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Date: Tue, 28 Jun 2022 14:28:14 +0800
From: Baolu Lu <baolu.lu@...ux.intel.com>
To: Ethan Zhao <haifeng.zhao@...ux.intel.com>,
Joerg Roedel <joro@...tes.org>,
Jason Gunthorpe <jgg@...dia.com>,
Christoph Hellwig <hch@...radead.org>,
Kevin Tian <kevin.tian@...el.com>,
Ashok Raj <ashok.raj@...el.com>, Will Deacon <will@...nel.org>,
Robin Murphy <robin.murphy@....com>,
Jean-Philippe Brucker <jean-philippe@...aro.com>,
Dave Jiang <dave.jiang@...el.com>,
Vinod Koul <vkoul@...nel.org>
Cc: baolu.lu@...ux.intel.com, Eric Auger <eric.auger@...hat.com>,
Liu Yi L <yi.l.liu@...el.com>,
Jacob jun Pan <jacob.jun.pan@...el.com>,
iommu@...ts.linux-foundation.org, iommu@...ts.linux.dev,
linux-kernel@...r.kernel.org,
Jean-Philippe Brucker <jean-philippe@...aro.org>
Subject: Re: [PATCH v9 10/11] iommu: Per-domain I/O page fault handling
Hi Ethan,
On 2022/6/27 21:03, Ethan Zhao wrote:
> Hi,
>
> 在 2022/6/21 22:43, Lu Baolu 写道:
>> Tweak the I/O page fault handling framework to route the page faults to
>> the domain and call the page fault handler retrieved from the domain.
>> This makes the I/O page fault handling framework possible to serve more
>> usage scenarios as long as they have an IOMMU domain and install a page
>> fault handler in it. Some unused functions are also removed to avoid
>> dead code.
>>
>> The iommu_get_domain_for_dev_pasid() which retrieves attached domain
>> for a {device, PASID} pair is used. It will be used by the page fault
>> handling framework which knows {device, PASID} reported from the iommu
>> driver. We have a guarantee that the SVA domain doesn't go away during
>> IOPF handling, because unbind() waits for pending faults with
>> iopf_queue_flush_dev() before freeing the domain. Hence, there's no need
>> to synchronize life cycle of the iommu domains between the unbind() and
>> the interrupt threads.
>>
>> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
>> Reviewed-by: Jean-Philippe Brucker <jean-philippe@...aro.org>
>> ---
>> drivers/iommu/io-pgfault.c | 64 +++++---------------------------------
>> 1 file changed, 7 insertions(+), 57 deletions(-)
>>
>> diff --git a/drivers/iommu/io-pgfault.c b/drivers/iommu/io-pgfault.c
>> index aee9e033012f..4f24ec703479 100644
>> --- a/drivers/iommu/io-pgfault.c
>> +++ b/drivers/iommu/io-pgfault.c
>> @@ -69,69 +69,18 @@ static int iopf_complete_group(struct device *dev,
>> struct iopf_fault *iopf,
>> return iommu_page_response(dev, &resp);
>> }
>> -static enum iommu_page_response_code
>> -iopf_handle_single(struct iopf_fault *iopf)
>> -{
>> - vm_fault_t ret;
>> - struct mm_struct *mm;
>> - struct vm_area_struct *vma;
>> - unsigned int access_flags = 0;
>> - unsigned int fault_flags = FAULT_FLAG_REMOTE;
>> - struct iommu_fault_page_request *prm = &iopf->fault.prm;
>> - enum iommu_page_response_code status = IOMMU_PAGE_RESP_INVALID;
>> -
>> - if (!(prm->flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID))
>> - return status;
>> -
>> - mm = iommu_sva_find(prm->pasid);
>> - if (IS_ERR_OR_NULL(mm))
>> - return status;
>> -
>> - mmap_read_lock(mm);
>> -
>> - vma = find_extend_vma(mm, prm->addr);
>> - if (!vma)
>> - /* Unmapped area */
>> - goto out_put_mm;
>> -
>> - if (prm->perm & IOMMU_FAULT_PERM_READ)
>> - access_flags |= VM_READ;
>> -
>> - if (prm->perm & IOMMU_FAULT_PERM_WRITE) {
>> - access_flags |= VM_WRITE;
>> - fault_flags |= FAULT_FLAG_WRITE;
>> - }
>> -
>> - if (prm->perm & IOMMU_FAULT_PERM_EXEC) {
>> - access_flags |= VM_EXEC;
>> - fault_flags |= FAULT_FLAG_INSTRUCTION;
>> - }
>> -
>> - if (!(prm->perm & IOMMU_FAULT_PERM_PRIV))
>> - fault_flags |= FAULT_FLAG_USER;
>> -
>> - if (access_flags & ~vma->vm_flags)
>> - /* Access fault */
>> - goto out_put_mm;
>> -
>> - ret = handle_mm_fault(vma, prm->addr, fault_flags, NULL);
>> - status = ret & VM_FAULT_ERROR ? IOMMU_PAGE_RESP_INVALID :
>> - IOMMU_PAGE_RESP_SUCCESS;
>> -
>> -out_put_mm:
>> - mmap_read_unlock(mm);
>> - mmput(mm);
>> -
>> - return status;
>> -}
>> -
>
> Once the iopf_handle_single() is removed, the name of
> iopf_handle_group() looks a little weired
>
> and confused, does this group mean the iommu group (domain) ? while I
> take some minutes to
No. This is not the iommu group. It's page request group defined by the
PCI SIG spec. Multiple page requests could be put in a group with a
same group id. All page requests in a group could be responded to device
in one shot.
Best regards,
baolu
>
> look into the code, oh, means a batch / list / queue of iopfs , and
> iopf_handle_group() becomes a
>
> generic iopf_handler() .
>
> Doe it make sense to revise the names of iopf_handle_group(),
> iopf_complete_group, iopf_group in
>
> this patch set ?
>
>
> Thanks,
>
> Ethan
>
>> static void iopf_handle_group(struct work_struct *work)
>> {
>> struct iopf_group *group;
>> + struct iommu_domain *domain;
>> struct iopf_fault *iopf, *next;
>> enum iommu_page_response_code status = IOMMU_PAGE_RESP_SUCCESS;
>> group = container_of(work, struct iopf_group, work);
>> + domain = iommu_get_domain_for_dev_pasid(group->dev,
>> + group->last_fault.fault.prm.pasid);
>> + if (!domain || !domain->iopf_handler)
>> + status = IOMMU_PAGE_RESP_INVALID;
>> list_for_each_entry_safe(iopf, next, &group->faults, list) {
>> /*
>> @@ -139,7 +88,8 @@ static void iopf_handle_group(struct work_struct
>> *work)
>> * faults in the group if there is an error.
>> */
>> if (status == IOMMU_PAGE_RESP_SUCCESS)
>> - status = iopf_handle_single(iopf);
>> + status = domain->iopf_handler(&iopf->fault,
>> + domain->fault_data);
>> if (!(iopf->fault.prm.flags &
>> IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE))
>
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