Re: [PATCH 1/2] dmaengine: idxd: Add enable/disable device IOPF feature

Dave Jiang
2023-02-03T16:08:30Z

On 2/3/23 1:44 AM, Lu Baolu wrote:
> The iommu subsystem requires IOMMU_DEV_FEAT_IOPF must be enabled before
> and disabled after IOMMU_DEV_FEAT_SVA, if device's I/O page faults rely
> on the IOMMU. Add explicit IOMMU_DEV_FEAT_IOPF enabling/disabling in this
> driver.
>
> At present, missing IOPF enabling/disabling doesn't cause any real issue,
> because the IOMMU driver places the IOPF enabling/disabling in the path
> of SVA feature handling. But this may change.
>
> Signed-off-by: Lu Baolu <baolu.lu@linux.intel.com>

Reviewed-by: Dave Jiang <dave.jiang@intel.com>

> ---
> drivers/dma/idxd/init.c | 31 +++++++++++++++++++++++++------
> 1 file changed, 25 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/dma/idxd/init.c b/drivers/dma/idxd/init.c
> index 529ea09c9094..d5a709a842a8 100644
> --- a/drivers/dma/idxd/init.c
> +++ b/drivers/dma/idxd/init.c
> @@ -511,6 +511,27 @@ static void idxd_disable_system_pasid(struct idxd_device *idxd)
> idxd->sva = NULL;
> }
>
> +static int idxd_enable_sva(struct pci_dev *pdev)
> +{
> + int ret;
> +
> + ret = iommu_dev_enable_feature(&pdev->dev, IOMMU_DEV_FEAT_IOPF);
> + if (ret)
> + return ret;
> +
> + ret = iommu_dev_enable_feature(&pdev->dev, IOMMU_DEV_FEAT_SVA);
> + if (ret)
> + iommu_dev_disable_feature(&pdev->dev, IOMMU_DEV_FEAT_IOPF);
> +
> + return ret;
> +}
> +
> +static void idxd_disable_sva(struct pci_dev *pdev)
> +{
> + iommu_dev_disable_feature(&pdev->dev, IOMMU_DEV_FEAT_SVA);
> + iommu_dev_disable_feature(&pdev->dev, IOMMU_DEV_FEAT_IOPF);
> +}
> +
> static int idxd_probe(struct idxd_device *idxd)
> {
> struct pci_dev *pdev = idxd->pdev;
> @@ -525,7 +546,7 @@ static int idxd_probe(struct idxd_device *idxd)
> dev_dbg(dev, "IDXD reset complete\n");
>
> if (IS_ENABLED(CONFIG_INTEL_IDXD_SVM) && sva) {
> - if (iommu_dev_enable_feature(dev, IOMMU_DEV_FEAT_SVA)) {
> + if (idxd_enable_sva(pdev)) {
> dev_warn(dev, "Unable to turn on user SVA feature.\n");
> } else {
> set_bit(IDXD_FLAG_USER_PASID_ENABLED, &idxd->flags);
> @@ -573,21 +594,19 @@ static int idxd_probe(struct idxd_device *idxd)
> if (device_pasid_enabled(idxd))
> idxd_disable_system_pasid(idxd);
> if (device_user_pasid_enabled(idxd))
> - iommu_dev_disable_feature(dev, IOMMU_DEV_FEAT_SVA);
> + idxd_disable_sva(pdev);
> return rc;
> }
>
> static void idxd_cleanup(struct idxd_device *idxd)
> {
> - struct device *dev = &idxd->pdev->dev;
> -
> perfmon_pmu_remove(idxd);
> idxd_cleanup_interrupts(idxd);
> idxd_cleanup_internals(idxd);
> if (device_pasid_enabled(idxd))
> idxd_disable_system_pasid(idxd);
> if (device_user_pasid_enabled(idxd))
> - iommu_dev_disable_feature(dev, IOMMU_DEV_FEAT_SVA);
> + idxd_disable_sva(idxd->pdev);
> }
>
> static int idxd_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
> @@ -705,7 +724,7 @@ static void idxd_remove(struct pci_dev *pdev)
> pci_free_irq_vectors(pdev);
> pci_iounmap(pdev, idxd->reg_base);
> if (device_user_pasid_enabled(idxd))
> - iommu_dev_disable_feature(&pdev->dev, IOMMU_DEV_FEAT_SVA);
> + idxd_disable_sva(pdev);
> pci_disable_device(pdev);
> destroy_workqueue(idxd->wq);
> perfmon_pmu_remove(idxd);