Messages in this thread Patch in this message | | | Subject | Re: [PATCH 3/4] iommu/vt-d: Report page request faults for guest SVA | From | Lu Baolu <> | Date | Wed, 1 Jul 2020 10:27:22 +0800 |
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Hi Kevin,
Thanks a lot for reviewing my patches.
On 6/30/20 2:01 PM, Tian, Kevin wrote: >> From: Lu Baolu <baolu.lu@linux.intel.com> >> Sent: Sunday, June 28, 2020 8:34 AM >> >> 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 >> callback. >> >> 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 | 83 >> +++++++++++++++++++++++++++++++++++++-- >> 1 file changed, 80 insertions(+), 3 deletions(-) >> >> diff --git a/drivers/iommu/intel/svm.c b/drivers/iommu/intel/svm.c >> index c23167877b2b..4800bb6f8794 100644 >> --- a/drivers/iommu/intel/svm.c >> +++ b/drivers/iommu/intel/svm.c >> @@ -815,6 +815,69 @@ 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 intel_iommu *iommu, struct page_req_dsc >> *desc) >> +{ >> + struct iommu_fault_event event; >> + struct pci_dev *pdev; >> + u8 bus, devfn; >> + int ret = 0; >> + >> + memset(&event, 0, sizeof(struct iommu_fault_event)); >> + bus = PCI_BUS_NUM(desc->rid); >> + devfn = desc->rid & 0xff; >> + pdev = pci_get_domain_bus_and_slot(iommu->segment, bus, devfn); > > Is this step necessary? dev can be passed in (based on sdev), and more > importantly iommu_report_device_fault already handles the ref counting > e.g. get_device(dev) when fault handler is valid...
Yes, agreed. I will pass device in instead.
> >> + >> + if (!pdev) { >> + pr_err("No PCI device found for PRQ [%02x:%02x.%d]\n", >> + bus, PCI_SLOT(devfn), PCI_FUNC(devfn)); >> + return -ENODEV; >> + } >> + >> + /* Fill in event data for device specific processing */ >> + 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); >> + >> + /* >> + * Set last page in group bit if private data is present, >> + * page response is required as it does for LPIG. >> + */ >> + 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; >> + if (desc->priv_data_present) { >> + event.fault.prm.flags |= >> IOMMU_FAULT_PAGE_REQUEST_LAST_PAGE; > > why setting lpig under this condition?
/* * Per VT-d spec. v3.0 ch7.7, system software must * respond with page group response if private data * is present (PDP) or last page in group (LPIG) bit * is set. This is an additional VT-d feature beyond * PCI ATS spec. */
> >> + event.fault.prm.flags |= >> IOMMU_FAULT_PAGE_REQUEST_PRIV_DATA; >> + memcpy(event.fault.prm.private_data, desc->priv_data, >> + sizeof(desc->priv_data)); >> + } >> + >> + ret = iommu_report_device_fault(&pdev->dev, &event); >> + pci_dev_put(pdev); >> + >> + return ret; >> +} >> + >> static irqreturn_t prq_event_thread(int irq, void *d) >> { >> struct intel_iommu *iommu = d; >> @@ -874,6 +937,19 @@ 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) { >> + int res = intel_svm_prq_report(iommu, req); >> + >> + if (!res) >> + goto prq_advance; >> + else >> + goto bad_req; >> + } >> + > > I noted in bad_req there is another reporting logic: > > 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); > sdev->ops->fault_cb(sdev->dev, req->pasid, req->addr, > req->priv_data, rwxp, result); > } > > It was introduced in the 1st version of svm.c. It might be unrelated to > this patch, but I wonder whether that one should be replaced with > iommu_report_device_fault too?
This call back will be deprecated. The previous api in generic iommu has been removed.
https://www.spinics.net/lists/iommu/msg43657.html
I will make it in a separated patch.
> > Thanks > Kevin
Best regards, baolu
>> /* If the mm is already defunct, don't handle faults. */ >> if (!mmget_not_zero(svm->mm)) >> goto bad_req; >> @@ -892,10 +968,10 @@ 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: >> +bad_req: >> /* Accounting for major/minor faults? */ >> rcu_read_lock(); >> list_for_each_entry_rcu(sdev, &svm->devs, list) { >> @@ -920,7 +996,7 @@ 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 +1021,7 @@ 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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