Messages in this thread |  | | Subject | Re: [PATCH v3 3/4] iommu/vt-d: Report page request faults for guest SVA | From | Lu Baolu <> | Date | Fri, 10 Jul 2020 13:25:33 +0800 |
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Hi Kevin,
On 2020/7/10 10:24, Tian, Kevin wrote: >> From: Lu Baolu <baolu.lu@linux.intel.com> >> Sent: Thursday, July 9, 2020 3:06 PM >> >> A pasid might be bound to a page table from a VM guest via the iommu >> ops.sva_bind_gpasid. In this case, when a DMA page fault is detected >> on the physical IOMMU, we need to inject the page fault request into >> the guest. After the guest completes handling the page fault, a page >> response need to be sent back via the iommu ops.page_response(). >> >> This adds support to report a page request fault. Any external module >> which is interested in handling this fault should regiester a notifier >> with iommu_register_device_fault_handler(). >> >> Co-developed-by: Jacob Pan <jacob.jun.pan@linux.intel.com> >> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com> >> Co-developed-by: Liu Yi L <yi.l.liu@intel.com> >> Signed-off-by: Liu Yi L <yi.l.liu@intel.com> >> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com> >> --- >> drivers/iommu/intel/svm.c | 103 +++++++++++++++++++++++++++++++------- >> 1 file changed, 85 insertions(+), 18 deletions(-) >> >> diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c >> index c23167877b2b..d24e71bac8db 100644 >> --- a/drivers/iommu/intel/svm.c >> +++ b/drivers/iommu/intel/svm.c >> @@ -815,8 +815,63 @@ static void intel_svm_drain_prq(struct device *dev, >> int pasid) >> } >> } >> >> +static int prq_to_iommu_prot(struct page_req_dsc *req) >> +{ >> + int prot = 0; >> + >> + if (req->rd_req) >> + prot |= IOMMU_FAULT_PERM_READ; >> + if (req->wr_req) >> + prot |= IOMMU_FAULT_PERM_WRITE; >> + if (req->exe_req) >> + prot |= IOMMU_FAULT_PERM_EXEC; >> + if (req->pm_req) >> + prot |= IOMMU_FAULT_PERM_PRIV; >> + >> + return prot; >> +} >> + >> +static int >> +intel_svm_prq_report(struct device *dev, struct page_req_dsc *desc) >> +{ >> + struct iommu_fault_event event; >> + >> + /* Fill in event data for device specific processing */ >> + memset(&event, 0, sizeof(struct iommu_fault_event)); >> + event.fault.type = IOMMU_FAULT_PAGE_REQ; >> + event.fault.prm.addr = desc->addr; >> + event.fault.prm.pasid = desc->pasid; >> + event.fault.prm.grpid = desc->prg_index; >> + event.fault.prm.perm = prq_to_iommu_prot(desc); >> + >> + if (!dev || !dev_is_pci(dev)) >> + return -ENODEV; > > move the check before memset.
Yes.
> >> + >> + if (desc->lpig) >> + event.fault.prm.flags |= >> IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE; >> + if (desc->pasid_present) { >> + event.fault.prm.flags |= >> IOMMU_FAULT_PAGE_REQUEST_PASID_VALID; >> + event.fault.prm.flags |= >> IOMMU_FAULT_PAGE_RESPONSE_NEEDS_PASID; >> + } > > if pasid is not present, should we return error directly instead of > submitting the req and let iommu core to figure out? I don't have
This has been done in prq_event_thread(), so I don't need to check it again here.
> a strong preference, thus: > > Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Thanks a lot for your time.
