Messages in this thread | | | Date | Thu, 19 May 2022 17:40:21 +0100 | From | Jean-Philippe Brucker <> | Subject | Re: [PATCH v7 08/10] iommu: Prepare IOMMU domain for IOPF |
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On Thu, May 19, 2022 at 03:20:45PM +0800, 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. > > Suggested-by: Jean-Philippe Brucker <jean-philippe@linaro.org> > Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> > --- > include/linux/iommu.h | 3 ++ > drivers/iommu/io-pgfault.c | 7 ++++ > drivers/iommu/iommu-sva-lib.c | 65 +++++++++++++++++++++++++++++++++++ > 3 files changed, 75 insertions(+) > > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > index e4ce2fe0e144..45f274b2640d 100644 > --- a/include/linux/iommu.h > +++ b/include/linux/iommu.h > @@ -100,6 +100,9 @@ struct iommu_domain { > void *handler_token; > 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; > }; > > static inline bool iommu_is_dma_domain(struct iommu_domain *domain) > 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 568e0f64edac..317ab8e8c149 100644 > --- a/drivers/iommu/iommu-sva-lib.c > +++ b/drivers/iommu/iommu-sva-lib.c > @@ -72,6 +72,69 @@ struct mm_struct *iommu_sva_find(ioasid_t pasid) > } > EXPORT_SYMBOL_GPL(iommu_sva_find); > > +/* > + * I/O page fault handler for SVA > + * > + * Copied from io-pgfault.c with mmget_not_zero() added before > + * mmap_read_lock().
Comment doesn't really belong here, maybe better in the commit message. Apart from that
Reviewed-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
> + */ > +static enum iommu_page_response_code > +iommu_sva_handle_iopf(struct iommu_fault *fault, void *data) > +{ > + vm_fault_t ret; > + struct mm_struct *mm; > + struct vm_area_struct *vma; > + unsigned int access_flags = 0; > + struct iommu_domain *domain = data; > + 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; > + > + mm = domain_to_mm(domain); > + if (IS_ERR_OR_NULL(mm) || !mmget_not_zero(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; > +} > + > /* > * IOMMU SVA driver-oriented interfaces > */ > @@ -94,6 +157,8 @@ iommu_sva_alloc_domain(struct bus_type *bus, struct mm_struct *mm) > domain = &sva_domain->domain; > domain->type = IOMMU_DOMAIN_SVA; > domain->ops = bus->iommu_ops->sva_domain_ops; > + domain->iopf_handler = iommu_sva_handle_iopf; > + domain->fault_data = domain; > > return domain; > } > -- > 2.25.1 >
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