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    SubjectRE: [PATCH v2 4/7] iommu/vt-d: Refactor prq_event_thread()
    Date
    > From: Lu Baolu <baolu.lu@linux.intel.com>
    > Sent: Wednesday, April 15, 2020 1:26 PM
    >
    > Move the software processing page request descriptors part from
    > prq_event_thread() into a separated function. No any functional
    > changes.
    >
    > Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>
    > ---
    > drivers/iommu/intel-svm.c | 256 ++++++++++++++++++++------------------
    > 1 file changed, 135 insertions(+), 121 deletions(-)
    >
    > diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c
    > index 83dc4319f661..a1921b462783 100644
    > --- a/drivers/iommu/intel-svm.c
    > +++ b/drivers/iommu/intel-svm.c
    > @@ -722,142 +722,156 @@ static bool is_canonical_address(u64 addr)
    > return (((saddr << shift) >> shift) == saddr);
    > }
    >
    > -static irqreturn_t prq_event_thread(int irq, void *d)
    > +static void process_single_prq(struct intel_iommu *iommu,
    > + struct page_req_dsc *req)
    > {
    > - struct intel_iommu *iommu = d;
    > - struct intel_svm *svm = NULL;
    > - int head, tail, handled = 0;
    > -
    > - /* Clear PPR bit before reading head/tail registers, to
    > - * ensure that we get a new interrupt if needed. */
    > - writel(DMA_PRS_PPR, iommu->reg + DMAR_PRS_REG);
    > -
    > - 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;
    > - int result;
    > - vm_fault_t ret;
    > - u64 address;
    > -
    > - handled = 1;
    > -
    > - req = &iommu->prq[head / sizeof(*req)];
    > + int result = QI_RESP_FAILURE;
    > + struct intel_svm_dev *sdev;
    > + struct vm_area_struct *vma;
    > + struct intel_svm *svm;
    > + struct qi_desc resp;
    > + vm_fault_t ret;
    > + u64 address;
    > +
    > + address = (u64)req->addr << VTD_PAGE_SHIFT;
    > + if (!req->pasid_present) {
    > + pr_err("%s: Page request without PASID: %08llx %08llx\n",
    > + iommu->name, ((unsigned long long *)req)[0],
    > + ((unsigned long long *)req)[1]);
    > + goto no_pasid;
    > + }
    >
    > - result = QI_RESP_FAILURE;
    > - address = (u64)req->addr << VTD_PAGE_SHIFT;
    > - if (!req->pasid_present) {
    > - pr_err("%s: Page request without
    > PASID: %08llx %08llx\n",
    > - iommu->name, ((unsigned long long *)req)[0],
    > - ((unsigned long long *)req)[1]);
    > - goto no_pasid;
    > - }
    > + rcu_read_lock();
    > + svm = ioasid_find(NULL, req->pasid, NULL);
    > + /*
    > + * It *can't* go away, because the driver is not permitted
    > + * to unbind the mm while any page faults are outstanding.
    > + * So we only need RCU to protect the internal idr code.
    > + */
    > + rcu_read_unlock();
    >
    > - if (!svm || svm->pasid != req->pasid) {
    > - rcu_read_lock();
    > - svm = ioasid_find(NULL, req->pasid, NULL);
    > - /* It *can't* go away, because the driver is not
    > permitted
    > - * to unbind the mm while any page faults are
    > outstanding.
    > - * So we only need RCU to protect the internal idr
    > code. */
    > - rcu_read_unlock();
    > - if (IS_ERR_OR_NULL(svm)) {
    > - pr_err("%s: Page request for invalid
    > PASID %d: %08llx %08llx\n",
    > - iommu->name, req->pasid, ((unsigned
    > long long *)req)[0],
    > - ((unsigned long long *)req)[1]);
    > - goto no_pasid;
    > - }
    > - }
    > + if (IS_ERR_OR_NULL(svm)) {
    > + pr_err("%s: Page request for invalid
    > PASID %d: %08llx %08llx\n",
    > + iommu->name, req->pasid, ((unsigned long long *)req)[0],
    > + ((unsigned long long *)req)[1]);
    > + goto no_pasid;
    > + }
    >
    > - result = QI_RESP_INVALID;
    > - /* Since we're using init_mm.pgd directly, we should never
    > take
    > - * any faults on kernel addresses. */
    > - if (!svm->mm)
    > - goto bad_req;
    > + result = QI_RESP_INVALID;
    > + /* Since we're using init_mm.pgd directly, we should never take
    > + * any faults on kernel addresses. */
    > + if (!svm->mm)
    > + goto bad_req;
    > +
    > + /* If address is not canonical, return invalid response */
    > + if (!is_canonical_address(address))
    > + goto bad_req;
    > +
    > + /* If the mm is already defunct, don't handle faults. */
    > + if (!mmget_not_zero(svm->mm))
    > + goto bad_req;
    > +
    > + down_read(&svm->mm->mmap_sem);
    > + vma = find_extend_vma(svm->mm, address);