Best regards, baolu
> >> + if (desc->priv_data_present) { >> + /* >> + * Set last page in group bit if private data is present, >> + * page response is required as it does for LPIG. >> + * iommu_report_device_fault() doesn't understand this >> vendor >> + * specific requirement thus we set last_page as a >> workaround. >> + */ >> + event.fault.prm.flags |= >> IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE; >> + event.fault.prm.flags |= >> IOMMU_FAULT_PAGE_REQUEST_PRIV_DATA; >> + memcpy(event.fault.prm.private_data, desc->priv_data, >> + sizeof(desc->priv_data)); >> + } >> + >> + return iommu_report_device_fault(dev, &event); >> +} >> + >> static irqreturn_t prq_event_thread(int irq, void *d) >> { >> + struct intel_svm_dev *sdev = NULL; >> struct intel_iommu *iommu = d; >> struct intel_svm *svm = NULL; >> int head, tail, handled = 0; >> @@ -828,7 +883,6 @@ static irqreturn_t prq_event_thread(int irq, void *d) >> tail = dmar_readq(iommu->reg + DMAR_PQT_REG) & >> PRQ_RING_MASK; >> head = dmar_readq(iommu->reg + DMAR_PQH_REG) & >> PRQ_RING_MASK; >> while (head != tail) { >> - struct intel_svm_dev *sdev; >> struct vm_area_struct *vma; >> struct page_req_dsc *req; >> struct qi_desc resp; >> @@ -864,6 +918,20 @@ static irqreturn_t prq_event_thread(int irq, void *d) >> } >> } >> >> + if (!sdev || sdev->sid != req->rid) { >> + struct intel_svm_dev *t; >> + >> + sdev = NULL; >> + rcu_read_lock(); >> + list_for_each_entry_rcu(t, &svm->devs, list) { >> + if (t->sid == req->rid) { >> + sdev = t; >> + break; >> + } >> + } >> + rcu_read_unlock(); >> + } >> + >> result = QI_RESP_INVALID; >> /* Since we're using init_mm.pgd directly, we should never >> take >> * any faults on kernel addresses. */ >> @@ -874,6 +942,17 @@ static irqreturn_t prq_event_thread(int irq, void *d) >> if (!is_canonical_address(address)) >> goto bad_req; >> >> + /* >> + * If prq is to be handled outside iommu driver via receiver of >> + * the fault notifiers, we skip the page response here. >> + */ >> + if (svm->flags & SVM_FLAG_GUEST_MODE) { >> + if (sdev && !intel_svm_prq_report(sdev->dev, req)) >> + goto prq_advance; >> + else >> + goto bad_req; >> + } >> + >> /* If the mm is already defunct, don't handle faults. */ >> if (!mmget_not_zero(svm->mm)) >> goto bad_req; >> @@ -892,24 +971,11 @@ static irqreturn_t prq_event_thread(int irq, void *d) >> goto invalid; >> >> result = QI_RESP_SUCCESS; >> - invalid: >> +invalid: >> mmap_read_unlock(svm->mm); >> mmput(svm->mm); >> - bad_req: >> - /* Accounting for major/minor faults? */ >> - rcu_read_lock(); >> - list_for_each_entry_rcu(sdev, &svm->devs, list) { >> - if (sdev->sid == req->rid) >> - break; >> - } >> - /* Other devices can go away, but the drivers are not >> permitted >> - * to unbind while any page faults might be in flight. So it's >> - * OK to drop the 'lock' here now we have it. */ >> - rcu_read_unlock(); >> - >> - if (WARN_ON(&sdev->list == &svm->devs)) >> - sdev = NULL; >> - >> +bad_req: >> + WARN_ON(!sdev); >> if (sdev && sdev->ops && sdev->ops->fault_cb) { >> int rwxp = (req->rd_req << 3) | (req->wr_req << 2) | >> (req->exe_req << 1) | (req->pm_req); >> @@ -920,7 +986,7 @@ static irqreturn_t prq_event_thread(int irq, void *d) >> and these can be NULL. Do not use them below this point! >> */ >> sdev = NULL; >> svm = NULL; >> - no_pasid: >> +no_pasid: >> if (req->lpig || req->priv_data_present) { >> /* >> * Per VT-d spec. v3.0 ch7.7, system software must >> @@ -945,6 +1011,7 @@ static irqreturn_t prq_event_thread(int irq, void *d) >> resp.qw3 = 0; >> qi_submit_sync(iommu, &resp, 1, 0); >> } >> +prq_advance: >> head = (head + sizeof(*req)) & PRQ_RING_MASK; >> } >> >> -- >> 2.17.1 >
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