On Thu, Dec 19, 2019 at 05:30:33PM +0100, Jean-Philippe Brucker wrote:
> Enable PASID for PCI devices that support it. Since the SSID tables are
> allocated by arm_smmu_attach_dev(), PASID has to be enabled early enough.
> arm_smmu_dev_feature_enable() would be too late, since by that time the
What is arm_smmu_dev_feature_enable()?
> main DMA domain has already been attached. Do it in add_device() instead.
>
> Tested-by: Zhangfei Gao <zhangfei.gao@xxxxxxxxxx>
> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
> Signed-off-by: Jean-Philippe Brucker <jean-philippe@xxxxxxxxxx>
> ---
> drivers/iommu/arm-smmu-v3.c | 55 ++++++++++++++++++++++++++++++++++++-
> 1 file changed, 54 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iommu/arm-smmu-v3.c b/drivers/iommu/arm-smmu-v3.c
> index e62ca80f2f76..8e95ecad4c9a 100644
> --- a/drivers/iommu/arm-smmu-v3.c
> +++ b/drivers/iommu/arm-smmu-v3.c
> @@ -2644,6 +2644,53 @@ static void arm_smmu_disable_ats(struct arm_smmu_master *master)
> atomic_dec(&smmu_domain->nr_ats_masters);
> }
>
> +static int arm_smmu_enable_pasid(struct arm_smmu_master *master)
> +{
> + int ret;
> + int features;
> + int num_pasids;
> + struct pci_dev *pdev;
> +
> + if (!dev_is_pci(master->dev))
> + return -ENODEV;
> +
> + pdev = to_pci_dev(master->dev);
> +
> + features = pci_pasid_features(pdev);
> + if (features < 0)
> + return features;
> +
> + num_pasids = pci_max_pasids(pdev);
> + if (num_pasids <= 0)
> + return num_pasids;
> +
> + ret = pci_enable_pasid(pdev, features);
> + if (ret) {
> + dev_err(&pdev->dev, "Failed to enable PASID\n");
> + return ret;
> + }
> +
> + master->ssid_bits = min_t(u8, ilog2(num_pasids),
> + master->smmu->ssid_bits);
> + return 0;
> +}
> +
> +static void arm_smmu_disable_pasid(struct arm_smmu_master *master)
> +{
> + struct pci_dev *pdev;
> +
> + if (!dev_is_pci(master->dev))
> + return;
> +
> + pdev = to_pci_dev(master->dev);
> +
> + if (!pdev->pasid_enabled)
> + return;
> +
> + master->ssid_bits = 0;
> + pci_disable_pasid(pdev);
> +}
> +
> static void arm_smmu_detach_dev(struct arm_smmu_master *master)
> {
> unsigned long flags;
> @@ -2852,13 +2899,16 @@ static int arm_smmu_add_device(struct device *dev)
>
> master->ssid_bits = min(smmu->ssid_bits, fwspec->num_pasid_bits);
>
> + /* Note that PASID must be enabled before, and disabled after ATS */
> + arm_smmu_enable_pasid(master);
Is that part of the PCIe specs? If so, please can you add a citation to the
comment?
Are there any other ordering requirements, i.e. with respect to enabling
substreams at the SMMU? For example, can a speculative ATS request provide
a PASID?
Will
