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Date: Sun, 31 Jul 2022 21:47:44 +0800
From: Baolu Lu <baolu.lu@...ux.intel.com>
To: Yi Liu <yi.l.liu@...el.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>,
Jacob jun Pan <jacob.jun.pan@...el.com>,
Zhangfei Gao <zhangfei.gao@...aro.org>,
Zhu Tony <tony.zhu@...el.com>, iommu@...ts.linux.dev,
linux-kernel@...r.kernel.org,
Jean-Philippe Brucker <jean-philippe@...aro.org>
Subject: Re: [PATCH v10 10/12] iommu: Prepare IOMMU domain for IOPF
On 2022/7/31 20:50, Yi Liu wrote:
> On 2022/7/5 13:07, Lu Baolu wrote:
>> This adds some mechanisms around the iommu_domain so that the I/O page
>> fault handling framework could route a page fault to the domain and
>> call the fault handler from it.
>>
>> Add pointers to the page fault handler and its private data in struct
>> iommu_domain. The fault handler will be called with the private data
>> as a parameter once a page fault is routed to the domain. Any kernel
>> component which owns an iommu domain could install handler and its
>> private parameter so that the page fault could be further routed and
>> handled.
>>
>> This also prepares the SVA implementation to be the first consumer of
>> the per-domain page fault handling model. The I/O page fault handler
>> for SVA is copied to the SVA file with mmget_not_zero() added before
>> mmap_read_lock().
>>
>> Suggested-by: Jean-Philippe Brucker <jean-philippe@...aro.org>
>> Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
>> Reviewed-by: Jean-Philippe Brucker <jean-philippe@...aro.org>
>> Tested-by: Zhangfei Gao <zhangfei.gao@...aro.org>
>> Tested-by: Tony Zhu <tony.zhu@...el.com>
>> ---
>> include/linux/iommu.h | 3 ++
>> drivers/iommu/iommu-sva-lib.h | 8 +++++
>> drivers/iommu/io-pgfault.c | 7 +++++
>> drivers/iommu/iommu-sva-lib.c | 58 +++++++++++++++++++++++++++++++++++
>> drivers/iommu/iommu.c | 4 +++
>> 5 files changed, 80 insertions(+)
>>
>> diff --git a/include/linux/iommu.h b/include/linux/iommu.h
>> index ae0cfca064e6..47610f21d451 100644
>> --- a/include/linux/iommu.h
>> +++ b/include/linux/iommu.h
>> @@ -105,6 +105,9 @@ struct iommu_domain {
>> unsigned long pgsize_bitmap; /* Bitmap of page sizes in use */
>> struct iommu_domain_geometry geometry;
>> struct iommu_dma_cookie *iova_cookie;
>> + enum iommu_page_response_code (*iopf_handler)(struct iommu_fault
>> *fault,
>> + void *data);
>> + void *fault_data;
>> union {
>> struct {
>> iommu_fault_handler_t handler;
>> diff --git a/drivers/iommu/iommu-sva-lib.h
>> b/drivers/iommu/iommu-sva-lib.h
>> index 8909ea1094e3..1b3ace4b5863 100644
>> --- a/drivers/iommu/iommu-sva-lib.h
>> +++ b/drivers/iommu/iommu-sva-lib.h
>> @@ -26,6 +26,8 @@ int iopf_queue_flush_dev(struct device *dev);
>> struct iopf_queue *iopf_queue_alloc(const char *name);
>> void iopf_queue_free(struct iopf_queue *queue);
>> int iopf_queue_discard_partial(struct iopf_queue *queue);
>> +enum iommu_page_response_code
>> +iommu_sva_handle_iopf(struct iommu_fault *fault, void *data);
>> #else /* CONFIG_IOMMU_SVA */
>> static inline int iommu_queue_iopf(struct iommu_fault *fault, void
>> *cookie)
>> @@ -63,5 +65,11 @@ static inline int iopf_queue_discard_partial(struct
>> iopf_queue *queue)
>> {
>> return -ENODEV;
>> }
>> +
>> +static inline enum iommu_page_response_code
>> +iommu_sva_handle_iopf(struct iommu_fault *fault, void *data)
>> +{
>> + return IOMMU_PAGE_RESP_INVALID;
>> +}
>> #endif /* CONFIG_IOMMU_SVA */
>> #endif /* _IOMMU_SVA_LIB_H */
>> diff --git a/drivers/iommu/io-pgfault.c b/drivers/iommu/io-pgfault.c
>> index 1df8c1dcae77..aee9e033012f 100644
>> --- a/drivers/iommu/io-pgfault.c
>> +++ b/drivers/iommu/io-pgfault.c
>> @@ -181,6 +181,13 @@ static void iopf_handle_group(struct work_struct
>> *work)
>> * request completes, outstanding faults will have been dealt with
>> by the time
>> * the PASID is freed.
>> *
>> + * Any valid page fault will be eventually routed to an iommu domain
>> and the
>> + * page fault handler installed there will get called. The users of this
>> + * handling framework should guarantee that the iommu domain could
>> only be
>> + * freed after the device has stopped generating page faults (or the
>> iommu
>> + * hardware has been set to block the page faults) and the pending
>> page faults
>> + * have been flushed.
>> + *
>> * Return: 0 on success and <0 on error.
>> */
>> int iommu_queue_iopf(struct iommu_fault *fault, void *cookie)
>> diff --git a/drivers/iommu/iommu-sva-lib.c
>> b/drivers/iommu/iommu-sva-lib.c
>> index 751366980232..536d34855c74 100644
>> --- a/drivers/iommu/iommu-sva-lib.c
>> +++ b/drivers/iommu/iommu-sva-lib.c
>> @@ -167,3 +167,61 @@ u32 iommu_sva_get_pasid(struct iommu_sva *handle)
>> return domain->mm->pasid;
>> }
>> EXPORT_SYMBOL_GPL(iommu_sva_get_pasid);
>> +
>> +/*
>> + * I/O page fault handler for SVA
>> + */
>> +enum iommu_page_response_code
>> +iommu_sva_handle_iopf(struct iommu_fault *fault, void *data)
>> +{
>> + vm_fault_t ret;
>> + struct vm_area_struct *vma;
>> + struct mm_struct *mm = data;
>> + unsigned int access_flags = 0;
>> + unsigned int fault_flags = FAULT_FLAG_REMOTE;
>> + struct iommu_fault_page_request *prm = &fault->prm;
>> + enum iommu_page_response_code status = IOMMU_PAGE_RESP_INVALID;
>> +
>> + if (!(prm->flags & IOMMU_FAULT_PAGE_REQUEST_PASID_VALID))
>> + return status;
>> +
>> + if (IS_ERR_OR_NULL(mm) || !mmget_not_zero(mm))
>
> is it possible to be ERR or NULL? The mm life circle should have been
> guaranteed by the mmgrab() in iommu_sva_domain_alloc(). Perhaps coding
> issue if it happens. :-)
Updated. Thanks!
Best regards,
baolu
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