/host1x/dev.c b/drivers/gpu/host1x/dev.c
>>>> index fbb6447b8659..6e08cb6202cc 100644
>>>> +++ b/drivers/gpu/host1x/dev.c
>>>> @@ -265,7 +265,7 @@ static struct iommu_domain *host1x_iommu_attach(struct host1x *host)
>>>>    			goto put_cache;
>>>>    		}
>>>> -		err = iommu_attach_group(host->domain, host->group);
>>>> +		err = iommu_attach_device(host->domain, host->dev);
>>>>    		if (err) {
>>>>    			if (err == -ENODEV)
>>>>    				err = 0;
>>>> @@ -335,7 +335,7 @@ static void host1x_iommu_exit(struct host1x *host)
>>>>    {
>>>>    	if (host->domain) {
>>>>    		put_iova_domain(&host->iova);
>>>> -		iommu_detach_group(host->domain, host->group);
>>>> +		iommu_detach_device(host->domain, host->dev);
>>>>    		iommu_domain_free(host->domain);
>>>>    		host->domain = NULL;
>>>
>>> Shouldn't this add the flag to tegra_host1x_driver ?
>>
>> This is called for a single driver. The call trace looks like below:
>>
>> static struct platform_driver tegra_host1x_driver = {
>>          .driver = {
>>                  .name = "tegra-host1x",
>>                  .of_match_table = host1x_of_match,
>>          },
>>          .probe = host1x_probe,
>>          .remove = host1x_remove,
>> };
>>
>> host1x_probe(dev)
>> ->host1x_iommu_init(host)	//host is a wrapper of dev
>>       iommu_domain_alloc(&platform_bus_type)
>>       iommu_attach_group(domain, group);
> 
> The main question is if the iommu group is being shared with other
> drivers, not the call chain for this function.
> 
> For tegra you have to go look in each entry of the of_match_table:
> 
>          { .compatible = "nvidia,tegra114-host1x", .data = &host1x02_info, },
> 
> And find the DTS block:
> 
>          host1x@...00000 {
>                  compatible = "nvidia,tegra114-host1x";
>                  reg = <0x50000000 0x00028000>;
>                  interrupts = <GIC_SPI 65 IRQ_TYPE_LEVEL_HIGH>, /* syncpt */
>                               <GIC_SPI 67 IRQ_TYPE_LEVEL_HIGH>; /* general */
>                  interrupt-names = "syncpt", "host1x";
>                  clocks = <&tegra_car TEGRA114_CLK_HOST1X>;
>                  clock-names = "host1x";
>                  resets = <&tegra_car 28>;
>                  reset-names = "host1x";
>                  iommus = <&mc TEGRA_SWGROUP_HC>;
> 
> Then check if any other devices in the DTS use the same 'iommus' which
> is how the groups are setup.

Yes, exactly.

> 
> I checked everything and it does look like this is a single device
> group.

Okay, thanks!

> 
> Jason
> 

Best regards,
baolu