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SubjectRE: [PATCH v4 17/22] iommu/intel-svm: report device page request
Date
Hi Jacob,

Same comment with the one to patch 16, pci_get_bus_and_slot() is
deprecated, may update accordingly.

Thanks,
Yi Liu

> From: Jacob Pan [mailto:jacob.jun.pan@linux.intel.com]
> Sent: Friday, March 23, 2018 11:12 AM
>
> If the source device of a page request has its PASID table pointer bound to a guest,
> the first level page tables are owned by the guest.
> In this case, we shall let guest OS to manage page fault.
>
> This patch uses the IOMMU fault reporting API to send fault events, possibly via VFIO,
> to the guest OS. Once guest pages are fault in, guest will issue page response which
> will be passed down via the invalidation passdown APIs.
>
> Recoverable faults, such as page request reporting is not limitted to guest use. In
> kernel driver can also request a chance to receive fault notifications.
>
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> Signed-off-by: Ashok Raj <ashok.raj@intel.com>
> ---
> drivers/iommu/intel-svm.c | 71 ++++++++++++++++++++++++++++++++++++++++---
> ----
> include/linux/iommu.h | 1 +
> 2 files changed, 62 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c index
> 99bc9bd..bdc702c 100644
> --- a/drivers/iommu/intel-svm.c
> +++ b/drivers/iommu/intel-svm.c
> @@ -580,6 +580,56 @@ static bool is_canonical_address(u64 addr)
> return (((saddr << shift) >> shift) == saddr); }
>
> +static int prq_to_iommu_prot(struct page_req_dsc *req) {
> + int prot = 0;
> +
> + if (req->rd_req)
> + prot |= IOMMU_FAULT_READ;
> + if (req->wr_req)
> + prot |= IOMMU_FAULT_WRITE;
> + if (req->exe_req)
> + prot |= IOMMU_FAULT_EXEC;
> + if (req->priv_req)
> + prot |= IOMMU_FAULT_PRIV;
> +
> + return prot;
> +}
> +
> +static int intel_svm_prq_report(struct page_req_dsc *desc) {
> + int ret = 0;
> + struct iommu_fault_event event;
> + struct pci_dev *pdev;
> +
> + memset(&event, 0, sizeof(struct iommu_fault_event));
> + pdev = pci_get_bus_and_slot(desc->bus, desc->devfn);
> + if (!pdev) {
> + pr_err("No PCI device found for PRQ [%02x:%02x.%d]\n",
> + desc->bus, PCI_SLOT(desc->devfn),
> + PCI_FUNC(desc->devfn));
> + return -ENODEV;
> + }
> +
> + /* Fill in event data for device specific processing */
> + event.type = IOMMU_FAULT_PAGE_REQ;
> + event.addr = (u64)desc->addr << VTD_PAGE_SHIFT;
> + event.pasid = desc->pasid;
> + event.page_req_group_id = desc->prg_index;
> + event.prot = prq_to_iommu_prot(desc);
> + event.last_req = desc->lpig;
> + event.pasid_valid = 1;
> + /* keep track of PRQ so that when the response comes back, we know
> + * whether we do group response or stream response. SRR[0] and
> + * private[54:32] bits in the descriptor are stored.
> + */
> + event.iommu_private = *(u64 *)desc;
> + 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;
> @@ -628,6 +678,16 @@ static irqreturn_t prq_event_thread(int irq, void *d)
> goto no_pasid;
> }
> }
> + /* If address is not canonical, return invalid response */
> + 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 (!intel_svm_prq_report(req))
> + goto prq_advance;
>
> result = QI_RESP_INVALID;
> /* Since we're using init_mm.pgd directly, we should never take @@
> -638,9 +698,6 @@ static irqreturn_t prq_event_thread(int irq, void *d)
> if (!mmget_not_zero(svm->mm))
> goto bad_req;
>
> - /* If address is not canonical, return invalid response */
> - if (!is_canonical_address(address))
> - goto bad_req;
>
> down_read(&svm->mm->mmap_sem);
> vma = find_extend_vma(svm->mm, address); @@ -673,12 +730,6
> @@ static irqreturn_t prq_event_thread(int irq, void *d)
>
> if (WARN_ON(&sdev->list == &svm->devs))
> sdev = NULL;
> -
> - if (sdev && sdev->ops && sdev->ops->fault_cb) {
> - int rwxp = (req->rd_req << 3) | (req->wr_req << 2) |
> - (req->exe_req << 1) | (req->priv_req);
> - sdev->ops->fault_cb(sdev->dev, req->pasid, req->addr, req-
> >private, rwxp, result);
> - }
> /* We get here in the error case where the PASID lookup failed,
> and these can be NULL. Do not use them below this point! */
> sdev = NULL;
> @@ -704,7 +755,7 @@ static irqreturn_t prq_event_thread(int irq, void *d)
>
> qi_submit_sync(&resp, iommu);
> }
> -
> + prq_advance:
> head = (head + sizeof(*req)) & PRQ_RING_MASK;
> }
>
> diff --git a/include/linux/iommu.h b/include/linux/iommu.h index 94cfda8..dbe2866
> 100644
> --- a/include/linux/iommu.h
> +++ b/include/linux/iommu.h
> @@ -42,6 +42,7 @@
> * if the IOMMU page table format is equivalent.
> */
> #define IOMMU_PRIV (1 << 5)
> +#define IOMMU_EXEC (1 << 6)
>
> struct iommu_ops;
> struct iommu_group;
> --
> 2.7.4

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