Re: [PATCH v7 08/11] iommu/vt-d: Misc macro clean up for SVM

Lu Baolu
2019-10-26T01:03:31Z

Hi,

On 10/25/19 3:55 AM, Jacob Pan wrote:
> Use combined macros for_each_svm_dev() to simplify SVM device iteration
> and error checking.
>
> Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
> Reviewed-by: Eric Auger <eric.auger@redhat.com>
> ---
> drivers/iommu/intel-svm.c | 89 ++++++++++++++++++++++-------------------------
> 1 file changed, 42 insertions(+), 47 deletions(-)
>
> diff --git a/drivers/iommu/intel-svm.c b/drivers/iommu/intel-svm.c
> index a9a7f85a09bc..a18b02a9709d 100644
> --- a/drivers/iommu/intel-svm.c
> +++ b/drivers/iommu/intel-svm.c
> @@ -212,6 +212,10 @@ static const struct mmu_notifier_ops intel_mmuops = {
> static DEFINE_MUTEX(pasid_mutex);
> static LIST_HEAD(global_svm_list);
>
> +#define for_each_svm_dev(svm, dev) \
> + list_for_each_entry(sdev, &svm->devs, list) \
> + if (dev == sdev->dev) \
> +
> int intel_svm_bind_mm(struct device *dev, int *pasid, int flags, struct svm_dev_ops *ops)
> {
> struct intel_iommu *iommu = intel_svm_device_to_iommu(dev);
> @@ -257,15 +261,13 @@ int intel_svm_bind_mm(struct device *dev, int *pasid, int flags, struct svm_dev_
> goto out;
> }
>
> - list_for_each_entry(sdev, &svm->devs, list) {
> - if (dev == sdev->dev) {
> - if (sdev->ops != ops) {
> - ret = -EBUSY;
> - goto out;
> - }
> - sdev->users++;
> - goto success;
> + for_each_svm_dev(svm, dev) {
> + if (sdev->ops != ops) {
> + ret = -EBUSY;
> + goto out;
> }
> + sdev->users++;
> + goto success;
> }
>
> break;
> @@ -402,50 +404,43 @@ int intel_svm_unbind_mm(struct device *dev, int pasid)
> goto out;
>
> svm = ioasid_find(NULL, pasid, NULL);
> - if (IS_ERR(svm)) {
> + if (IS_ERR_OR_NULL(svm)) {
> ret = PTR_ERR(svm);
> goto out;
> }
>
> - if (!svm)
> - goto out;

If svm == NULL here, this function will return success. This isn't
expected, right?

Others looks good to me.

Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>

Best regards,
baolu

> -
> - list_for_each_entry(sdev, &svm->devs, list) {
> - if (dev == sdev->dev) {
> - ret = 0;
> - sdev->users--;
> - if (!sdev->users) {
> - list_del_rcu(&sdev->list);
> - /* Flush the PASID cache and IOTLB for this device.
> - * Note that we do depend on the hardware *not* using
> - * the PASID any more. Just as we depend on other
> - * devices never using PASIDs that they have no right
> - * to use. We have a *shared* PASID table, because it's
> - * large and has to be physically contiguous. So it's
> - * hard to be as defensive as we might like. */
> - intel_pasid_tear_down_entry(iommu, dev, svm->pasid);
> - intel_flush_svm_range_dev(svm, sdev, 0, -1, 0);
> - kfree_rcu(sdev, rcu);
> -
> - if (list_empty(&svm->devs)) {
> - /* Clear private data so that free pass check */
> - ioasid_set_data(svm->pasid, NULL);
> - ioasid_free(svm->pasid);
> - if (svm->mm)
> - mmu_notifier_unregister(&svm->notifier, svm->mm);
> -
> - list_del(&svm->list);
> -
> - /* We mandate that no page faults may be outstanding
> - * for the PASID when intel_svm_unbind_mm() is called.
> - * If that is not obeyed, subtle errors will happen.
> - * Let's make them less subtle... */
> - memset(svm, 0x6b, sizeof(*svm));
> - kfree(svm);
> - }
> + for_each_svm_dev(svm, dev) {
> + ret = 0;
> + sdev->users--;
> + if (!sdev->users) {
> + list_del_rcu(&sdev->list);
> + /* Flush the PASID cache and IOTLB for this device.
> + * Note that we do depend on the hardware *not* using
> + * the PASID any more. Just as we depend on other
> + * devices never using PASIDs that they have no right
> + * to use. We have a *shared* PASID table, because it's
> + * large and has to be physically contiguous. So it's
> + * hard to be as defensive as we might like. */
> + intel_pasid_tear_down_entry(iommu, dev, svm->pasid);
> + intel_flush_svm_range_dev(svm, sdev, 0, -1, 0);
> + kfree_rcu(sdev, rcu);
> +
> + if (list_empty(&svm->devs)) {
> + /* Clear private data so that free pass check */
> + ioasid_set_data(svm->pasid, NULL);
> + ioasid_free(svm->pasid);
> + if (svm->mm)
> + mmu_notifier_unregister(&svm->notifier, svm->mm);
> + list_del(&svm->list);
> + /* We mandate that no page faults may be outstanding
> + * for the PASID when intel_svm_unbind_mm() is called.
> + * If that is not obeyed, subtle errors will happen.
> + * Let's make them less subtle... */
> + memset(svm, 0x6b, sizeof(*svm));
> + kfree(svm);
> }
> - break;
> }
> + break;
> }
> out:
> mutex_unlock(&pasid_mutex);
> @@ -581,7 +576,7 @@ static irqreturn_t prq_event_thread(int irq, void *d)
> * 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(svm) || !svm) {
> + 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]);