    > + if (!vma || address < vma->vm_start)
    > + goto invalid;
    > +
    > + if (access_error(vma, req))
    > + goto invalid;
    > +
    > + ret = handle_mm_fault(vma, address,
    > + req->wr_req ? FAULT_FLAG_WRITE : 0);
    > + if (ret & VM_FAULT_ERROR)
    > + goto invalid;
    > +
    > + result = QI_RESP_SUCCESS;
    > +invalid:
    > + up_read(&svm->mm->mmap_sem);
    > + 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;
    > + }
    >
    > - /* If address is not canonical, return invalid response */
    > - if (!is_canonical_address(address))
    > - goto bad_req;
    > + /* 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 the mm is already defunct, don't handle faults. */
    > - if (!mmget_not_zero(svm->mm))
    > - goto bad_req;
    > + if (WARN_ON(&sdev->list == &svm->devs))
    > + sdev = NULL;
    >
    > - down_read(&svm->mm->mmap_sem);
    > - vma = find_extend_vma(svm->mm, address);
    > - if (!vma || address < vma->vm_start)
    > - goto invalid;
    > + 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);
    > + }
    >
    > - if (access_error(vma, req))
    > - goto invalid;
    > + /* 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;
    > + svm = NULL;
    > +no_pasid:
    > + if (req->lpig || req->priv_data_present) {
    > + /*
    > + * 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.
    > + */
    > + resp.qw0 = QI_PGRP_PASID(req->pasid) |
    > + QI_PGRP_DID(req->rid) |
    > + QI_PGRP_PASID_P(req->pasid_present) |
    > + QI_PGRP_PDP(req->pasid_present) |
    > + QI_PGRP_RESP_CODE(result) |
    > + QI_PGRP_RESP_TYPE;
    > + resp.qw1 = QI_PGRP_IDX(req->prg_index) |
    > + QI_PGRP_LPIG(req->lpig);
    > +
    > + if (req->priv_data_present)
    > + memcpy(&resp.qw2, req->priv_data,
    > + sizeof(req->priv_data));
    > + resp.qw2 = 0;
    > + resp.qw3 = 0;
    > + qi_submit_sync(iommu, &resp, 1, 0);
    > + }
    > +}
    >
    > - ret = handle_mm_fault(vma, address,
    > - req->wr_req ? FAULT_FLAG_WRITE : 0);
    > - if (ret & VM_FAULT_ERROR)
    > - goto invalid;
    > +static void intel_svm_process_prq(struct intel_iommu *iommu,
    > + struct page_req_dsc *prq,
    > + int head, int tail)
    > +{
    > + struct page_req_dsc *req;
    >
    > - result = QI_RESP_SUCCESS;
    > - invalid:
    > - up_read(&svm->mm->mmap_sem);
    > - 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;
    > -
    > - 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);
    > - }
    > - /* 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;
    > - svm = NULL;
    > - no_pasid:
    > - if (req->lpig || req->priv_data_present) {
    > - /*
    > - * 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.
    > - */
    > - resp.qw0 = QI_PGRP_PASID(req->pasid) |
    > - QI_PGRP_DID(req->rid) |
    > - QI_PGRP_PASID_P(req->pasid_present) |
    > - QI_PGRP_PDP(req->pasid_present) |
    > - QI_PGRP_RESP_CODE(result) |
    > - QI_PGRP_RESP_TYPE;
    > - resp.qw1 = QI_PGRP_IDX(req->prg_index) |
    > - QI_PGRP_LPIG(req->lpig);
    > -
    > - if (req->priv_data_present)
    > - memcpy(&resp.qw2, req->priv_data,
    > - sizeof(req->priv_data));
    > - resp.qw2 = 0;
    > - resp.qw3 = 0;
    > - qi_submit_sync(iommu, &resp, 1, 0);
    > - }
    > + while (head != tail) {
    > + req = &iommu->prq[head / sizeof(*req)];
    > + process_single_prq(iommu, req);
    > head = (head + sizeof(*req)) & PRQ_RING_MASK;
    > }
    > +}
    > +
    > +static irqreturn_t prq_event_thread(int irq, void *d)
    > +{
    > + struct intel_iommu *iommu = d;
    > + int head, tail;
    >
    > + /*
    > + * Clear PPR bit before reading head/tail registers, to
    > + * ensure that we get a new interrupt if needed.
    > + */
    > + writel(DMA_PRS_PPR, iommu->reg + DMAR_PRS_REG);
    > +
    > + tail = dmar_readq(iommu->reg + DMAR_PQT_REG) &
    > PRQ_RING_MASK;
    > + head = dmar_readq(iommu->reg + DMAR_PQH_REG) &
    > PRQ_RING_MASK;
    > + intel_svm_process_prq(iommu, iommu->prq, head, tail);
    > dmar_writeq(iommu->reg + DMAR_PQH_REG, tail);
    >
    > - return IRQ_RETVAL(handled);
    > + return IRQ_RETVAL(1);

    this might be a functional change, since previously (0) could
    be returned when head==tail.

    > }
    >
    > #define to_intel_svm_dev(handle) container_of(handle, struct
    > intel_svm_dev, sva)
    > --
    > 2.17.1

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