linux-kernel - Re: [PATCH v3 15/21] iommu/vt-d: Add helper to allocate paging domain

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Message-ID: <d4cfdc8f-12a4-44d1-85ee-ce05dd88b3e3@linux.intel.com>
Date: Thu, 20 Jun 2024 09:14:24 +0800
From: Baolu Lu <baolu.lu@...ux.intel.com>
To: Jason Gunthorpe <jgg@...pe.ca>
Cc: 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>, Yi Liu <yi.l.liu@...el.com>,
 David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
 Kalle Valo <kvalo@...nel.org>, Bjorn Andersson <andersson@...nel.org>,
 Mathieu Poirier <mathieu.poirier@...aro.org>,
 Alex Williamson <alex.williamson@...hat.com>, mst@...hat.com,
 Jason Wang <jasowang@...hat.com>, Thierry Reding <thierry.reding@...il.com>,
 Jonathan Hunter <jonathanh@...dia.com>,
 Mikko Perttunen <mperttunen@...dia.com>,
 Jeff Johnson <quic_jjohnson@...cinc.com>, ath10k@...ts.infradead.org,
 ath11k@...ts.infradead.org, iommu@...ts.linux.dev,
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 15/21] iommu/vt-d: Add helper to allocate paging domain

On 6/19/24 11:12 PM, Jason Gunthorpe wrote:
> On Mon, Jun 10, 2024 at 04:55:49PM +0800, Lu Baolu wrote:
>> The domain_alloc_user operation is currently implemented by allocating a
>> paging domain using iommu_domain_alloc(). This is because it needs to fully
>> initialize the domain before return. Add a helper to do this to avoid using
>> iommu_domain_alloc().
>>
>> Signed-off-by: Lu Baolu<baolu.lu@...ux.intel.com>
>> ---
>>   drivers/iommu/intel/iommu.c | 87 +++++++++++++++++++++++++++++++++----
>>   1 file changed, 78 insertions(+), 9 deletions(-)
> It seems Ok, but I have some small thoughts
> 
> Reviewed-by: Jason Gunthorpe<jgg@...dia.com>
> 
>> diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
>> index 2e9811bf2a4e..ccde5f5972e4 100644
>> --- a/drivers/iommu/intel/iommu.c
>> +++ b/drivers/iommu/intel/iommu.c
>> @@ -3633,6 +3633,79 @@ static struct iommu_domain blocking_domain = {
>>   	}
>>   };
>>   
>> +static int iommu_superpage_capability(struct intel_iommu *iommu, bool first_stage)
>> +{
>> +	if (!intel_iommu_superpage)
>> +		return 0;
>> +
>> +	if (first_stage)
>> +		return cap_fl1gp_support(iommu->cap) ? 2 : 1;
>> +
>> +	return fls(cap_super_page_val(iommu->cap));
>> +}
>> +
>> +static struct dmar_domain *paging_domain_alloc(struct device *dev, bool first_stage)
>> +{
>> +	struct device_domain_info *info = dev_iommu_priv_get(dev);
>> +	struct intel_iommu *iommu = info->iommu;
>> +	struct dmar_domain *domain;
>> +	int addr_width;
>> +
>> +	domain = kzalloc(sizeof(*domain), GFP_KERNEL);
>> +	if (!domain)
>> +		return ERR_PTR(-ENOMEM);
>> +
>> +	INIT_LIST_HEAD(&domain->devices);
>> +	INIT_LIST_HEAD(&domain->dev_pasids);
>> +	INIT_LIST_HEAD(&domain->cache_tags);
>> +	spin_lock_init(&domain->lock);
>> +	spin_lock_init(&domain->cache_lock);
>> +	xa_init(&domain->iommu_array);
> You should probably split more, with an 'alloc struct dmar_domain'
> function that can be used by SVA and others too.
> 
>> +	domain->nid = dev_to_node(dev);
>> +	domain->has_iotlb_device = info->ats_enabled;
>> +	domain->use_first_level = first_stage;
>> +
>> +	/* calculate the address width */
>> +	addr_width = agaw_to_width(iommu->agaw);
>> +	if (addr_width > cap_mgaw(iommu->cap))
>> +		addr_width = cap_mgaw(iommu->cap);
>> +	domain->gaw = addr_width;
>> +	domain->agaw = iommu->agaw;
>> +	domain->max_addr = __DOMAIN_MAX_ADDR(addr_width);
>> +
>> +	/* iommu memory access coherency */
>> +	domain->iommu_coherency = iommu_paging_structure_coherency(iommu);
>> +
>> +	/* pagesize bitmap */
>> +	domain->domain.pgsize_bitmap = SZ_4K;
>> +	domain->iommu_superpage = iommu_superpage_capability(iommu, first_stage);
>> +	domain->domain.pgsize_bitmap |= domain_super_pgsize_bitmap(domain);
> Then some of this stuff is really just paging only. Like
> SVA/identity/etc don't have pgszie and other things.

Yeah, good suggestion. I could do this in this series if it needs a new
version or in my next series which will add domain_alloc_paging for the
intel driver.

Best regards,
baolu